Bosch CIS fuel pressure gauge

[Trstno1]

Ok guys-

I just received my Bosch k-jet CIS gauge in the mail. I have it hooked up. I have read the directions but am not sure what I should be reading. What is:

Cold pressure control: engine cold, valve open - what should it read?
Warm control pressure: engine warm, valve open - what should it read?
Primary pressure: venting cold or warm, valve closed: what should it read?
Rest pressure: engine off - what should it read?

What is the proper procedure for testing? Should I run these tests with the car running or just jumper the RPM relay?

[DMCMW Dave]

Ok guys-

What is the proper procedure for testing? Should I run these tests with the car running or just jumper the RPM relay?

Didn't it come with an instruction sheet? Also see the service manual D:02:01 and :2. Includes charts and connection drawings.

Car needs to be running. Except for the rest pressure test. When cold should start low and gradually rise to the operating spec, and during that rise time it should drop quickly if you spike the throttle, then become very solid. at about 3.5 Bar (see manual for exact pressures).

[Trstno1]

Didn't it come with an instruction sheet? Also see the service manual D:02:01 and :2. Includes charts and connection drawings.

Car needs to be running. Except for the rest pressure test. When cold should start low and gradually rise to the operating spec, and during that rise time it should drop quickly if you spike the throttle, then become very solid. at about 3.5 Bar (see manual for exact pressures).

Thanks as always for the reply Dave!


I did get an instruction manual, I'm just trying to wrap my head around the tests and what they mean if the tested pressure values are different from that of the delorean technical manual specifications.


So to test primary pressure I close the valve, jumper the RPM relay right? The technical manual says the pressure should be 4.9 bar - 5.5 bar. This test is to show fuel pressure from fuel distributer right?

To test control pressure I open the valve, and start the engine. It should start at about 1.5 bar and stabilize at 3.5 bars or 50 psi once engine is warm right? If I blip the throttle the pressure should drop but then stabilize back up to 3.5 bar yes? This test reveals that the pressure regulator in the fuel distributer is working correctly?

To test rest pressure I basically act like I'm testing control pressure but just shut the motor off after the control pressure has stabilized and time the pressure leakage right? The technical manual says the rest pressure should be 3.3 bars with a minimum pressure after 10 minutes of 1.7 bars. Any more loss of pressure than that proves what exactly? Either I have injectors leaking fuel after shut down or a cold start valve leaking fuel after shut down. Any thing else it could be? Bad PPR O rings? Bad check valve off of the fuel pump? Hmmm...

Which of these tests will tell me if the WUR is functioning correctly?

I will run all these tests in the am and report back my findings.

[Trstno1]

Ok so I competed some tests this morning. Please tell me what you think.

Primary pressure is 5 bar

Control pressure starts at 40 psi and slowly stabilizes up to 50 psi or 3.5 bar - the blip of the throttle when cold takes the pressure down to 40 psi and it slowly increases to 50 psi again. Once the car is warm blipping the throttle does nothing to the control pressure, it stays steady at 50 psi. Am I correct in saying the WUR appears to be working, but slowly....is that normal?

Rest pressure appears good. Its over 3 bar on shut down and only goes down to 2.6 bar after 20 minutes. -though at some point it drops to zero - not sure if this is normal or not. ( I have checked my fuel injectors and cold start valve for leaking after shutdown and they all appear to be good with no leak). Why does the pressure eventually go to 0? Shouldn't the car hold rest pressure if no leaks are present?

Dwell reads 44 upon warm up. full throttle switch makes it go 50. once car warms up it tends to hunt a bit, anywhere from 30-45 but only sometimes. other times it stays steady at 44. Would a reading of 44 indicate a little too much fuel or not enough? either way my exhaust stinks.....

Please check out my video and tell me what you guys think: https://www.youtube.com/watch?v=pUvvGSj1Ikk

I am trouble shooting a cold start issue with hunting upon start and generally a lumpy idle. My fuel pressures seem to be within spec so what is the next step? testing injectors? vacuum? ignition? Ill change the spark plugs today and see if it makes any difference. Ill also pull the injectors and do a spray pattern test.

[Bitsyncmaster]

Your control pressure should start at a lower pressure. 20 PSI is what I've seen on a cold engine but it starts moving up pretty quickly.

Something is wrong if your dwell is holding steady at 44 deg. on a warm engine. The warm engine should always be adjusting the dwell. Have you replaced the O2 sensor yet?

My rest pressure will hold for about 3 hours with my RPM relay fix disabled.

[Ron]

I'm just trying to wrap my head around the tests...

So to test primary pressure I close the valve, jumper the RPM relay right? The technical manual says the pressure should be 4.9 bar - 5.5 bar. This test is to show fuel pressure from fuel distributer right?Yes.
This test confirms the Pump is creating enough primary pressure, the Primary Pressure Regulator (PPR) is working correctly, and that fuel is passing through that section of the FD on its way to the Control Pressure Regulator (AKA CPR, or Warm Up Regulator (WUR) ).


To test control pressure I open the valve, and start the engine. It should start at about 1.5 bar and stabilize at 3.5 bars or 50 psi once engine is warm right?
Yes (...1.5 bar, IF you started the test after the engine has sat all night and was around was around 50° F. when you started).
***


If I blip the throttle the pressure should drop but then stabilize back up to 3.5 bar yes?Yes.


This test reveals that the pressure regulator in the fuel distributer is working correctly?
No, the pressure regulator inside the Fuel Distributor (FD) is the Primary Pressure Regulator (PPR) mentioned above.

This test reveals that the pressure from the FD, mentioned above, should reach the Control Pressure Regulator (CPR...) and that it is regulating control pressure correctly. (It is mounted on the left valve cover.)


To test rest pressure I basically act like I'm testing control pressure but just shut the motor off after the control pressure has stabilized and time the pressure leakage right?
Yep, that will work.


The technical manual says the rest pressure should be 3.3 bars with a minimum pressure after 10 minutes of 1.7 bars. Any more loss of pressure than that proves what exactly? Either I have injectors leaking fuel after shut down or a cold start valve leaking fuel after shut down. Any thing else it could be? Bad PPR O rings? Bad check valve off of the fuel pump? Hmmm...
This test shows if you have ANY pressure leaks. (This includes all of the places you mentioned...and more ;-)


Which of these tests will tell me if the WUR is functioning correctly?
***
The Control Pressure test (valve open) -- Remember, the Control Pressure Regulator and Warm Up Regulator is the same part!

[Trstno1]

Your control pressure should start at a lower pressure. 20 PSI is what I've seen on a cold engine but it starts moving up pretty quickly.

Something is wrong if your dwell is holding steady at 44 deg. on a warm engine. The warm engine should always be adjusting the dwell. Have you replaced the O2 sensor yet?

My rest pressure will hold for about 3 hours with my RPM relay fix disabled.

The control pressure shown in the video was a cold start. It seems as though the warm engine is adjusting dwell constantly. The O2 sensor was replaced last summer, but then again I drove the summer with the new O2 sensor with a iSM seized 3/4 closed. Maybe that's what bad. I am letting it idle now to come up to temp and see if it starts hunting.

What would it mean if the control pressure starts so high? It seems after a cold start its immediately at 40 psi and gradually increases to a little over 50 psi before it stabilizes.

I'll let it warm up and shoot another video of the behavior.

[Trstno1]

Ok -

I was attempting a fuel injector flow test to see the spray patterns. I also swapped the spark plugs since they have not been swapped since the engine work. Here is the video: https://www.youtube.com/watch?v=fAMB7BDaUv8

Also....

here is a video of the dwell hunt after the car was warmed up. Too rich, to lean? https://www.youtube.com/watch?v=7PUEhEiOOrA

Would you let me know if you guys are getting volume with the video? They seem to play fine on my Ipad but I have not volume on the PC I just upgraded to Windows 7. Thanks!

[Ron]

RE the vid:
IFF your plugs, timing, idle RPM, etc are correct, there are no vacuum leaks, and it is fully warm, you need to lower the dwell to swing equally above and below 40°. This will take a very, very, very, little turn.

If the control pressure doesn't recover (to ~50) after fully warm (fans have cycles a few times) and revving, you might test the delay valve (see manual).

[Ron]

After seeing latest vid: Dwell looks good now. I would double check all settings, put some new plugs (save those tho) and injector cleaner in it, then run dwell check again after running a tank full through it.

...the initial seeking right after a start could easily be from the leaky injector(s)...ie the extra fuel has to be burn off and not fool the O2 sensor, so to speak. Uneven injector delivery can screw that up at other times too.

40 psi is correct if the engine sat all night at ~80° F. Once you start it. even for a few seconds, all bets are off!
Look at it as a choke, it only matters until the engine is warm (above 104F, or 40C, and @ 50 psi, basically forget it.

[DMCMW Dave]

The control pressure shown in the video was a cold start.

What would it mean if the control pressure starts so high? It seems after a cold start its immediately at 40 psi and gradually increases to a little over 50 psi before it stabilizes.
.

How cold? If "overnight Alaska" cold, that is way to high to start with. Dave M is right - should start at more like 20 psi. If overnight in a 80F degree heated garage, it's probably OK. That can really only be a bad regulator, only way to tell for sure is swap it. Too bad, because it appears to have the right pressure as soon as it warms up. Strange failure mode. More typical of a bad regulator is a 70psi reading all the time.

[MikeWard]

Ok so I competed some tests this morning. Please tell me what you think.

Primary pressure is 5 bar
I would add some a shim or two to it, to put it back to the book values - would aim for 5.2 to 5.3 bar.

Adjustment shims are available from the Eurotec club for this purpose if required, as mentioned in this topic here: http://dmctalk.org/showthread.php?12373-Fuel-Pressure-Regulator-Shims



Control pressure starts at 40 psi and slowly stabilizes up to 50 psi or 3.5 bar - the blip of the throttle when cold takes the pressure down to 40 psi and it slowly increases to 50 psi again. Once the car is warm blipping the throttle does nothing to the control pressure, it stays steady at 50 psi. Am I correct in saying the WUR appears to be working, but slowly....is that normal?Per your video, at the rate the control pressure rose up to 3.5 bar, I assume you had the electrical plug connected to it?

For testing the control pressure from cold, the CPR (or WUR as it is sometimes referred to) should be tested with the electrical plug disconnected and the vacuum pipes removed.

Use a thermometer to measure the temperature of the CPR casing, and reference this to the temp/pressure chart in the manual as the engine warms up:
40400

[Trstno1]

How cold? If "overnight Alaska" cold, that is way to high to start with. Dave M is right - should start at more like 20 psi. If overnight in a 80F degree heated garage, it's probably OK. That can really only be a bad regulator, only way to tell for sure is swap it. Too bad, because it appears to have the right pressure as soon as it warms up. Strange failure mode. More typical of a bad regulator is a 70psi reading all the time.

I have the heat up in the garage since I've been working on the car. I think it's set at 65 degrees.

And did you mean it would be a bad warm up regulator or primary pressure regulator? Also, what do you think the consequences of such a high cold start control pressure would be? Does it really hurt anything?

[Ron]

Just in case, it seems you are missing the idea behind the WUR/CPR... if the WUR (and thus engine) is cold, it will lower the control pressure to enrich the fuel and then lean it out to normal operating pressure (50 psi)/fuel ratio as the engine warms up.
If it has been in a heated area, it would start control pressure at a higher rate than 20 psi ie expected/'normal'.

FWIW:
-Mine at 55° F, will start off at ~24 psi and go to the 50 psi quickly ( < minute or so, iirc).
-I would expect it to start at the 40 psi, if it were ~85° F and go to 50 psi within a few seconds.
-Having sat in a heated area at the 65 ° F overnight, I'd expect it to start at ~26° F....that be the case, yours is a little off but it's not that critical, as long as it hits and holds 50 psi when fully warm.
-Again, the engine must not run for hours, preferably sat over night (internal cylinder temp is what matters most, not ambient air), you have one very short time period to check it...

FWIW- I would not mess with the Primary Pressure with it being at 5.0 bar because it is within the "checking value" specs given in the manual at D:02:01 of 4.9-5.5 Bar (71-79psi)....(don't see 0.1 psi off of "setting value" as the problem)

P.S. Dave was saying the CPR;WUR could be bad, not PPR.

P.P.S. IMHO, once you run it around a little with some cleaner in it and fresh plugs, I'd bet the only problem you have (expect possibly a bad WUR, which I would not bet on yet) would be to only see a hunting problem during warm up, which is typical IF your injectors are not flowing exactly the same AT IDLE and/or ALL settings etc correct before adjusting the CO (Dwell) LAST. They are just particularly fussy when cold.

Hope this helps.....

[DMCMW Dave]

I have the heat up in the garage since I've been working on the car. I think it's set at 65 degrees.

And did you mean it would be a bad warm up regulator or primary pressure regulator? Also, what do you think the consequences of such a high cold start control pressure would be? Does it really hurt anything?

Warmup regulator. And if you can live with awful performance until warm-up, it's not hurting anything given the pressures you are seeing. It's just way too lean for a few minutes and will be hard to get moving, i.e. will tend to stall when you let out the clutch (or put in drive). It will be a lot worse if you happen to park the car out in the real cold, maybe even hard to start (seems like you may be seeing that problem, although it would be more of a start/die/stare/die a few times and then it would run.

For future reference, if the pressure were to stabilize too high, you would need to fix it for sure.

[Trstno1]

Yes! thank you very much!



Just in case, it seems you are missing the idea behind the WUR/CPR... if the WUR (and thus engine) is cold, it will lower the control pressure to enrich the fuel and then lean it out to normal operating pressure (50 psi)/fuel ratio as the engine warms up.
If it has been in a heated area, it would start control pressure at a higher rate than 20 psi ie expected/'normal'.

FWIW:
-Mine at 55° F, will start off at ~24 psi and go to the 50 psi quickly ( < minute or so, iirc).
-I would expect it to start at the 40 psi, if it were ~85° F and go to 50 psi within a few seconds.
-Having sat in a heated area at the 65 ° F overnight, I'd expect it to start at ~26° F....that be the case, yours is a little off but it's not that critical, as long as it hits and holds 50 psi when fully warm.
-Again, the engine must not run for hours, preferably sat over night (internal cylinder temp is what matters most, not ambient air), you have one very short time period to check it...

FWIW- I would not mess with the Primary Pressure with it being at 5.0 bar because it is within the "checking value" specs given in the manual at D:02:01 of 4.9-5.5 Bar (71-79psi)....(don't see 0.1 psi off of "setting value" as the problem)

P.S. Dave was saying the CPR;WUR could be bad, not PPR.

P.P.S. IMHO, once you run it around a little with some cleaner in it and fresh plugs, I'd bet the only problem you have (expect possibly a bad WUR, which I would not bet on yet) would be to only see a hunting problem during warm up, which is typical IF your injectors are not flowing exactly the same AT IDLE and/or ALL settings etc correct before adjusting the CO (Dwell) LAST. They are just particularly fussy when cold.

Hope this helps.....

[Trstno1]

I really appreciate the information. I will order a new WUR tomorrow and recheck the control pressure after the install. Would this also potentially be the reason I crank so much prior to the car cold starting? Thanks very much for all the help!




Warmup regulator. And if you can live with awful performance until warm-up, it's not hurting anything given the pressures you are seeing. It's just way too lean for a few minutes and will be hard to get moving, i.e. will tend to stall when you let out the clutch (or put in drive). It will be a lot worse if you happen to park the car out in the real cold, maybe even hard to start (seems like you may be seeing that problem, although it would be more of a start/die/stare/die a few times and then it would run.

For future reference, if the pressure were to stabilize too high, you would need to fix it for sure.

[DMCMW Dave]

I really appreciate the information. I will order a new WUR tomorrow and recheck the control pressure after the install. Would this also potentially be the reason I crank so much prior to the car cold starting? Thanks very much for all the help!

Probably not. You need to check the cold start valve to see if it sprays when engine is cold. They rarely fail but the thermo-time switch, or bad wiring, will cause that.

If the valve isn't spraying, do the "plug swap" or "hot wire inside" to force it, and see if it works.

Plug Swap - connect the gray warmup regulator plug to the blue injector. This will fire the injector as long as the engine is running, so you need to disconnect it ASAP when it starts or it will flood. This also tends to wear out the connectors.

"hot wire inside" - Locate the unused relay socket at the back of the electrical compartment. Usually white but sometimes black. Jumper the white-red to the blue-black. This will fire the injector as long as the engine is cranking. Will be great when cold, will flood it when hot so don't just leave the jumper in place. DO NOT CONNECT ANYTHING TO THE BLACK (ground) wire or you will melt things. Some folks wire this as a push-button to avoid replacing the thermotime switch.

[Trstno1]

Probably not. You need to check the cold start valve to see if it sprays when engine is cold. They rarely fail but the thermo-time switch, or bad wiring, will cause that.

If the valve isn't spraying, do the "plug swap" or "hot wire inside" to force it, and see if it works.

Plug Swap - connect the gray warmup regulator plug to the blue injector. This will fire the injector as long as the engine is running, so you need to disconnect it ASAP when it starts or it will flood. This also tends to wear out the connectors.

"hot wire inside" - Locate the unused relay socket at the back of the electrical compartment. Usually white but sometimes black. Jumper the white-red to the blue-black. This will fire the injector as long as the engine is cranking. Will be great when cold, will flood it when hot so don't just leave the jumper in place. DO NOT CONNECT ANYTHING TO THE BLACK (ground) wire or you will melt things. Some folks wire this as a push-button to avoid replacing the thermotime switch.


Ok, the cold start valve tests good. So I guess the long cranking on cold start would mean faulty thermotime switch or bad wiring. What am I looking for to test the thermotime switch electrically?
Also, I just want to confirm before ordering a new WUR that the lower control pressure on cold start up closer to spec than the one I have now will make the engine run better until it warms up? It seems to run good when warm, just kinda funky when cold.

[Rich]

It seems to run good when warm, just kinda funky when cold.

Before ordering any parts be sure that the hoses that feed the warmup regulator are all solid. No splits, no cracks? Use an inspection mirror to verify, assuming you can't smoke test them.

A very small split/leak in the hose at a tee leading to the rear fitting on the WUR was causing a stumble during cold acceleration on ours at one point a few years back. After spotting that split I replaced the hose. Solid ever since and still on the original WUR.

[DMCMW Dave]

Before ordering any parts be sure that the hoses that feed the warmup regulator are all solid. No splits, no cracks? Use an inspection mirror to verify, assuming you can't smoke test them.

A very small split/leak in the hose at a tee leading to the rear fitting on the WUR was causing a stumble during cold acceleration on ours at one point a few years back. After spotting that split I replaced the hose. Solid ever since and still on the original WUR.

That won't impact the static pressure though, and his is too high when cold. Still a good thing to check if you have a car that falls on its face when cold.

[skill]

I had a similar issue on a different car. The idle was up and down and everywhere. Cause; High carbon build up internal. I switched out the spark plugs, cleaned (decarbonized) out the plenum, replaced gaskets as necessary and replaced the fuel injectors (and cleaned them one-by-one). It corrected the issue. If someone could tell me, where on the PRV would it have carbon (gunk) build up on this engine?

[Trstno1]

I had a similar issue on a different car. The idle was up and down and everywhere. Cause; High carbon build up internal. I switched out the spark plugs, cleaned (decarbonized) out the plenum, replaced gaskets as necessary and replaced the fuel injectors (and cleaned them one-by-one). It corrected the issue. If someone could tell me, where on the PRV would it have carbon (gunk) build up on this engine?

What is the plenum?

[DMCMW Dave]

What is the plenum?

Intake manifold. I've seen some pretty gunky buildup on DeLorean valves, which is what he's talking about. Not enough to cause a (proven) running issue though. The DMC intake will get dirty but I've never seen any build-up.

This has become a huge issue on modern direct-injection cars as there is no fuel wash on the back of the intake valves. Not so much of a problem since CIS sprays fuel all the time!

[FABombjoy]

For testing the control pressure from cold, the CPR (or WUR as it is sometimes referred to) should be tested with the electrical plug disconnected and the vacuum pipes removed
Yes, this is critical, and reading back through the thread I'm not sure if this was part of the testing that the OP performed:


3. Control Pressure "WARM" (Regulator temp above 40c)

a. Test with Intake manifold vacuum disconnected from control pressure regulator: 3.4-3.8 Bar
b. Connect vacuum pump to vacuum port on control pressure regulator which contains the delay valve: 1 .4-1.8 Bar
Vacuum Setting Value: 450-550 mbar (13.3-16.2 in Hg)


That won't impact the static pressure though, and his is too high when cold. Still a good thing to check if you have a car that falls on its face when cold.
If only the upper chamber sees vacuum wouldn't this be the result? Seems like this could be related to the vac plumbing still. VDV backwards or blocked?

I know that if the lower chamber develops a leak you'll get a huge lean spike on throttle.

[Trstno1]

Yes, this is critical, and reading back through the thread I'm not sure if this was part of the testing that the OP performed:




If only the upper chamber sees vacuum wouldn't this be the result? Seems like this could be related to the vac plumbing still. VDV backwards or blocked?

I know that if the lower chamber develops a leak you'll get a huge lean spike on throttle.

I did unplug the WUR when cold start tested and still recievied 40 psi control pressure upon startup. I was curious about the vacuum as well. I did replace all of the lines when I had the manifold off, but I checked them 3-4 times for correctness prior to putting it all back together. I gues the large unknown is just how the vacuum solinoid and vacuum delay should be working. Should I be able to blow through the vacuum delay valve? I have verified it to be oriented the right way with the white side facing the front of the car.

[FABombjoy]

I did unplug the WUR when cold start tested and still recievied 40 psi control pressure upon startup.
Unplugged... the power? The vacuum? :D

The electrical is for the heater on the bimetallic arm and it's effects are slow. You want it disconnected during a cold test so the CP doesn't start slowly creeping upwards during the test.

With vac removed, if you have high cold and good hot (also high) then could be a clogged filter screen?

I have mercilessly dinked around with my WUR but I've not had to troubleshoot much in the realm of non-user induced faults. But based on how it works, errant vacuum signals could have significant effects on control pressure. Taking measurements with vac disconnected can at least cut the troubleshooting tree in half.

Vac solenoid is for ignition advance. If you hook the lines up backwards your car will hold revs for no good reason.

Testing the delay valve is easy:
http://www.justanswer.com/uploads/Autotechguru/2007-07-20_185259_ford_f150_emissions_930001.pdf
"Spark delay valve" or VDV is the type we have, not the two-way type.

[Bitsyncmaster]

I know that if the lower chamber develops a leak you'll get a huge lean spike on throttle.

You always get a lean spike on all engines with a throttle punch. The throttle plates open to let in air and before the fuel can react it will spike lean. I've recorded AFR from my wideband and you can always see on the plots when the throttle was opened. It will go rich when it's shut.

[FABombjoy]

You always get a lean spike on all engines with a throttle punch.
I did write that funny, really is should read: If you have a vac leak to the lower chamber your AFRs will go continuous > 18:1 on throttle, making the car nearly undriveable until the vacuum control valve switches off the vacuum (and switches on the vac distributor advance).

When I opened up the cover on the WUR adjustment screw to adjust control pressure, I forgot to seal the hole. My car would start fine, idle fine, and drive terribly for the first 2 minutes of warmup. A penny and high-temp silicone seals the hole perfectly :D

[Trstno1]

Unplugged... the power? The vacuum? :D

The electrical is for the heater on the bimetallic arm and it's effects are slow. You want it disconnected during a cold test so the CP doesn't start slowly creeping upwards during the test.

With vac removed, if you have high cold and good hot (also high) then could be a clogged filter screen?

I have mercilessly dinked around with my WUR but I've not had to troubleshoot much in the realm of non-user induced faults. But based on how it works, errant vacuum signals could have significant effects on control pressure. Taking measurements with vac disconnected can at least cut the troubleshooting tree in half.

Vac solenoid is for ignition advance. If you hook the lines up backwards your car will hold revs for no good reason.

Testing the delay valve is easy:
http://www.justanswer.com/uploads/Autotechguru/2007-07-20_185259_ford_f150_emissions_930001.pdf
"Spark delay valve" or VDV is the type we have, not the two-way type.


I know I unplugged the electrical portion of the WUR, Though I am now questioning if I pulled the vacuum hose off too. I'll have to hook up the pressure gauge again and disconnect everything from the WUR and cold start it just to make sure the pressure is still high. I would rather it be a mistake in testing than my wallet being $200 lighter.....

If I confirm I still have 40 psi cold starting control pressure, I replace the WUR Correct? If I have normal cold starting psi without anything connected then it safe to assume have something wonky going on with the vacuum system right?

[FABombjoy]

I know I unplugged the electrical portion of the WUR, Though I am now questioning if I pulled the vacuum hose off too. I'll have to hook up the pressure gauge again and disconnect everything from the WUR and cold start it just to make sure the pressure is still high. I would rather it be a mistake in testing than my wallet being $200 lighter.....

If I confirm I still have 40 psi cold starting control pressure, I replace the WUR Correct? If I have normal cold starting psi without anything connected then it safe to assume have something wonky going on with the vacuum system right?
I know I would test w/ vac disconnected just to be sure. I would also do the warm tests using the vacuum pump just to see what the results are.

If you are the type that likes to tinker both cold & warm pressures are adjustable and rebuild parts are available, but I don't feel qualified enough to write a comprehensive guide.

[Trstno1]

I know I would test w/ vac disconnected just to be sure. I would also do the warm tests using the vacuum pump just to see what the results are.

If you are the type that likes to tinker both cold & warm pressures are adjustable and rebuild parts are available, but I don't feel qualified enough to write a comprehensive guide.

https://youtu.be/mMcAa-yobTg

Here is the video of the test for control pressure with the electrical and vacuum pulled from the WUR. Looks like a little over 30 psi..... Does this warrant WUR replacement or is it just a sign it may be going out? Remember I just replaced a seized ISM that was 3/4 closed.

After the video was taken I hooked up the vacuum and electrical to the WUR and it slowly climbed to 50 psi until it stabilized.

On a side note i did test the cold start valve in a jar while plugging the pipe hole with one finger and someone cranking the starter. The cold start valve sprayed fuel until the engine started and the key was let go from cranking. So now I know the thermotime switch and cold start valve is good.
I don't have a vacuum gauge but just blew into th vacuum delay valve and noticed when I blew from the black side air passes, but if I blow from the white side it feels restricted. This is normal right?

[FABombjoy]

The graph in the manual isn't very precise, but at what you're showing on the gauge for a dead-cold car would be normal if the ambient temp was between about.. 55-70 degrees or thereabouts?

Your VDV test sounds about right.

To follow the vacuum port test to the letter you do need a handheld vac pump or some other source with a gauge so you can set it at 13-16 in/Hg. You could probably just tap it into manifold vac and see if it drops to around the 1.4-1.8 spec'd in the manual (from the 3.4-3.8 warm control pressure).

[Trstno1]

The graph in the manual isn't very precise, but at what you're showing on the gauge for a dead-cold car would be normal if the ambient temp was between about.. 55-70 degrees or thereabouts?

Your VDV test sounds about right.

To follow the vacuum port test to the letter you do need a handheld vac pump or some other source with a gauge so you can set it at 13-16 in/Hg. You could probably just tap it into manifold vac and see if it drops to around the 1.4-1.8 spec'd in the manual (from the 3.4-3.8 warm control pressure).

Yup, I think the temp in the garage is at 60 degrees. So the WUR is good! Yayy! That saves me some money. I really appreciate the help!!

[FABombjoy]

Yup, I think the temp in the garage is at 60 degrees. So the WUR is good! Yayy! That saves me some money. I really appreciate the help!!
Do that warmed up vacuum test first then you can celebrate [emoji1]

[Trstno1]

Do that warmed up vacuum test first then you can celebrate [emoji1]

Will do. I have the vacuum gauge on order now. Though I must admit without touching the accelerator on cold start up, the car will crank for a little bit prior to starting and the hunt pretty bad for a minute prior to calming down at 775 rpm. Then just run a little lumpy.

Any other things this could be? Cold start valve tested good. It sprays fuel when cranking starter and shuts off once starter is not engaged anymore. Could this simply be a fuel injector issue?

[FABombjoy]

Gauge or pump? One of those Mightyvac (or similar) hand pumps is what you're looking for. They're useful for other things too.

In the mean time you could at least verify that the upper and lower chambers hold vacuum by running a line to each, sucking the air out, and seeing if it holds.

With the WUR ruled out you'll then venture off into other parts of the system that I don't have a lot of experience with but others do.

[Trstno1]

Gauge or pump? One of those Mightyvac (or similar) hand pumps is what you're looking for. They're useful for other things too.

In the mean time you could at least verify that the upper and lower chambers hold vacuum by running a line to each, sucking the air out, and seeing if it holds.

With the WUR ruled out you'll then venture off into other parts of the system that I don't have a lot of experience with but others do.

Could you show me a pic of the pump you are talking about?

[FABombjoy]

Could you show me a pic of the pump you are talking about?
I'm on mobile right now, but if you Google Mightyvac you'll see what I mean

[Trstno1]

I'm on mobile right now, but if you Google Mightyvac you'll see what I mean

Ok, got the pump. Where exactly do you hook it up? And how exactly do you connect the test? What are the desired results?

[FABombjoy]

Ok, got the pump. Where exactly do you hook it up? And how exactly do you connect the test? What are the desired results?
Just run some vac hose between the pump and the lower chamber on the WUR. The other vac connection should be open and unobstructed during this test. When the car is warm and the control pressure gauge reads the warm temp pressure, apply about 15in/Hg vacuum to the WUR and note the control pressure reading. This will enrich the mixture and your car will run rough but shouldn't stall.

[Trstno1]

Just run some vac hose between the pump and the lower chamber on the WUR. The other vac connection should be open and unobstructed during this test. When the car is warm and the control pressure gauge reads the warm temp pressure, apply about 15in/Hg vacuum to the WUR and note the control pressure reading. This will enrich the mixture and your car will run rough but shouldn't stall.

Ok- I'm trying to wrap my head around this, would these be the steps I need to take? Sorry to be dense on this one I just don't want to screw it up....

so I should keep the vacuum and electrical both hooked up on the WUR until I get the 3.5 bar of control pressure when the engine is warm.

Then I disconnect both the WUR vacuum lines. Hook up the vacuum pump to the lower chamber while the upper chamber has nothing connected to it. Leave the electrical connection connected to WUR.

Apply 15 in/Hg vacuum to WUR and note the control pressure reading.

this should all take place with the engine running-

What control pressure am I looking for / not looking for?

[FABombjoy]

That's pretty much it. I'd disconnect the vac lines when cold just for convenience. Be sure to plug the vac line coming from the under the intake manifold or it'll run rough from the vacuum leak.

When hot do the test with the pump and check the manual (or my earlier post) for what control pressure should then read.

[Trstno1]

That's pretty much it. I'd disconnect the vac lines when cold just for convenience. Be sure to plug the vac line coming from the under the intake manifold or it'll run rough from the vacuum leak.

When hot do the test with the pump and check the manual (or my earlier post) for what control pressure should then read.

Ok.

So after warm control pressure test I get 1.6 bar which right in the middle of the manuals 1.4-1.8 bar. So, results are that the WUR is good.

Hmmmmm, do you think the vacuum control valve taking longer than the 10-12 seconds the manual states to bleed down is an issue? Mine comes in at a little over 16 seconds to bleed from 16hg to 8 Hg.

I guess next up would be smoke test to find any vacuum leaks.....

[FABombjoy]

Vacuum enrichment is only active when you hit the throttle. If it ran rough while the vac lines were disconnected and the line from under the intake was capped, your problem lies elsewhere. I don't think it's the VDV.

With as hard as it is to start and if it isn't afterfiring or producing black smoke, I'd think you were lean (vacuum leak or misadjusted CO) but then typically you'd see up to 100% duty cycle on the dwell meter test. I'm thinking a misfiring plug, bad injector, fuel distributor issue, even a valve/piston issue, etc.

If it's been going on long enough you may be able to read the spark plugs and see which one(s) it is. If it were my engine this is what I'd probably do. Pull a few and see how they look compared to spark plug chart.

The only time I've made my own engine run genuinely rough through misadjustments was when converting to MSD ignition. I had the hall effect pickup wired backwards and the timing was waaaaaaaaay out in left field. Like instead of reading the marks between 12 o'clock & 1 o'clock on the crank pulley, they were reading somewhere around 9-10 o'clock. The motor sounded like a Harley and wasn't thrilled about revving. I reversed the wires and it went back to happy & normal.

[Trstno1]

Vacuum enrichment is only active when you hit the throttle. If it ran rough while the vac lines were disconnected and the line from under the intake was capped, your problem lies elsewhere. I don't think it's the VDV.

With as hard as it is to start and if it isn't afterfiring or producing black smoke, I'd think you were lean (vacuum leak or misadjusted CO) but then typically you'd see up to 100% duty cycle on the dwell meter test. I'm thinking a misfiring plug, bad injector, fuel distributor issue, even a valve/piston issue, etc.

If it's been going on long enough you may be able to read the spark plugs and see which one(s) it is. If it were my engine this is what I'd probably do. Pull a few and see how they look compared to spark plug chart.

The only time I've made my own engine run genuinely rough through misadjustments was when converting to MSD ignition. I had the hall effect pickup wired backwards and the timing was waaaaaaaaay out in left field. Like instead of reading the marks between 12 o'clock & 1 o'clock on the crank pulley, they were reading somewhere around 9-10 o'clock. The motor sounded like a Harley and wasn't thrilled about revving. I reversed the wires and it went back to happy & normal.

Yeah.... this dang thing is starting to kick my butt. I am going to order new injectors next and see what happens.... Man, I hope I don't have a valve or piston issue. I did conduct a compression test and they came back mostly good. I did have one cylinder that was a little lower than the others but nothing bad.

[Trstno1]

Hey guys -

So I finally shelled out for new injectors and I cant be happier!! The spray pattern on these new 022's from DMCMW are 100% better than the ones I had professionally cleaned! The better part is that my engine vibration is almost completely gone! Check out this video:

https://www.youtube.com/watch?v=cs7iDYuHhXY

The issue that still remains:

- I still do have a bit of a cold start issue where the car wants to crank 4-7 seconds before firing up, then it will hunt pretty good for the next minute until it warms up and settles at 775 RPM. I understand the hunting upon start up is normal depending on the ambient temperature but the excess crank time prior to engine start seems excessive when comparing how my car cold starts vs. others I have seen on youtube. Though it should be known that it starts like a champ immediately when ever the car is warm. Is it possible to get it to act the same way when cold?

I have tested the cold start valve and thermo-time switch operation and all seems nominal there. The WUR tested good, though maybe the cold start control pressure was a little higher than normal. Is there anything else that could cause the cold start issue? Failed rest pressure? vacuum leak(s)?

As always, thanks everyone for your help!

[Bitsyncmaster]

I know when my engine needs the CSV to start because it takes one second of cranking to fire. I use my "hot start" relay to fire the CSV and have no thermal time switch connected. Now I probably don't have the cold temps you do but if my car sits for a week or more, it needs the CSV to start.

Now why your car takes 5 to 7 seconds of cranking to start. My guess would be it's fuel related since that long cranking is just letting the CSV keep priming with some gas.

[Trstno1]

I know when my engine needs the CSV to start because it takes one second of cranking to fire. I use my "hot start" relay to fire the CSV and have no thermal time switch connected. Now I probably don't have the cold temps you do but if my car sits for a week or more, it needs the CSV to start.

Now why your car takes 5 to 7 seconds of cranking to start. My guess would be it's fuel related since that long cranking is just letting the CSV keep priming with some gas.

Is there a chance that the CSV is not injecting enough fuel? I have witnessed it spraying into a jar when cold and plugging my finger over the CSV inlet. What I don't know is if it's actually injecting enough fuel into the intake. How much fuel should it spray in comparison with that of a fuel injector?

Shouldn't I be able to test it by unplugging the CSV and pressing down on the air inlet plate to inject fuel into the cylinders while the pump is priming prior to crank? I would assume that if it fired right off then it would be an issue of fuel quantity coming from the CSV right?

[Bitsyncmaster]

Is there a chance that the CSV is not injecting enough fuel? I have witnessed it spraying into a jar when cold and plugging my finger over the CSV inlet. What I don't know is if it's actually injecting enough fuel into the intake. How much fuel should it spray in comparison with that of a fuel injector?

Shouldn't I be able to test it by unplugging the CSV and pressing down on the air inlet plate to inject fuel into the cylinders while the pump is priming prior to crank? I would assume that if it fired right off then it would be an issue of fuel quantity coming from the CSV right?

It is not much fuel flow from the CSV. I have stuck it in a jar to test it and the amount of fuel is much less than the normal injector. I never though to test if the pressing the air plate increased the flow.

[FABombjoy]

- I still do have a bit of a cold start issue where the car wants to crank 4-7 seconds before firing up, then it will hunt pretty good for the next minute until it warms up and settles at 775 RPM.
Just to be sure - is this behavior consistent now? Whenever I've opened up my fuel system or the car has sat for a long time it always takes a bit longer for the first start. After you changed injectors I wouldn't be surprised to see a delayed startup on your first try, but the next day have a much quicker cold start.

[DMCVegas]

In the Owner's Manual, the instructions clearly states that when cranking, you want to hold the Accelerator Pedal down ¼ of the way. Now, people have argued with me for years that's incorrect, because it *probably* was just copy/pasted from a carbureted PRV manual.

BUT take a look at this: Volvo in their Owner's Manual has instructions that state: If the engine does not start at once, depress the throttle pedal half way and keep it there until the engine starts.

http://new.volvocars.com/ownersdocs/1983/1983_760_GLE/83760_03.htm

The fuel system diagram doesn't *look* like the CSV should be affected by the throttle plate, but holding down the throttle pedal would eat least allow the upper and lower chambers of the Fuel Distributor to fill more quickly as the plate is then depressed from the inbound air, and the plunger slides open.

I've always noticed I've had longer cranks when starting the engine when leaving the pedal alone. EFI Injectors not only run at lower pressures, but also are designed to flow enough additional fuel during cold starts that an additional injector isn't needed. That's why you needn't press the pedal when cranking a modern car. But if even Volvo is telling owners to hold the pedal down during cranking, it absolutely affects starting.

[Morpheus]

Tons of useful info in this thread. I have my own WUR issues to troubleshoot, but I will start with cleaning it first and see where that gets me.