Engine Running Rich

[Ricker]

38472

Ok. I've checked about everything I can think of without really finding anything wrong. Fuel injectors clean and checked, idle 775 RPM, timing good, new micro-switch, filters, spark plugs, wires, rotor & rotor cap, high voltage coil, all vacuum hoses replaced. It has not passed the Colorado Emissions testing. The old spark plugs were all black. From this I assume it is running rich. In addition the car was initially sold in IN. It is now 5,280 feet in CO. I have read a number of posts on how to adjust the mixture; basically checking the dwell of the Frequency Valve (swigging between 30 - 50, average 40) when the engine is idling and running at temperature. But I'm not sure where or how to get to the mixture screw. I believe it is under the cap centered in front of the Fuel Distributor (toward the rear of the car).

So for "fuel adjustments for dummies", is this the right thing? How do I get the cap off? Is it screwed in? I think it is pressed in or what? Can I just grab it with some pliers and pull? Can I get a screw driver under it and pry? I believe a long 3 mm Allen Wrench is used for the adjustment. What do I get to plug it up with afterwards?

Next, how and specifically where do I connect the dwell meter up to? Does anybody have pictures?

If this is set right my next replacement is the Catalytic converter.

I really want to be able to do this and understand it. Driving to Texas or finding a local garage is my next choice.

Thanks!

[sdg3205]

You'd have to carefully drill it out.

Before you do, you need to confirm your lama system is actually working. It may be that it isn't, in which case that would be your first step.

Does the frequency valve buzz? if you unplug it, does it throw off your idle?

[Ricker]

Yes. It buzzes and if you disconnect the wire the idle is terrible.

[DMCMW Dave]

You'd have to carefully drill it out.

?

DO NOT just drill it out. People do this and damage the housing. You need to drill a small hole in the center of that plug and STOP when it hits the steel disc at the bottom of the aluminum plug. Then thread in a sheet metal screw and use that to pull the plug out.

If you try to drill through it, you can round out the hole to be too big for a plug, get metal shavings in the engine, or drill through and damage the adjuster. Or all three on the same car!

[sdg3205]

thats a good sign.

check mixture with a dwell meter. stick the probes in the molex connector at the bulkhead with the car at operating temp and see what you get.

[sdg3205]

DO NOT just drill it out. People do this and damage the housing. You need to drill a small hole in the center of that plug and STOP when it hits the steel disc at the bottom of the aluminum plug. Then thread in a sheet metal screw and use that to pull the plug out.

If you try to drill through it, you can round out the hole to be too big for a plug, get metal shavings in the engine, or drill through and damage the adjuster. Or all three on the same car!

hence the word "carefully." figured we'd cross that bridge if it became necessary.

EDIt - Dave, I also would not try and give advice on something I have never actually done. That's all you!

[Ricker]

I think before I go through the trouble to removing the plug, I will check the reading. Perhaps it is something else and I'll get out of doing it. I need to go get a dwell meter. I still do not understand how or where to hook it up to. Maybe once I get the meter I will understand better. Sometimes I can't see the obvious.

[Bitsyncmaster]

I think before I go through the trouble to removing the plug, I will check the reading. Perhaps it is something else and I'll get out of doing it. I need to go get a dwell meter. I still do not understand how or where to hook it up to. Maybe once I get the meter I will understand better. Sometimes I can't see the obvious.

Yes, get the meter first before you drill the plug. There are a few ways to read the dwell. Make sure you check your reading by pressing the wide open throttle switch. Your reading should be very close to 55 deg. If not your meter is hooked up wrong.

[Ron]

I think before I go through the trouble to removing the plug, I will check the reading. Perhaps it is something else and I'll get out of doing it. I need to go get a dwell meter. I still do not understand how or where to hook it up to. Maybe once I get the meter I will understand better. Sometimes I can't see the obvious.

Here Ya Go:

How To: Set Dwell (http://dmctalk.org/showthread.php?12909-How-To-Set-CO-Dwell&p=186216#post186216)
How To: Remove Anti-Tamper CO Plug (http://dmctalk.org/showthread.php?8362-Removing-the-anti-tamper-plug-covering-the-mixture-adjustment-screw)

[Jonathan]

So for "fuel adjustments for dummies", is this the right thing? How do I get the cap off? Is it screwed in? I think it is pressed in or what? Can I just grab it with some pliers and pull? Can I get a screw driver under it and pry?

38520

See if you can open this attachment. It is section D from the workshop manual, the fuel and emissions section. It explains in section D:04:03 what to do with the tamper proof cap (page 23 of 46 in the PDF file).


I believe a long 3 mm Allen Wrench is used for the adjustment. What do I get to plug it up with afterwards?

You can use a golf tee to plug it afterwards or a wad of bubble gum, or get one of these from DMCH:

http://store.delorean.com/p-6399-plug-removeable.aspx


Next, how and specifically where do I connect the dwell meter up to? Does anybody have pictures?

Have a look at this short video.


https://www.youtube.com/watch?v=cpNB1eRktzM

I think the consensus was that Bob's dwell reading wasn't right since the needle generally isn't supposed to stay stuck on 43 like it is in the clip, but it does show you clearly where and how to hook it up.

If you look through that workshop manual section, on page 35 of 46 (D:04:15) explains the testing steps to ensure your Lambda system is doing what it is supposed to be doing. If you go ahead and do that stuff, please share your results as I have done those tests before myself and wasn't too clear on what the results told me.

[David T]

If it is running REALLY rich the catalytic converter and the muffler will glow red. Usually because the fuel plunger is stuck in the Fuel Distributor. With the motor running do you feel a resistance when you push down on the air sensor plate? If not, the plunger is stuck. No amount of adjustment is going to overcome that. Generally if the tamperproof plug is still there your mixture is probably very close to where it should be and there is another reason why it is running rich. Get a meter on the motor before trying to get that plug out and see what the readings are. It is possible it won't go into "closed loop" because the O2 sensor is bad and that is why it is running rich.

[opethmike]

That's some excellent guru-ing.

[Ricker]

38712

Ok. I'm replacing the fuel injection lines so I think I want to remove the adjustment plug while I have everything tore apart. I've tried to drill the aluminum plug but it seems there is steel in the way. Nothing to get a screw into. My next step is to remove the Mixture Control Unit, flip it over and then punch out the plug, I hope. Can you tell me if the flat plate in the picture is part of the plug or does it stay?

I've watch some videos and re-read what you have said. Makes perfect sense now.

Can't thank you enough for the help!

[Denver DMC]

Rocky Mountain DeLoreans has a proper gas analyzer at its shop at Jackson and 41st in Denver and strong experience tuning cars, which is much more efficient than a dwell meter. Call us. Dan Haney, Matt Crabtree, and 10 others.

Send me a pm.

Peter Moore


Sent from my iPhone using Tapatalk

[Bitsyncmaster]

38712

Ok. I'm replacing the fuel injection lines so I think I want to remove the adjustment plug while I have everything tore apart. I've tried to drill the aluminum plug but it seems there is steel in the way. Nothing to get a screw into. My next step is to remove the Mixture Control Unit, flip it over and then punch out the plug, I hope. Can you tell me if the flat plate in the picture is part of the plug or does it stay?

I've watch some videos and re-read what you have said. Makes perfect sense now.

Can't thank you enough for the help!

The flat plate stays. Hard to see much else in your photo but if your removing the mixture unit and going to split the halfs, you should be able to punch the plug out from the inside.

[David T]

The flat plate stays. Hard to see much else in your photo but if your removing the mixture unit and going to split the halfs, you should be able to punch the plug out from the inside.

Once you remove the bottom half you have to remove the air sensor plate and lever arm so you can punch the plug out. Do not allow the plunger to fall out and get damaged.

[PJ Grady Inc.]

The flat plate stays. Hard to see much else in your photo but if your removing the mixture unit and going to split the halfs, you should be able to punch the plug out from the inside.

You should have used a 1/8" bit as now you have no material for the screw to bite into as Dave was suggesting. Time now to split the housing and use a shortened nail as the workshop manual procedure describes.
Rob

[David T]

You should have used a 1/8" bit as now you have no material for the screw to bite into as Dave was suggesting. Time now to split the housing and use a shortened nail as the workshop manual procedure describes.
Rob


That procedure is in the Workshop Manual at D:04:03. It isn't easy to do. I found it easier to just take the whole thing apart. You do need a circlip tool and you have to be careful with the spring. Then you have to center the arm again after you are done. It also allows you to clean the fuel plunger.

[Ricker]

Rocky Mountain DeLoreans has a proper gas analyzer at its shop at Jackson and 41st in Denver and strong experience tuning cars, which is much more efficient than a dwell meter. Call us. Dan Haney, Matt Crabtree, and 10 others.

Send me a pm.

Peter Moore


Sent from my iPhone using Tapatalk

Peter:

I am working on a ton of things including the brakes, windows and seats, I'll be getting in touch with you but it may be sometime early next year. Glad to have DeLorean experience so close.

Rick

[Ricker]

Well I've gotten the plug out. Split the unit and made a tool like in the manual out of a nail. No need to take out anything else. Actually it was pretty simple, just a bit of time. Now to finish up the rest of the fuel lines replacements including the filter. It's a bit cold out here in Denver so it might be a little while.

[David T]

Well I've gotten the plug out. Split the unit and made a tool like in the manual out of a nail. No need to take out anything else. Actually it was pretty simple, just a bit of time. Now to finish up the rest of the fuel lines replacements including the filter. It's a bit cold out here in Denver so it might be a little while.


Don't forget, now that you have the plug out you must put a removable plug back in or the motor won't run well at all. Remove it only to adjust the mixture screw and when you adjust the mixture screw you do it in very small increments and then immediately replace the plug to see how it runs.

[Ricker]

I finally have the engine back together and running. I checked the RPM and it is +/-775 engine hot or cold but WITHOUT the micro switch contacted. With it when cold it "hunts" just a small bit, hot a whole bunch, I mean a whole bunch.

The idle/low speed motor, cold start valve and frequency valve all vibrate. Disconnect the idle/low speed motor or frequency valve and the engine runs different. Disconnect the cold start valve and nothing changes

The dwell reading when hot and no micro switch it was a steady 52 (26 on the 8 cylinder scale). I turned it counterclockwise a hair and it when to 20 (10 on the 8 cylinder scale). Tried to turn it clockwise to get it to 40 and now it will not move.

When I bought the car the micro switch was not connected and it ran fine. I got a new idle/low speed motor and connected the micro switch and it ran fine just couldn't pass emissions.

Another note, when it runs the exhaust smells really bad. I think like CO.

No idea what to do or which way to go.

[Ron]

The dwell reading when hot and no micro switch it was a steady 52 (26 on the 8 cylinder scale).What is it with the Micro Switch connected and adjusted correctly??

This could be caused by the Full Throttle Switch (WOT) stuck shut, its wiring shorted to ground, a bad Thermal Switch, or its wiring shorted to ground. [Both fed to ECU pin 7 via LG wire]


I turned it counterclockwise a hair and it when to 20 (10 on the 8 cylinder scale). Tried to turn it clockwise to get it to 40 and now it will not move.Sounds like it is out of range -- I think it is touchier than you may think. (I.E. you should have turned it 1/4 of a hair ;-)


Another note, when it runs the exhaust smells really bad. I think like CO.
....52 when hot would be rich.


No idea what to do or which way to go.
Hook the Micro Switch back up and start over...turn the CO adjustment as little as you can each time, plug the hole, rev it a little*, then allow it to settle for a few seconds before taking a reading.
(* I've noticed that sometimes the meter will just sit there a long time otherwise, if the setting was way off....)

[Ricker]

What is it with the Micro Switch connected and adjusted correctly??

This could be caused by the Full Throttle Switch (WOT) stuck shut, its wiring shorted to ground, a bad Thermal Switch, or its wiring shorted to ground. [Both fed to ECU pin 7 via LG wire]

Sounds like it is out of range -- I think it is touchier than you may think. (I.E. you should have turned it 1/4 of a hair ;-)


....52 when hot would be rich.


Hook the Micro Switch back up and start over...turn the CO adjustment as little as you can each time, plug the hole, rev it a little*, then allow it to settle for a few seconds before taking a reading.
(* I've noticed that sometimes the meter will just sit there a long time otherwise, if the setting was way off....)

Well I went back out to do some checking and adjustments you commented on. Now it won't hold a steady RPM and that is before I connect the micro switch. I just put on all new vacuum hose so I don't think that is it.

[fnzen]

So Ill share some of my experience

previously car was maintained by someone that thought they knew what they were doing but it was a gross polluter when I had to get it smogged and ran kinda crappy, had fuel pump changed /all fuel hoses/filter, still ran rich

Heres what I did:
changed cap/rotor/wires/plugs/vacuum solenoid/seal for the idle pipe ....at this point it was hunting bad because the mixture screw was too rich..adjusted it so it didnt hunt
had it sniffed and was still a gross polluter HOWEVER the smog station owner was an old volvo/porsche guy so he started to adjust the microswitch, idle and mixture screws WHILE ON SMOG ANALYZER , dialed it in but still needed a cat and O2 sensor

brought it back after installing cat and sensor and it passed like it was brand new

MORAL bring the car to a shop that can analyze with a smog pipe sniffer anything else will just cause grief

[David T]

Actually the take-away lesson is to find a person or a shop that knows what they are doing and has the equipment to do it properly if you won't (or can't) do it yourself. This forum through the knowledge and experience of it's many members tries to give you FREE the expertise necessary to do this kind of stuff. Not everyone is comfortable doing it or has the equipment necessary to do it right. At least you can know what has to be done and will know when it is done right. Also California is a special case in that they are so strict with their emissions rules. Most States either don't test older cars or they only test them to the standards that they had to pass when they were made. The good news is that Deloreans were VERY clean running cars for the standards of their time, a time when just about every other car had a carburetor and polluted much more than a fuel injected car!

[Ricker]

So Ill share some of my experience

previously car was maintained by someone that thought they knew what they were doing but it was a gross polluter when I had to get it smogged and ran kinda crappy, had fuel pump changed /all fuel hoses/filter, still ran rich

Heres what I did:
changed cap/rotor/wires/plugs/vacuum solenoid/seal for the idle pipe ....at this point it was hunting bad because the mixture screw was too rich..adjusted it so it didnt hunt
had it sniffed and was still a gross polluter HOWEVER the smog station owner was an old volvo/porsche guy so he started to adjust the microswitch, idle and mixture screws WHILE ON SMOG ANALYZER , dialed it in but still needed a cat and O2 sensor

brought it back after installing cat and sensor and it passed like it was brand new

MORAL bring the car to a shop that can analyze with a smog pipe sniffer anything else will just cause grief

When I had it apart I did notice that the idle pipe that goes into the bottom half of the mix unit fit is loose - no gasket or O-ring. I looked at the Manuel and can't seem to find a part for it. Hast to be one it is a big air leak. Any idea what should be there?

I was hoping to get to the point where I got the adjustments close and then take it to someone with a smog analyzer. I don't want to replace things that are still good. By now that is just the cat.

[fnzen]

When I had it apart I did notice that the idle pipe that goes into the bottom half of the mix unit fit is loose - no gasket or O-ring. I looked at the Manuel and can't seem to find a part for it. Hast to be one it is a big air leak. Any idea what should be there?

I was hoping to get to the point where I got the adjustments close and then take it to someone with a smog analyzer. I don't want to replace things that are still good. By now that is just the cat.

The hole in the fuel distribution housing where the pipe goes should have a "brass" ring that press fits/holds a rubber o ring gasket that "seals" the pipe entry into the housing it should "feel" tight , that is a large source of vacuum leak.

The diagram doesnt show the o ring ???

https://store.delorean.com/c-338-2-5-0-motorecumicroswitch.aspx

The pipe 21 can be used to "fit" an o ring if you dont have the old o ring

[Ricker]

Actually the take-away lesson is to find a person or a shop that knows what they are doing and has the equipment to do it properly if you won't (or can't) do it yourself. This forum through the knowledge and experience of it's many members tries to give you FREE the expertise necessary to do this kind of stuff. Not everyone is comfortable doing it or has the equipment necessary to do it right. At least you can know what has to be done and will know when it is done right. Also California is a special case in that they are so strict with their emissions rules. Most States either don't test older cars or they only test them to the standards that they had to pass when they were made. The good news is that Deloreans were VERY clean running cars for the standards of their time, a time when just about every other car had a carburetor and polluted much more than a fuel injected car!

Yea, it's about time to go to someone that know what they're doing.

[PJ Grady Inc.]

When I had it apart I did notice that the idle pipe that goes into the bottom half of the mix unit fit is loose - no gasket or O-ring. I looked at the Manuel and can't seem to find a part for it. Hast to be one it is a big air leak. Any idea what should be there?

I was hoping to get to the point where I got the adjustments close and then take it to someone with a smog analyzer. I don't want to replace things that are still good. By now that is just the cat.


You must have that brass ring retainer and the o-ring or that would cause a massive air/vacuum leak. My guess is that someone richened it way up to keep it from stalling at idle but it must be running very rich to sustain an idle under this condition. You have just discovered at least one big problem that requires fixing before moving ahead. The brass ring is not available from DMCH but we have some on hand if you need one.
Come to think of it you're not really that far from us?
Rob

[David T]

You must have that brass ring retainer and the o-ring or that would cause a massive air/vacuum leak. My guess is that someone richened it way up to keep it from stalling at idle but it must be running very rich to sustain an idle under this condition. You have just discovered at least one big problem that requires fixing before moving ahead. The brass ring is not available from DMCH but we have some on hand if you need one.
Come to think of it you're not really that far from us?
Rob

I have seem where someone jammed in a piece of pipe into the mixture unit and then connected it to the idle motor with a piece of hose. Not the prettiest way to do it but it worked. If the brass retainer is not in place it most likely is laying on top of the motor along with the "O" ring. Most of the time when it is not in place, it is there on the pipe rattling around.

[PJ Grady Inc.]

I have seem where someone jammed in a piece of pipe into the mixture unit and then connected it to the idle motor with a piece of hose. Not the prettiest way to do it but it worked. If the brass retainer is not in place it most likely is laying on top of the motor along with the "O" ring. Most of the time when it is not in place, it is there on the pipe rattling around.

A few late VIN cars come this way from the factory. They seal the area more effectively but are a hassle when it comes time to do a tuneup and you want to R&R the A.S. Hsg. If the ring is not loose oncthe pipe then someonr removed it because it got damaged and they either didn't realize it's importance or couldn't locate a replacement but it can't be left that way.
Rob

[Bitsyncmaster]

That pipe feeding the from the idle motor really does not feel that tight with the o-ring and pipe greased as it should be.

[fnzen]

That pipe feeding the from the idle motor really does not feel that tight with the o-ring and pipe greased as it should be.

guess it depends on definition of tightness...but OP stated loose..definitely should not be loose

[Ron]

??? I thought you had all new vacuum hoses...:

I agree with Rob on the symptoms/probable cause(s) at this point.

$.02
Don't give up, "Up-grade it", like the turbos and end the problem while making it all easier to (re)assemble and trust. Get one of these making sure the passage is as large as you can find while fitting new hose and port (epoxy in, or preferably, tap the hole). [Install this end of the hose before or after you set the manifold in place (you can basically see where it goes afterward...then bolt it down. ]

39250

Then (following the "set the CO after ALL other things are correct" rule ;-) double check the other settings (timing, rpm, micro switch settings, other vac leaks, etc) and then set the CO. If that don't cure it, then I'd suggest visiting Rob to finish it up.

[PJ Grady Inc.]

??? I thought you had all new vacuum hoses...:

I agree with Rob on the symptoms/probable cause(s) at this point.

$.02
Don't give up, "Up-grade it", like the turbos and end the problem while making it all easier to (re)assemble and trust. Get one of these making sure the passage is as large as you can find while fitting new hose and port (epoxy in, or preferably, tap the hole). [Install this end of the hose before or after you set the manifold in place (you can basically see where it goes afterward...then bolt it down. ]

39250

Then (following the "set the CO after ALL other things are correct" rule ;-) double check the other settings (timing, rpm, micro switch settings, other vac leaks, etc) and then set the CO. If that don't cure it, then I'd suggest visiting Rob to finish it up.
There no way this "fix" would not substantially lower the pipe I.D. possibly causing stalling or idle quality issues. It will also be much harder to R&R the air sensor for servicing. I would suggest sourcing the correct part and keep it simple. Doesn't seem to be much going on in the owners garage recently here anyway so why make the fix more complicated?
Rob

[Ricker]

I did have the brass ring and O-ring but the O-ring looked pretty bad. Tube slid in and out with some slop. Replaced it and put it all back together. Runs now pretty good, in fact good enough to now take it some place close to get a professional to make the adjustments. I believe everything is operating properly.

Now the next thing I noticed. There a three large "screws" right near the throttle body. I thought they are not used and are suppose to be closed. Mine are open. Not sure they do anything.

Always something.

[Bitsyncmaster]

I did have the brass ring and O-ring but the O-ring looked pretty bad. Tube slid in and out with some slop. Replaced it and put it all back together. Runs now pretty good, in fact good enough to now take it some place close to get a professional to make the adjustments. I believe everything is operating properly.

Now the next thing I noticed. There a three large "screws" right near the throttle body. I thought they are not used and are suppose to be closed. Mine are open. Not sure they do anything.

Always something.

All three screws should be closed. Some people have adjusted them but for the stock setup they stay closed.

[fnzen]

I did have the brass ring and O-ring but the O-ring looked pretty bad. Tube slid in and out with some slop. Replaced it and put it all back together. Runs now pretty good, in fact good enough to now take it some place close to get a professional to make the adjustments. I believe everything is operating properly.

Now the next thing I noticed. There a three large "screws" right near the throttle body. I thought they are not used and are suppose to be closed. Mine are open. Not sure they do anything.

Always something.

good job!

[Ron]

There no way this "fix" would not substantially lower the pipe I.D. possibly causing stalling or idle quality issues. It will also be much harder to R&R the air sensor for servicing. I would suggest sourcing the correct part and keep it simple. Doesn't seem to be much going on in the owners garage recently here anyway so why make the fix more complicated?
RobWhen I remove my air sensor I simply unbolt it, unclamp the ISM end of the hose and lift it all out together. To reinstall, I set the air plate in its hole, lean/roll it a bit to the right, run the hose under the left horn, look down the left side of the air sensor and guide the hose on the barb, double check o-rings and torque it down. How that is any harder is beyond me.
As for substantially reducing the pipe ID (passage), I would agree that simply epoxying a nipple inside the existing hole might be too too small, but it only needs to be as big as the largest passage created by the ISM internally,so , without looking-from memory, I believe after drilling and tapping for a thin-wall nipple this would not be a problem -- I have no idle problems, nor do several other turbo systems I've have seen, or other people reporting the same setup in old threads here. I would even say, without a requirement that a hole would have to be drilled on the same center as the original (which does not exist even using the OEM rubber hose) one could almost drill a hole large enough that they could throw the ISM through it (minus the two protruding pipes).

P.S. No more shameless plugs for you.:deviltail:

[Ron]

I thought they are not used and are suppose to be closed.Correctamundo -- Shut them and try the CO.

[Ron]

...even using the OEM rubber hose) Should have said "...OEM pipe and rubber hose..."

[PJ Grady Inc.]

When I remove my air sensor I simply unbolt it, unclamp the ISM end of the hose and lift it all out together. To reinstall, I set the air plate in its hole, lean/roll it a bit to the right, run the hose under the left horn, look down the left side of the air sensor and guide the hose on the barb, double check o-rings and torque it down. How that is any harder is beyond me.
As for substantially reducing the pipe ID (passage), I would agree that simply epoxying a nipple inside the existing hole might be too too small, but it only needs to be as big as the largest passage created by the ISM internally,so , without looking-from memory, I believe after drilling and tapping for a thin-wall nipple this would not be a problem -- I have no idle problems, nor do several other turbo systems I've have seen, or other people reporting the same setup in old threads here. I would even say, without a requirement that a hole would have to be drilled on the same center as the original (which does not exist even using the OEM rubber hose) one could almost drill a hole large enough that they could throw the ISM through it (minus the two protruding pipes).

P.S. No more shameless plugs for you.:deviltail:
Fair enough....seems like an unusual fix but if it works it works! Now about those shameless plugs........
Rob

[Ricker]

Well it has taken some time but I finally got everything running on the engine properly. Thanks to the guys, equipment and know how at the Rocky Mountain DeLorean Club and the LLC in Denver, CO. After setting the air/fuel ratio (it was running very rich) using their four gas analyzer, it does not "hunt", it pass the CO emissions test (not even close) and runs like it is brand new.

Note: With my limited knowledge but what I saw is if your car is "hunting", it needs the air/fuel ratio adjusted by more than a dwell meter.

Now on to the next issue. - the transmission. Do issue ever stop? The pleasures of DeLorean ownership.