California 87 GN, 160K mile , CANT PASS!!!

[6=8]

I am having troubles! While I am not coming up as a gross polluter, I have tested 2 times and cannot pass the 15 MPH test, even after fixing some exhaust leaks and installing a new CAT.

Here are my numbers on the last test:

15mph: HC: 129 MAX 110, CO 0.14 Max 0.71, NO 73 MAX 772
25mph: HC: 85 MAX 85, CO .0.14 Max 0.59, NO 36 MAX 711

Barely passed HC’s at 25 MPH at 85 ppm, Failed the 15 MPH at 129 ppm

Ive done the oil change, sparkplugs, wires. Car runs well!

I am running blue top injectors, adj Fuel Pressure reg at 43 PSI, and a Walbro pump, ramchargers chip to match the injectors.

I have passed with this combo 2 years ago.. No real changes except for the pump and regulator.

I have read discussions about turning the pressure down to lean it out, but other say this reduces atomization and makes matters worse.

Please! Any help would be greatly appreciated! I'm not opposed to putting the stock injectors back on and getting a new chip, if that seems like a sure fire way to passing!

Thanks,
Tim

 

[gofstbuick]

I need the rest of the readings and email or PM your license plate# to me (then I can see all the readings for myself).

 

[Harry Mash]

Gofstbuick, after you work on this problem, please note your findings on this site so we may better understand the interplay between the measurements. Thank you.
Harry

 

[gofstbuick]

Harry,
There is a relationship between the 5 gases (hc,co,nox,O2 and CO2) that yields 14.7:1 a/f ratio. For those that live in CA it is sometimes easier for me to look at all the test (since I can) and sometimes people don't post all the readings (thinking that O2 and CO2 don't matter). Lots of problems occur when aftermarket PCV valves and EGR valves are used. The aftermarket version of those part rarely flow like a factory part and for that matter were never put through the Federal Test Procedure test. A specific percentage of a vehicle line must pass a FTP test for the line to be federally emissions certified. During the test, the manufacturer brings the vehicle to the test facility and the test is conducted. You wouldn't think that a manufacturer would use after market parts for that test? That is why delco pvc valves and EGR vavles are critical. Especially for those haveing to go through I/M 240 or some derivitive of I/M240. CA uses steady state on the dyno, so emissions are easier to control than those test in which emissions are measured at different speeds and dyno loads.

 

[Harry Mash]

Gofstbuick-thank you for the response. I am still interested in this specific case and what may have caused the the high hc reading.
Regards,
Harry

 

[gofstbuick]

Originally posted by Harry Mash
Gofstbuick-thank you for the response. I am still interested in this specific case and what may have caused the the high hc reading.
Regards,
Harry

Will let you know after the weekend, he said he will let me know some results this weekend.

 

[ChrisChow]

Turn the fuel pressure down. Lean it out and try again. You are far from being too lean as indicated by the Nox.
Go to a station and let them know you want to check it out before running the official test.

If you run too lean the Nox goes up.

 

[gofstbuick]

Originally posted by ChrisChow
If you run too lean the Nox goes up.

Part of that statement is true. NOx will rise when too lean, but beyond a certain point, NOx will fall really low if there is not enough fuel to fire the mixture. At that point you are in or bordering on lean misfire.

 

[6=8]

Sorry guys... Have not had it fired up for a while. Got a 3-day weekend coming, so I should have some time to get some readings.

 

[6=8]

BLMs are in...

OK... Back from business trip and I have time to play some more...

My BL readings at 25 MPH are from 104 leveling off and hanging around 92.
At 15 MPH, leveling off to 97

If my BLM research is correct, 90 is as low as it goes, right?

Also, I never drive at these speeds! Could it be my other trips to the smog station were premature? What I mean is, the ECM has not calibrated for these speeds, so it never has time to adjust itself before the check?

My HCs are not that far off. Now that the weather has hit triple digits around here, maybe I can heat this thing up and spend another 20 bucks as hope for the best?

Also, Even though the o2 is 4 months old, I might swap in another just to see.

My MAF is original, so maybe it is getting flat. I notice at these speeds, the AF reating is 05 - 08. At 775- 800 rpm idle, it reads 05!!! Maybe its ok for normal driving, but at these speeds, tricks the ECM enough to run outside the emissions range...

Im just reaching at this point, but I've checked it all out - Vacuum lines, regulator, CAT, headers... this thing is pretty tight for pushing 170K miles.

Let me know what you think!!! I miss my car!

 

[gofstbuick]

Actually, low blm is rich and the ECM is trying to subtract fuel

 

[6=8]

Update - Injector Timing/Cam Sensor Check

I have an update...

So, I got to thinking.. Why Am I blowing high HC's, and the computer is seeing some of this, and pulling fuel out by lowering the BL? I purchased the CAM SENSOR Adjust tool a while back and thought I would give it a check last night.

I found it was OK... Minor adjustment, if any.

However, in cranking the engine by hand to move the timing mark where I could put the sticker on, I felt a considerable amount of end play. In other words, when I reverse my crank rotation, it feels loose then gets tight. To measure this, I cranked the engine back to TDC, and revesed diretion to get a feel for how much play I was dealing with. 4 degrees!?!? Is this normal?

After giving this new twist more thought, I'm thinking my timing chain has a large amount of slack. It is an aftermarket roller with 10K miles. Remember, the engine is high milage, compression is ok last time I checked.

So, could this 4 degree "Play" be affecting the injector timing enough to cause a rich condition? I'm thinking I lost the chain tensioner.

Let me know what you think... Anyone else notice this much rotational play when cranking an engine over by hand?

 

[gofstbuick]

I may be wrong, but I'm going to say no. From experience, my tensioner was warn 2/3rds of the way. Used a tensioner with a DR. The emissions still passed very clean. Some others may chime in.

 

[6=8]

Next Step?

OK... I'll assume the "Play" has nothing to do with this. The car runs fine anyway... No driveability problems.

What do you recommend my next step to be?

I've rolled my car back to a setup that worked 2 years ago. Stock Pressure regulator and a Previous chip: My BLM's still hover around 92 - 98 at 15 and 25 MPH... so the ECM sees it being rich and is trying to take fuel out, but it is not taking enough out to pass.

I plan on replacing the O2 sensor tonight to see what changes that makes. I'm doubtful this will have any affect. The one in there is only 5 months old (1 of those months- Just sitting in the garage!)

Next item to look into swapping is the MAF (Since it has never been replaced by me)

Any other suggestions? On cars that are high on HC's, what has typically fixed the situation? I'm not against looking into an emissions chip that will run my car lean at these speeds. Should I just go for something like that? I need to get this car back on the road!

Thanks!

 

[gofstbuick]

who's chip now? After changing chips, did you give it some time to learn?

 

[6=8]

Hey there!

Its a Ramchargers 93 chip. Had a Ramchargers 91 in there during the emissions test. Both running similar numbers.

At 15 and 25 MPH driving, the BL numbers settle in at 98-95 (15) and 97-92 (25 MPH) Drove at these speeds for about 10-15 constantly... Slight inclines, back down, and level driving mixing it up.

I've new information: I see a fair amount of OIL on the intake side of the turbo (Looking in with the MAF pipe removed) Based on the amount I see buddled in the "Bell", I am suspecting the turbo bearing/Seal is allowing oil into the intake. There is more here than I would expect, even with the breather tube (Emissions Mandated) installed.

How does this affect emissions? Would too much oil being burned increase the HC results?

 

[gofstbuick]

Oil will coat the O2 sensor and affect response. Those bl numbers are really low. Can you get the BL numbers to rise?

 

[6=8]

I'll try.

I put the factory Regulator back on... I will have to put the Adjustable one on there and turn the PSI down more. It was at 40 PSI line off before I swapped it out.

I'll just start cranking it down and see what happens to the numbers.

What should the AF numbers be at 15 and 25?

 

[gofstbuick]

During the test, your engine will be at a steady state and a fixed load. This should give the ECM time to adjust and BL should be near 128, give or take 10

 

[6=8]

I Passed!!!

3rd times a charm. Actually, I learned quite a bit! Thanks for the help in letting me know what these numbers mean. My fuel pressure was not being properly regulated at lower RPMs

Recap: My GN was failing 15 and right at the limit for 25 MPH tests due to high HCs. Replacing the CAT and 02 sensor did not make a difference in HC numbers.

My testing using a scanmaster and driving at these speeds revealed LOW BLM readings 90-98, specifically at these speeds, indicating the ECM realized there was too much fuel and was taking fuel out, but not enough to pass. (128 is nominal)

My Fuel pressure was set at 43 PSI, line off. Vacuum lines checked, and were OK.

I decided to drop the fuel pressure to 38 PSI, reset the computer, and take another drive. The numbers were almost the same.

I put the stock regulator back on, and the numbers were the same.

Decided to drop the fuel pressure again and re-installed the adjustable one.... But found I could not get lower than 38. Also, at this time, I realized that when I put the vacuum line back on the regulator, the fuel pressure was the same as with the line off??? It did not drop.

I clamped the rubber feed line (Near the tank) with a clamp to reduce the flow and PSI to see if I could lower it. Sure enough this worked, but resulted in a massive fuel leak above the tank!

So, I have either a clogged return line, or at the very least, I am overloading it with that Walbro 307 pump. I inspected the return line from back to front, it was not damaged (But still could be clogged. It is only 1/4 inch dia.)

I swapped out the pump for a Stock volume one from NAPA, replaced all the rubber lines and hose clamps above the tank. After the pump change, when I put the vacuum line back on, I noted the pressure was able to drop from 38 to 20. With the fuel pressure under control, driving around resulted in BLMs of 112 - 118. I attribute this to a couple of factors, such as a "Well Worn Engine" with turbo bearings on the way out (leaking small amounts of oil into the mix.)

These numbers resulted in a pass:
15 MPH HC passed at 109 (110 allowed), was failing at 146!
25 MPH HC passed at 70 (85 allowed), was failing at 86. 1 test prior was right at 85.

So, I hope this little write up helps others get to the bottom of this kind of prob. Check that the LINE ON pressure drops from the initial line off setting. Mine dropped from a setting of 38 to 22-25PSI with the lower volume pump. If your pressure is not dropping, check the regulator, return line, Vacuum line, and see if your pump is overloading the return line!

I think the return line is the real problem, and the low volume pump was a band-aid fix.

I'll post the PASS and FAILED test results...