Failed Emissions Test, who can figure it out?

[shortcircuit971]

So last year it passed emissions after failing the first time and finding out all that was wrong was two vacuum lines switched for the distributors vacuum advance. Now this year it failed again, but differently.

The first year it failed CO at idle. This year it failed CO at 2500 and passed at idle. Here are the full results of today's emissions test.

_____________2500___________IDLE____________LIMITS
HC PPM_______165.5__________116.2___________220.0____ ____PASS
CO %________2.09____________0.17___________1.20______ ____FAILED
CO2 %_______13.5809_________13.2016
RPM_________2456____________834____________1350___ ______OK

If you can figure out exactly whats wrong and how to test it, I will be eternally grateful. If you have any questions about the details of the car, feel free to ask. I'm hoping someone had the exact same problem out there and can just shout out with confidence the solution. It's an 81 VIN: 3670 w/manual and 34,000 on original engine.

[shortcircuit971]

Update:

The vacuum solenoid works and only allows vacuum to the distributor when the throttle is pushed enough for the idle microswitch to release. Test was done on warm but not fully hot engine. It cooled down a little since I got home but the engine is still too hot to touch. If this points someone in the right direction or you know the next best thing to test, I'm all ears.

[shortcircuit971]

One more thing before I forget. I recently replaced the air filter with a K&N from specialtauto. Before that it had an original 81 filter bought from delorean houston and was decently dirty. I don't know if the increased airflow would make any difference. I did not do any adjustments when I replaced the air filter.

[Bitsyncmaster]

First thing I would do is replace the O2 sensor and then check the mixture with a dwell on the FV.

[bkntym]

High CO means unburt fuel.. so lean it out just an 1/8 th of a turn. take the air intake off. there is a round flap that goes up and down with the gas peddle. right behind the opening there is a hole ( may have a plug in it...actually it should have a plug in it. ) unplug it and use a 1/8th allen key( long one). turn it 1/8th counter clock ( i think) and try that. YOU MUST re plug or cap that hole ...and if its not plugged now thats why you failed so plug it.


Hope that helps. but always check with a mechanic to sure things are right.

[Spittybug]

High CO means unburt fuel.. so lean it out just an 1/8 th of a turn. take the air intake off. there is a round flap that goes up and down with the gas peddle. right behind the opening there is a hole ( may have a plug in it...actually it should have a plug in it. ) unplug it and use a 1/8th allen key( long one). turn it 1/8th counter clock ( i think) and try that. YOU MUST re plug or cap that hole ...and if its not plugged now thats why you failed so plug it.


Hope that helps. but always check with a mechanic to sure things are right.

While this MAY be a solution, DON'T do it until you have tried the previous post! Idle mixtures don't just spontaneously go out of whack. O2 sensors do however peter out. It is a slippery slide when you start playing with mixture without ruling everything else out.

[DMCMW Dave]

While this MAY be a solution, DON'T do it until you have tried the previous post! Idle mixtures don't just spontaneously go out of whack. O2 sensors do however peter out. It is a slippery slide when you start playing with mixture without ruling everything else out.

Well put. The CO adjustment, while very twitchy at idle, is does relatively little at speed. You are just likely to screw up the idle CO as actually to actually fix anything.

Do you feel any engine miss at higher RPM?

Have you put a dwell meter or fuel pressure gauge on the engine so you can really tell what it's doing? Diagnostics by turning knobs and throwing parts on an engine is expensive and frustrating.

[shortcircuit971]

YOU MUST re plug or cap that hole ...and if its not plugged now thats why you failed so plug it.

The hole was drilled out by the PO and so I plugged the hole with the houston part almost a year and a half ago.



While this MAY be a solution, DON'T do it until you have tried the previous post! Idle mixtures don't just spontaneously go out of whack. O2 sensors do however peter out. It is a slippery slide when you start playing with mixture without ruling everything else out.

I did have to adjust the idle mixture when I bought the car because it was way off and was missing a plug for the adjustment hole, but I haven't messed with it since. I'm pretty decent with electronics so I adjusted it with a duty cycle meter after replacing the O2 sensor about 6000 miles ago.

There was however, about 3 months, less then 1000 miles I think, between first replacing the O2 sensor and then fixing the high fuel mixture and unplugged adjustment hole. Could this potentially cause the O2 sensor to work for an emissions test and then fail soon after that? The emissions test was 6 - 9 months after the fuel mixture was finally tuned properly.

[shortcircuit971]

Do you feel any engine miss at higher RPM?

Have you put a dwell meter or fuel pressure gauge on the engine so you can really tell what it's doing? Diagnostics by turning knobs and throwing parts on an engine is expensive and frustrating.

I do not feel any miss at higher RPM, but sometimes a little of a miss at idle. I have not put on a dwell meter or fuel pressure gauge. Do you mean dwell meter for ignition, or for testing the frequency valve? I have a duty cycle meter if its for the frequency valve.

[DMCMW Dave]

I do not feel any miss at higher RPM, but sometimes a little of a miss at idle. I have not put on a dwell meter or fuel pressure gauge. Do you mean dwell meter for ignition, or for testing the frequency valve? I have a duty cycle meter if its for the frequency valve.

I meant on the frequency valve. A duty cycle meter is the same thing - or better! That will tell you what is going on with the Lambda electronics, i.e. is it working, and is it responding to the O2 sensor appropriately.

[shortcircuit971]

I meant on the frequency valve. A duty cycle meter is the same thing - or better! That will tell you what is going on with the Lambda electronics, i.e. is it working, and is it responding to the O2 sensor appropriately.

Perfect I remember doing these tests before, but I also remember it being difficult finding exactly what the readings should be. I understand what the duty cycle refers to and how the frequency valve works. Could you refresh me on which pin on the diagnosis connect on the driver side engine bay is for the frequency valve reading, or if there is a better place to hook up my duty cycle meter? And also what the readings to look for and what they mean and as the engine is warm or cold or open or closed loop etc.? Thank you.

[David T]

If it passed and now is failing something changed. The mixture screw did not move by itself. My guess would be a fouled O2 sensor also but WHY? A very obvious answer is one or more dirty injectors spraying a bad pattern and causing some fuel to pass through the motor not completely burned. Try running a bottle of Techron injector cleaner in a tank of gas. If that doesn't help pull the injectors and have them cleaned and tested. THEN you can check the duty cycle in the Lambda system and if necessary replace the O2 sensor and tweak the mixture screw. The shorter answer is to get antique or historic plates and skip the emissions testing if you can in your State.
David Teitelbaum

[DMCTek]

What is the history on the ignition system. Has it ever been tuned up. If so what plugs and wires are on it?

[Bitsyncmaster]

Dwell (4 cylinder) is 45 degrees at 50% duty cycle.
Dwell (4 cylinder) is 90 degrees at 100% duty cycle.
Dwell (4 cylinder) is 0 degrees at 0% duty cycle.

So Duty cylcle numbers =
(duty % x 0.9) = dwell

[shortcircuit971]

What is the history on the ignition system. Has it ever been tuned up. If so what plugs and wires are on it?

It had a new cap and rotor put in about a year ago right before the first emissions test. The wires and plugs however were put in with the PO so I do not know their age or condition. I figured if they were good enough to pass emissions, they were good enough to not mess with. Now it seems it might be overdue. I will go out and check who made the wires and then I'll pull a plug or two and see the manufacturer and condition.

If the two plugs I pull don't look at least 70% good, then I'll pull all of them and replace them. For the prices of spark plugs I can afford to just replace them so I'll know from now on who put them in, what brand they are, and how old they are.

[Bitsyncmaster]

One thing that can quickly kill the O2 sensor is contamination by silicon. Make sure any sealers you use say sensor safe.

[Ron]

... Could you refresh me on which pin on the diagnosis connect on the driver side engine bay is for the frequency valve reading, or if there is a better place to hook up my duty cycle meter? And also what the readings to look for and what they mean and as the engine is warm or cold or open or closed loop etc.? Thank you.
See section D:04:14 & 15 (in link below), don't forget to use 4cyl if you use a dwell meter.
The Orange wire in the Blue bulkhead connector should also work.
http://dmctalk.org/attachment.php?attachmentid=592&d=1306869922

From what you say, it would be a good idea to just change all of the plugs (first)...too much info to miss if you don't at least look at them all (especially since you have a problem).

[shortcircuit971]

From what you say, it would be a good idea to just change all of the plugs (first)...too much info to miss if you don't at least look at them all (especially since you have a problem).

Which plugs would be a best fit for a stock ignition system, coil, and resistor pack? What would be the best gap to set them at as well?

The whole car is pretty original stock parts as far as fuel, engine, and ignition. I'm not looking to spin tires or anything like that. Just a nice balance between performance and fuel economy.

[Ron]

That is a religious question ;-)

I would stick with the stock Bosch HR6DS .024-.028"

FYI the entire workshop manual is at the same link as above.

[shortcircuit971]

That is a religious question ;-)

I would stick with the stock Bosch HR6DS .024-.028"

FYI the entire workshop manual is at the same link as above.

Lol. So is there any place locally to get the plugs or do I have to order them online? I live in Colorado and have the usual autozone, napa, oreilly, etc. Or would even a dealership carry them?

[shortcircuit971]

After looking at the parts crossover list in the resources section, the closest I could find in stock near me are the ACDelco R44LTS6 plugs. I added a link below. It says the gap is set at 0.060" so I would have to regap them to 0.024-0.028". Are these suitable for long term use as a replacement, or only for emergency use?

http://napaonline.com/Catalog/CatalogItemDetail.aspx?R=AC_R44LTS6_0075293998

[David T]

The problem with trying to get the plugs locally is if they are not in stock the store has to order a box and all you will want is 6. If you can't find them locally and the store has to order them you might get them just as fast ordering them from one of the Delorean vendors who have them in stock. You can also order an extra oil filter or air filter to keep on hand. You really should stay with the Bosch plugs if you can.
David Teitelbaum

[Ron]

After looking at the parts crossover list in the resources section, the closest I could find in stock near me are the ACDelco R44LTS6 plugs. I added a link below. It says the gap is set at 0.060" so I would have to regap them to 0.024-0.028". Are these suitable for long term use as a replacement, or only for emergency use?

http://napaonline.com/Catalog/CatalogItemDetail.aspx?R=AC_R44LTS6_0075293998 Bad idea.
Call your local autopart(s)...and order them if you have to. Most will overnight them, usually free.

[shortcircuit971]

Here is a picture of the spark plug. No the silver bits are not the threads off the engine. I was worried at first but then examined it and found it's some sort of anti-seize. The picture is high-res so if you save it you can zoom in and see them better. I'm not that experienced with reading spark plugs so if someone can chime in with there wisdom and let me know how they look that would be great?

Based on the picture, do you think I can reuse them for now to continue diagnosis and pass emissions? Thanks.

The order of the plugs are based on the factory firing order and are as follows.
3----------6
2----------5
1----------4

http://i297.photobucket.com/albums/mm216/shortcircuit971/photo-1.jpg

[Agent Smith]

Your problem isn't ignition related. Nor is high CO indicative of "unburned" fuel. As has been pointed out the engine clearly isn't in fuel control.

[shortcircuit971]

While I was there I check all the fuel injectors too since I've never seen the condition of them. I checked the the amount of fuel from each one with the RPM relay jumpered and they were all equal.

7340

I also recorded a video of them because I had a question. When I push down on the air meter plate slowly, all the injectors start with a stream and then equal out to a nice mist. The video is in 720p so you can change the quality to see better. I also tried to have it show both the injector and how far I push the air meter plate in the same frame for the first couple injectors.


http://www.youtube.com/watch?v=5RVpHlhQBxo

Is this usual for them as the pressure builds the further you push the plate down?

After I disconnect the RPM jumper and turn off the fuel pump, if I push down on the air meter plate the injectors no longer spray fuel no matter how far I push it. And there is more resistance to me pushing it down then with the fuel pump running.

Is this normal operation of the system or should the injectors spray when the air meter plate is pushed down even with the fuel pump off? The key is in the ACC position the whole time during all these tests.

[shortcircuit971]

Your problem isn't ignition related. Nor is high CO indicative of "unburned" fuel. As has been pointed out the engine clearly isn't in fuel control.

I rented a fuel pressure test kit from autozone, but it doesn't have the t-connector to connect it to both the fuel distributor and control pressure regulator as it shops in the workshop manual. Is there another way to test the pressures with a single gauge as in the autozone kit?

[DMCTek]

Your plugs look to be good. If you replace them I agree with Ron stick with the stock Bosch plugs.
I was unable to view your injector test video. What you described all seems normal. You should get more fuel the further you push the air metering plate. It is important you get the same amount of fuel from every injector. You should also get no spray out of the injectors with the fuel pump off.

[shortcircuit971]

Your plugs look to be good. If you replace them I agree with Ron stick with the stock Bosch plugs.
I was unable to view your injector test video. What you described all seems normal. You should get more fuel the further you push the air metering plate. It is important you get the same amount of fuel from every injector. You should also get no spray out of the injectors with the fuel pump off.

That's exactly what the car is doing, so everything there seems to be ok. What would be the next thing to test or the next path to follow?

In the morning I'm going to get the car nice and warm and then test the FV duty cycle and the O2 sensor. When checking the O2 sensor voltage, should it be with it connected to the Lambda module, or disconnected?

Oh, I think the video should be fixed, I had it set for private by mistake.

[David T]

It is not possible to see the pattern well enough in the video to see how the injectors squirt. They should "mist" the fuel and not have any jets or streams of fuel shooting out. The plugs look OK but for the work and cost involved it is always better to just replace them. Unless you have a cleaner for them and regap them. Make sure the plugs are all evenly gapped and use a SMALL amount of Never-Seize on the threads. It is important that the injectors all emit the same amount of fuel but is is just as important that the pattern be good. Otherwise you are not vaporizing all of the fuel.
David Teitelbaum

[DMCTek]

That's exactly what the car is doing, so everything there seems to be ok. What would be the next thing to test or the next path to follow?

In the morning I'm going to get the car nice and warm and then test the FV duty cycle and the O2 sensor. When checking the O2 sensor voltage, should it be with it connected to the Lambda module, or disconnected?

Oh, I think the video should be fixed, I had it set for private by mistake.

The video of the fuel spray pattern looks good. Be careful spraying fuel into a glass marked Bud Light!

I would do the FV duty cycle test. You can also test certain O2 failures at the same time. If the duty cycle stays constant at 45 this can point to a bad O2.

O2 sensor can be checked hooked up or disconnected. I usually clip to the spade connector coming through the body near the LR tire.

[Ron]

Based on the picture, do you think I can reuse them for now to continue diagnosis and pass emissions?
Yes


Nor is high CO indicative of "unburned" fuel.
Just an FYI and to expand on "pollutants"- An A-F ratio of 14.7:1 is called stoichiometric, meaning it has exactly enough air to completely burn the fuel. At A-F ratios below stoichiometric high levels of CO and HC are emitted as a result of incomplete combustion of fuel. As the A-F ratio increases below the stoichiometric value, CO and HC emissions decrease, but NOx rise. At ratios slightly higher than stoichiometric (14.7 to ~17.6), CO and HC remain low and NOx emissions remain high. At higher ratios, the CO and HC emissions rise moderately and NOx emissions decrease sharply. Ignition timing affects the formation of HC and NOx. The ratio and timing affect fuel consumption.


Is this usual for them as the pressure builds the further you push the plate down?
...
Is this normal operation of the system or should the injectors spray when the air meter plate is pushed down even with the fuel pump off?
Yep.

Hard to say from a vid...maybe a little "sloppy" at first...doubt they are the problem.
You can get a few sprays with the pump off as you relieve residual system pressure....

Looks OK...


The video of the fuel spray pattern looks good. Be careful spraying fuel into a glass marked Bud Light!

I would do the FV duty cycle test. You can also test certain O2 failures at the same time. If the duty cycle stays constant at 45 this can point to a bad O2.

+1 !!!

You should make sure the engine is fully up to temp (but not 'hot').
After making any adjustments, ALWAYS plug the CO adjustment access hole (each time!), revv the engine and hold for ~15 seconds, and then let it idle for 30 seconds -- THEN take you reading -- Not doing this could cause the symptoms.

[Spittybug]

Rereading your first couple of posts, I can't help but wonder if you still don't have an issue with the vacuum advance solenoid. You said that it worked based on checking it (micro switch on throttle spool kept it off, then allowed it to open), but have you checked to ensure that under normal idle conditions the micro switch is truly being depressed? Perhaps it needs a minor position adjustment to make sure that the lever on the throttle spool is actually engaging it? I ask this because a) your plugs look fine and b) your CO number isn't bad at higher idle. Both of these (I would think) would be affected by a FV or O2 sensor issues. Too much advance at idle would certainly explain these readings. It could also explain the occasional miss at idle.

By all means keep going down the path that everyone else is suggesting, but take 1 minute to check this too. It could save a lot of time and energy.

[shortcircuit971]

Rereading your first couple of posts, I can't help but wonder if you still don't have an issue with the vacuum advance solenoid.

I ask this because a) your plugs look fine and b) your CO number isn't bad at higher idle. Both of these (I would think) would be affected by a FV or O2 sensor issues. Too much advance at idle would certainly explain these readings. It could also explain the occasional miss at idle.

In the first post the original readings show the CO at idle is ok and it's almost double at 2500 RPM. I know I wrote it in kind of a confusing way, so I finally took the time to get an image of the actual test results so it's easier to read. Sorry about the delay.

7342

[Spittybug]

Nope, my bad.... I must be a little dyslexic. Or is that cixelsyd?

[shortcircuit971]

So I didn't get a chance to do any running tests or any warm tests since I haven't had time to put the fuel injectors back in yet. But I did get a chance to check some sensors.

I found that the idle thermister reads 30.12 kilo-ohms while cold and ambient air temp is around 35F. If I'm not mistaken it should be CLOSED below 59F and OPEN above that, so that sensor is bad.

Would that affect the emissions test when I retest because its only an issue at cold idle? All I want for now is to pass emissions, I can fix a cold idle issue when its not close to freezing outside lol.

Also, pin 5 on the Lambda connector is not connected to ground when tested with a multimeter, it's a completely open circuit. The other ground, pin 16, is ok though. I posted the picture below because I'm not sure if the pin layout is exactly the same as the connector layout. In the picture the wires from the Lambda connector are coming out the bottom.

http://i297.photobucket.com/albums/mm216/shortcircuit971/photo2-2.jpg

Could someone confirm that the pic shows the correct pin layout of the Lambda connector?

Where does that ground go to so I can check the connection and repair it?

[Bitsyncmaster]

The thermistor going to the idle ECU is a resistance sensor. It can read from 400 Kohms (real cold) to about 1 Kohm engine hot.

One of those lambda grounds drives the FV ground only. You probably fount that pin. It only gets grounded (connected to the other ground) when plugged into the ECU.

[shortcircuit971]

The thermistor going to the idle ECU is a resistance sensor. It can read from 400 Kohms (real cold) to about 1 Kohm engine hot.

Oh, ok. I thought the thermister was bad, good to know that's ok.


One of those lambda grounds drives the FV ground only. You probably fount that pin. It only gets grounded (connected to the other ground) when plugged into the ECU.

So when testing the connector as I did with it off the Lambda module, I shouldn't be getting a ground to that pin? If that wire goes to the FV ground, could I test that wire by continuity test between the Lambda connector and the FV connector?

[Bitsyncmaster]

So when testing the connector as I did with it off the Lambda module, I shouldn't be getting a ground to that pin? If that wire goes to the FV ground, could I test that wire by continuity test between the Lambda connector and the FV connector?

There are a couple of ground lugs also that need to be tied to the case. Make sure the metal plate the ECU mounts on is grounded.

From memory, the two FV wires go directly to the ECU to FV. You could buzz those to make sure.

[Agent Smith]

..Just an FYI and to expand on "pollutants"-.....

Hey thanks for that little lesson but it's not correct. Close, but no cigar. Feel free to post your emissions credentials and experience though. I'll show you mine if you show me yours.

[Ron]

Hey thanks for that little lesson but it's not correct. Close, but no cigar. Feel free to post your emissions credentials and experience though. I'll show you mine if you show me yours.The "little lesson" was a paraphrase from World Bank Technical Paper ... Vehicular Air Pollution, Pg 60 (http://books.google.com/books?id=XSUS234DhEsC&pg=PA60&dq=high+CO+in+exhaust&hl=en&sa=X&ei=I7bqTtLqBcjqtgf2iswq&ved=0CEMQ6AEwBDgK#v=onepage&q=high%20CO%20in%20exhaust&f=false). If I misinterpreted somehow, please feel free to correct it, or the papers findings. Either would be more useful to the OP than posts with nothing but rude insulting platitudes. Or, especially if your credentials rival theirs, maybe you cold add something the OP (or all of us) could use. I'm quite comfortable with mine, but if you feel the need to flaunt your credentials and experience, perhaps you should edit your profile (http://dmctalk.org/profile.php?do=editprofile) -- If that is not proactive enough for your ego, you'd do better starting your own thread in the open section...although, somehow I feel everyone would be served better if you spent your time contemplating what to to with your cigar.

[Spittybug]

I smell the Monch.

[Agent Smith]

So your creds are you borrowed from a book and still got it wrong? That's it? Lmfao. I don't know whether to be insulted or not.

Ok Sparky, you win. I'll bow out and leave offering emissions advice to the membership in your capable hands. For their sake I hope they take it with a huge grain of salt. Have fun...

[DMCVegas]

While this MAY be a solution, DON'T do it until you have tried the previous post! Idle mixtures don't just spontaneously go out of whack. O2 sensors do however peter out. It is a slippery slide when you start playing with mixture without ruling everything else out.

This absolutely cannot be stressed enough! Don't ever touch the Mixture Screw until you've gone through the entire fuel system first.

Now having said that, it definitely appears as though your fuel mixture IS messed up. Now while that screw doesn't turn by itself at all, there is on way however that you fuel mixture *CAN* suddenly get knocked out of whack. And that would be the O-ring seals inside of the Primary Pressure Regulator.

I can attest first hand to running fuel treatments through my car and achieving failed emissions as well as poor fuel economy when my O-Rings split. If the rings can't hold pressure, they bleed off fuel from the lower chambers of the Fuel Distributor, and thus increase the fuel mixture. In my case like yours I simply replaced the rings, primed the fuel system, and the car fired right up with no problems starting, no passing smog.

It certainly may not be the case here, and you wouldn't know it without a CIS fuel pressure tester, but you won't know until you start looking for the problem.

[Ron]

So your creds are you borrowed from a book and still got it wrong? That's it?Not hardly.
That was from an image, so I typed it out. You said it was wrong (which remains to be seen) so I gave you the source. So, my credentials have nothing to do with it (nor yours). Theirs speak for for themselves. Besides there are a lot of idiots out there "with credentials".


Lmfao So much for my idea on the cigar.


I don't know whether to be insulted or not. How can I reciprocate and remove all doubt?


Ok Sparky,Besides being childish, that particular name would be a better fit in a wiring thread.


...you win. I'll bow out and leave offering emissions advice to the membership in your capable hands. For their sake I hope they take it with a huge grain of salt. Have fun...What were we playing??? Or did you mean the cigar?
I seriously doubt whatever you were babbling about being wrong (or missing or ???) would have helped the OP's situation, or whether anyone would appreciate the baggage that obviously comes with it.

As for having fun, isn't that what we were doing while he works on checking all of his settings/specs and the O2 sensor?

Hey, you can take the sour grapes along with all of your toys... CYA

[Ron]

This absolutely cannot be stressed enough! Don't ever touch the Mixture Screw until you've gone through the entire fuel system first.
+1!
When the engine runs well enough to do all the tests, leave it alone until last.
If you change ANYTHING later on, check the CO when you are done.

[shortcircuit971]

Now having said that, it definitely appears as though your fuel mixture IS messed up. Now while that screw doesn't turn by itself at all, there is on way however that you fuel mixture *CAN* suddenly get knocked out of whack. And that would be the O-ring seals inside of the Primary Pressure Regulator.

It certainly may not be the case here, and you wouldn't know it without a CIS fuel pressure tester, but you won't know until you start looking for the problem.

I did just ran a can of BG44K through the fuel system, so you may have got it figured out. I rented a fuel pressure tester from autozone but it doesn't come with the right adapters for CIS testing. I'm more electrically inclined, but I want to learn how to fix the fuel system myself instead of taking it to a shop.

Where would I get the right pressure tester? Preferable one I can rent since all my money is in books and school.

Where do I connect the pressure lines to test for bad o-rings?

If it is the o-rings, could I just turn the air fuel mixture screw down enough (leaner) next to the test center to pass and then turn it back up and replace the o-rings come spring, or would it mess up the idle test or other things like HC, CO, CO2, or NOx?

[shortcircuit971]

Also, on top of my previous post, I went digging through my files and found the passed emissions test from last year exactly 12 months ago. Here is last years emissions sheet. Nothing has been done to the car since except for smoke testing for vacuum leaks using an automotive smoke machine and then fixing the leak found at the rubber boot of the electrical connector on the vacuum solenoid that goes to the distributor. As I said in the previous post too, BG44k was run through 1 full tank before filled again for the test.

7358

For an easy reference between the two, here is this years failed test.

7359

The CO2 seems about the same between this year and last, maybe the slightest bit lower when it failed then when it passed. Based on having higher HC and CO at 2500RPM than last year while having about the same HC and CO at idle for both years, would you say it is most likely a particular o-ring?

If it is an o-ring, or just based on the just the two emissions results, do you think I could get away with my previous idea of turning the air/fuel to a little lean to pass the test until I can repair the o-rings in the spring?

[Bitsyncmaster]

Based on the two tests, I would say your not getting vacuum advance. Maybe your distributor advance unit has failed. Do you have a timing light?

You can test if it works by pulling the idle motor connector off (when the engine is idling), then pull the idle switch off and RPMs should go up about 500 RPM.

[shortcircuit971]

So today I was able to take it out for a test drive to get it good and warm. The main reason for the test drive was to check the Lambda system. I had a duty cycle meter connected to the diagnostic port pins for the frequency valve. I did find out that the full throttle micro switch doesn't work. The switch works, but there is a break in the wire somewhere on its way to the Lambda computer, so it doesn't set the duty cycle to a rich mixture at full throttle. Here are the duty cycle results.

Cold engine = 50-70% (at idle and cruising)
Warm engine = 28-45% (at idle)
Warm engine = 55-70% (while cruising, higher % under load, but normally in the 60's range)

The only thing I noticed was if I cruise at any speed and then take my foot completely off the peddle, the frequency valve drops to 0% duty cycle while the engine is slowing the car down. Once it gets into idle RPM, the frequency valve jumps back to the correct duty cycle. Is this normal operation? Could this be what's affecting the emissions test? Is there a diode somewhere in the idle circuit that could go bad and backfeed power into the Lambda system?

[Bitsyncmaster]

Cold engine the FV should be a solid 50% or 60% if the temp is very cold.

Your warm idle of 28 to 45 % looks good.

It should also hold those same values when cruising but I must admit I have not run a meter on it when on the road. So it seems like your cruising is caused by the FD going a little lean and then the lambda is bringing it back to normal. If it goes to 0% on deceleration then something is driving it to rich.

I would think since the lambda is still in control (it can work from 15% to 90%) your mixture should not have caused you to fail the emissions test.

One thought is the lambda is an average of all the cylinders. So if one cylinder is very rich, it would lean out the others to get the average 14.7 AFR. Have you pulled the injectors and looked at the spray pattern on all six?

[shortcircuit971]

One thought is the lambda is an average of all the cylinders. So if one cylinder is very rich, it would lean out the others to get the average 14.7 AFR. Have you pulled the injectors and looked at the spray pattern on all six?

Yup, a couple pages back on this thread I posted a video of all the injectors as well as a picture of the spark plugs. All seem to be spraying and sparking the same as the other lol.

Note: I figured out the full throttle micro-switch. It was plugged into the auto trans connector. The PO labeled them wrong and the wires were too dirty for me to really see the color of the green wire.

[Bitsyncmaster]

Yup, a couple pages back on this thread I posted a video of all the injectors as well as a picture of the spark plugs. All seem to be spraying and sparking the same as the other lol.

Note: I figured out the full throttle micro-switch. It was plugged into the auto trans connector. The PO labeled them wrong and the wires were too dirty for me to really see the color of the green wire.

When the WOT switch is activated your FV should hold a solid 60%. That is why your cruse should be running 30 to 40% so the 60% at WOT would give you a rich mixture. If your already cruising at 60% or more than WOT will not do anything.

[shortcircuit971]

When the WOT switch is activated your FV should hold a solid 60%. That is why your cruse should be running 30 to 40% so the 60% at WOT would give you a rich mixture. If your already cruising at 60% or more than WOT will not do anything.

So what would be causing the duty cycle to go higher and the fuel to go richer when the RPMs are higher?

Tomorrow I'm going to test the timing to see if that's the problem. Where in the workshop manual will I find the proper ignition timing test procedures? Or if anyone knows of a better online site/thread for testing ignition timing? Thanks.

[Ron]

where in the workshop manual will i find the proper ignition timing test procedures? m:01:01-04

[shortcircuit971]

m:01:01-04

Perfect, thank you.

[shortcircuit971]

So up until now I did not realize I had the duty cycle meter leads reversed. So 40% meant 60% and so forth. Ignore all my previous readings, here are the new and updated readings as of today's nice long drive:

With a warm engine, while the O2 sensor is still warming up the last little bit, it sits at a steady 50% +/- 1%. After the O2 sensor heats up, while cruising it fluctuates between 32-44%. While at idle, the duty cycle fluctuates between 66-79%. While decelerating while in gear, the duty cycle goes FULL RICH (100%). I previously though it was going lean since it read 0% but that was when the leads were switched. When at full throttle it sticks to 60% until I let off.

Why does it go out of range at idle and give a richer mixture? It passed idle emissions, just not at 2500RPM.

I also tested the timing. At idle its at about 12-13 degrees. With the vacuum advance disconnected at 2500RPM it was close to the edge of the timing plate, near or above 20 degrees, hard to tell. With the vacuum advance reconnected it would jump off the chart at anything above idle. Otherwise it sat at 13 degrees.

Is this normal timing advance operation? What would be my next step to test?

[Bitsyncmaster]

So your idle is to lean and the lambda is correcting. A lean idle could be caused by vacuum leak. But I would guess you have all that checked.

I would make the adjustment for 30 to 40% at idle and see what that does to the cruse RPM.

Yes, use that WOT switch to check your meter. It holds a pretty accurate 60% so if your reading 40% the meter is not connected correctly. You will also get that reversal if your meter (-) is connected to +12 volts. There is +12 volts on the test connector.

[shortcircuit971]

So I went for a retest today since I had some time and I wanted to see if I made any progress. It failed in an odd way. When I got home I realized I left the vacuum line that goes from the thermal vacuum control valve to the vacuum advance solenoid unplugged from the solenoid by accident, so there was a vacuum leak for today's test. The only other changes I made from the test 2 weeks ago are as follows:

Swapped back to dirty DMC-H NOS air filter from the new K&N I bought from specialTauto (I figured it passed with the old one last year, it can pass with it this year. I want to eliminate any changes since it passed last year). Found the vacuum delay valve was reversed so I switch it back. And lastly I turned the air/fuel to lean a tiny bit so that at higher RPM's the duty cycle was between 35-45%. At idle it still goes up really high in the 80s-90s.

7474

Could I disconnect that same vacuum hose again and plug it to pass? It passed 2500RPM with no distributor vacuum advance the way it is right now, and at idle the vacuum line is shut off at the solenoid, so plugging that vacuum line should at least get me to pass?

Lastly, could I just tune the car to 50% when its above idle, and then disconnect the O2 sensor and have it run in open loop during the test?

[Bitsyncmaster]

The advance would give you a more compleat burn of the fuel.

[shortcircuit971]

The advance would give you a more compleat burn of the fuel.

Then why did HC, CO, and CO2 pass at 2500RPM with the vacuum advance line disconnected on the test I did today? I hope that didn't come off mean, I'm just trying to figure out what causes what since by fixing one thing another thing goes wrong.

How is the vacuum advance on the distributor tested with a vacuum pump? Does it go off the scale of timing marks? When holding a steady 2500 RPM, isn't the advance from vacuum negligible since manifold pressure is equal to ambient air pressure while the throttle plates are opened, which means I could plug the vacuum advance for emissions testing and it shouldn't matter?

[Bitsyncmaster]

Then why did HC, CO, and CO2 pass at 2500RPM with the vacuum advance line disconnected on the test I did today? I hope that didn't come off mean, I'm just trying to figure out what causes what since by fixing one thing another thing goes wrong.

How is the vacuum advance on the distributor tested with a vacuum pump? Does it go off the scale of timing marks? When holding a steady 2500 RPM, isn't the advance from vacuum negligible since manifold pressure is equal to ambient air pressure while the throttle plates are opened, which means I could plug the vacuum advance for emissions testing and it shouldn't matter?

Good question. My guess would be the lambda adjusted the mixture to go lean.

With a constant throttle you still get a good manifold vacuum. So it should be close to maximum vacuum advance at 2500 RPM. It's only when you open or punch the throttle that the vacuum drops.

[Ron]

How is the vacuum advance on the distributor tested with a vacuum pump? Does it go off the scale of timing marks? Yes..you would need to do it with one that has a gauge on it and use the chart at the end of the same section in the manual. It will go off scale at the last test but not enough that you can't tell if there is a problem...

As you said, not trying to be mean, but I think you need to quit swapping parts and adjusting things...start all over and strictly follow the procedures in the manual. If for any reason you change anything else, start ALL over again. You can't skip a step (ie precise pressure check, fuel volume check, etc) just because you don't have the tools -- Values afterwords are all but meaningless. Something as simple as using injector cleaner can change everything (one injector may clean up, another may snag something turned loose upstream, or, quite often, it contaminates the O2 sensor....). Like Dave S said, you'll probably wind up frustrated.

Earlier I said the injectors looked a little "sloppy" at first. Am I the only one not liking the way some stream at first?
That being near idle and agreeing with Bitsy's thoughts on the averaging, I really think they need to be revisited and measured....

[shortcircuit971]

Yes..you would need to do it with one that has a gauge on it and use the chart at the end of the same section in the manual. It will go off scale at the last test but not enough that you can't tell if there is a problem...

As you said, not trying to be mean, but I think you need to quit swapping parts and adjusting things...start all over and strictly follow the procedures in the manual. If for any reason you change anything else, start ALL over again. You can't skip a step (ie precise pressure check, fuel volume check, etc) just because you don't have the tools -- Values afterwords are all but meaningless. Something as simple as using injector cleaner can change everything (one injector may clean up, another may snag something turned loose upstream, or, quite often, it contaminates the O2 sensor....). Like Dave S said, you'll probably wind up frustrated.

Earlier I said the injectors looked a little "sloppy" at first. Am I the only one not liking the way some stream at first?
That being near idle and agreeing with Bitsy's thoughts on the averaging, I really think they need to be revisited and measured....

No worries, I understand. I was making a learning experience out of it for myself and wanted to get familiar with all the components. I didn't replace or swap any components, just tested this and that. The only thing I adjusted was the air/fuel about a 5-10 degree turn to the lean side while monitoring the FV duty cycle. I had to adjust the air/fuel before a couple years ago so it seems like it settled in.

Here's some good news, IT PASSED. This is what I had to do to get it to pass. All I did was disconnect the vacuum line between the vacuum solenoid and the distributors vacuum advance unit. This caused there to be no vacuum advance whatsoever while the engine was running, and a vacuum leak only when out of idle (that is when the idle microswitch is disengaged and the vacuum solenoid passes vacuum to the other port). Here are the emissions results.

7480

[Bitsyncmaster]

Glad your back driving for another year. Does your engine really idle at 1181 RPM?

[Ron]

... I didn't replace or swap any components, just tested this and that.
...
Here's some good news, IT PASSED.
Oh OK...I misinterpreted about putting the old air filter and all back on...

Way to go! hehe...a man after my own heart...now that you tweaked it for the emission sticker, you gotta do for the specs! It's all fresh in your head now and a year will be up before you know it...:deviltail:

[shortcircuit971]

Glad your back driving for another year. Does your engine really idle at 1181 RPM?

Thank you. No it doesn't. For all the other tests it was 775 +/- 25rpm, and when I pulled into and out of the emissions center it was 775. I think the guy had his big fat foot wedged against the accelerator. It was still within their testing limits so I didn't care haha.


Oh OK...I misinterpreted about putting the old air filter and all back on...

You're right, I did put the old air filter back on. But it had the old air filter on last year when it passed. The K&N filter was an upgrade mid-year, so I thought putting in the old filter would be putting the car back to the way it was when it passed last year.


Way to go! hehe...a man after my own heart...now that you tweaked it for the emission sticker, you gotta do for the specs! It's all fresh in your head now and a year will be up before you know it...:deviltail:

Thanks, and don't remind me haha. I'm hoping they give up on emissions again where I live. I had heard that it was a mistake that they brought it back, but it's only just a rumor.