Idle Emissions FAIL
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Registered User
Joined: Mar 2011
Posts: 52
From: Vancouver, WA
Idle Emissions FAIL (Updated 7/22/11)
So my 95 LT1 failed WA state emissions today due to high hydrocarbon levels at idle (HC PPM 645. Passing is 220). What are the first things I should look in to?
It's not throwing any codes. It has 208,000 miles overall (much less on the replacement motor). I have not changed the stock exhaust, cat, or muffler, etc. The carbon canister lines under the fender well are tight/good. It has had a full tune-up, including replacement Opti, plugs, wires, and other parts such as fuel filter and PCV, EVAP purge control solenoid, coil, and ICM, as well as a few other things in recent months.
I do have the capability to put it on a Scanmaster program via my laptop and cable, which I'll do but I'm pretty 'new' when investigating these things.
Thoughts?
It's not throwing any codes. It has 208,000 miles overall (much less on the replacement motor). I have not changed the stock exhaust, cat, or muffler, etc. The carbon canister lines under the fender well are tight/good. It has had a full tune-up, including replacement Opti, plugs, wires, and other parts such as fuel filter and PCV, EVAP purge control solenoid, coil, and ICM, as well as a few other things in recent months.
I do have the capability to put it on a Scanmaster program via my laptop and cable, which I'll do but I'm pretty 'new' when investigating these things.
Thoughts?
Last edited by Misfit74; Jul 22, 2011 at 03:37 PM. Reason: update title
Registered User
Joined: Jul 2002
Posts: 1,942
From: Kissimmee, Fl, USA
Re: Idle Emissions FAIL
So my 95 LT1 failed WA state emissions today due to high hydrocarbon levels at idle (HC PPM 645. Passing is 220). What are the first things I should look in to?
It's not throwing any codes. It has 208,000 miles overall (much less on the replacement motor). I have not changed the stock exhaust, cat, or muffler, etc. The carbon canister lines under the fender well are tight/good. It has had a full tune-up, including replacement Opti, plugs, wires, and other parts such as fuel filter and PCV, EVAP purge control solenoid, coil, and ICM, as well as a few other things in recent months.
I do have the capability to put it on a Scanmaster program via my laptop and cable, which I'll do but I'm pretty 'new' when investigating these things.
Thoughts?
It's not throwing any codes. It has 208,000 miles overall (much less on the replacement motor). I have not changed the stock exhaust, cat, or muffler, etc. The carbon canister lines under the fender well are tight/good. It has had a full tune-up, including replacement Opti, plugs, wires, and other parts such as fuel filter and PCV, EVAP purge control solenoid, coil, and ICM, as well as a few other things in recent months.
I do have the capability to put it on a Scanmaster program via my laptop and cable, which I'll do but I'm pretty 'new' when investigating these things.
Thoughts?
Thread Starter
Registered User
Joined: Mar 2011
Posts: 52
From: Vancouver, WA
Re: Idle Emissions FAIL
CATEGORIES (5):
HC (PPM) | CO (%) | CO+CO2 (%) | O2 (%)| RPM
Cruise Limits -
> 150 | 1 | 6 | N/A | N/A
Cruise Emissions -
> 131 | 0.13 | 15.13 | 0.62 | N/A
Cruise Results:
> PASS | PASS | N/A | N/A | N/A
_______________________________
Idle Limits -
> 220 | 1.2 | 6 | N/A | N/A | N/A
Idle Emissions -
> 645 | 0.33 | 14.93 | 0.93 | 610
Idle Results:
> FAIL | PASS | N/A | N/A | N/A
Administrator
Joined: Nov 1998
Posts: 71,094
From: Hell was full so they sent me to NJ
Re: Idle Emissions FAIL
High HC and CO (with low NOx, which they do not appear to test for) would indicate a rich mixture. All three being high would make the condtion of the cat suspect. But high HC with low CO would be pointing to something like leaking injector(s), leaking fuel pressure regulator.
Thread Starter
Registered User
Joined: Mar 2011
Posts: 52
From: Vancouver, WA
Re: Idle Emissions FAIL
No fuel in the fuel pressure reg. vacuum line.
I did find one injector's connector a little loose (far passenger rear), though I'm not sure it was loose enough to not fire properly. I didn't notice symptoms in how the car ran - but will secure that, as well.
Going to continue to inspect suggested items from above replies, then run some scanning.
FPR doesn't appear to be leaking. Not to start throwing parts at it, but having never replaced it since I've owned the car ('07), should I think about replacing it anyway? Delco makes only a service kit w/ seals, etc. Otherwise Airtex (Air-techs?) is the other available brand locally (so far).
I did find one injector's connector a little loose (far passenger rear), though I'm not sure it was loose enough to not fire properly. I didn't notice symptoms in how the car ran - but will secure that, as well.
Going to continue to inspect suggested items from above replies, then run some scanning.
FPR doesn't appear to be leaking. Not to start throwing parts at it, but having never replaced it since I've owned the car ('07), should I think about replacing it anyway? Delco makes only a service kit w/ seals, etc. Otherwise Airtex (Air-techs?) is the other available brand locally (so far).
Last edited by Misfit74; Jul 3, 2011 at 01:25 PM.
Administrator
Joined: Nov 1998
Posts: 71,094
From: Hell was full so they sent me to NJ
Re: Idle Emissions FAIL
A single-cylinder misfire would also dump fuel into the exhaust. And that lowers CO, because there is no combustion on that cylinder.
An injector that wasn't firing would not cause fuel to be in the exhaust, just the opposite. And if the injector wasn't firing, you would have a code.
An injector that wasn't firing would not cause fuel to be in the exhaust, just the opposite. And if the injector wasn't firing, you would have a code.
Thread Starter
Registered User
Joined: Mar 2011
Posts: 52
From: Vancouver, WA
Re: Idle Emissions FAIL
A single-cylinder misfire would also dump fuel into the exhaust. And that lowers CO, because there is no combustion on that cylinder.
An injector that wasn't firing would not cause fuel to be in the exhaust, just the opposite. And if the injector wasn't firing, you would have a code.
An injector that wasn't firing would not cause fuel to be in the exhaust, just the opposite. And if the injector wasn't firing, you would have a code.
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Joined: Oct 2006
Posts: 2,728
From: Post Falls, Idaho
Re: Idle Emissions FAIL
My Camaro failed and someone recommended adding 2 bottles of heat and it passed next time with no problem. I was also told to run the car as little as posssible right before and do it on a cooler day when there are no lines. I also did a few WOT just before on the freeway. This won't work for every problem of course.
Thread Starter
Registered User
Joined: Mar 2011
Posts: 52
From: Vancouver, WA
Re: Idle Emissions FAIL
I pulled the intake plastic and checked the gasket behind the IAC on the intake; checked for any vacuum leaks with any surrounding lines/connections.
Then, I remembered that the mechanic who first worked on the car back in '07 told me he adjusted the idle 'up' to account for the car's poor performance (which later was found to be the Opti in full). I have to believe he used the stop screw. No tuning was done (no tuning has been done, Dyno-wise).
We backed off the stop screw from two threads showing to one thread showing. This didn't immediately foster a change. But, then I reset the IAC position using the gas-pedal trick. Idle went down significantly (approx as much as 200 RPMs I would guess) in closed loop. I'm crossing my fingers here, as I have some confusion as to the car's ability to 'learn' against the involved components. The MAP sensor is good.
No DTCs duing extensive logging w/ cable/laptop/datamaster software.
Also, the MAF is fairly dirty. Next thing is to clean it really good with some MAF/Electrical cleaner and some Q-tips. I've been avoiding this because I know they're sensitive and easily damaged - and the part is a fortune. But, that is next.
I'm tempted to take it through emissions again right now, but think I'll wait until after the weekend and the MAF cleaning - and some feedback about this so far. Thanks again.
Then, I remembered that the mechanic who first worked on the car back in '07 told me he adjusted the idle 'up' to account for the car's poor performance (which later was found to be the Opti in full). I have to believe he used the stop screw. No tuning was done (no tuning has been done, Dyno-wise).
We backed off the stop screw from two threads showing to one thread showing. This didn't immediately foster a change. But, then I reset the IAC position using the gas-pedal trick. Idle went down significantly (approx as much as 200 RPMs I would guess) in closed loop. I'm crossing my fingers here, as I have some confusion as to the car's ability to 'learn' against the involved components. The MAP sensor is good.
No DTCs duing extensive logging w/ cable/laptop/datamaster software.
Also, the MAF is fairly dirty. Next thing is to clean it really good with some MAF/Electrical cleaner and some Q-tips. I've been avoiding this because I know they're sensitive and easily damaged - and the part is a fortune. But, that is next.
I'm tempted to take it through emissions again right now, but think I'll wait until after the weekend and the MAF cleaning - and some feedback about this so far. Thanks again.
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Joined: Sep 2010
Posts: 131
From: Tennessee
Re: Idle Emissions FAIL
May be irrelevant, buy my truck was doing the same thing. Just an old tbi truck. It had a vacuum leak which wasn't letting the egr work, and also no code indicating (may be different on these cars, I don't know). I think i was somewhere around 500 on the hc n it dropped down to about 150 after I found the leak.
Thread Starter
Registered User
Joined: Mar 2011
Posts: 52
From: Vancouver, WA
Re: Idle Emissions FAIL (updated 7-12)
Test #2 = Failed again.
After:
1. checking all vacuum lines, fuel pressure regulator, and intake
2. cleaning MAF sensor and housing
3. making sure the stop-screw for throttle no longer a factor at all
4. adding 2+ bottles of HEET and running a lot, many WOTs, and car hot
Note: the idle HCs did drop from 645 to 421, though. Unfortunately 220 is passing. Here is the full test-record (WA state): http://emissiontestwa.com/e/TestReco...203:15:34%20PM
Now, I'm thinking of having it tuned at a local performance shop. It must still be getting too much fuel at idle. It has no codes thrown. No parts that I can tell are 'bad'. According to the scan that injuneerZZ read, the car was getting about 13% too much fuel at idle.
More feedback always welcome!
After:
1. checking all vacuum lines, fuel pressure regulator, and intake
2. cleaning MAF sensor and housing
3. making sure the stop-screw for throttle no longer a factor at all
4. adding 2+ bottles of HEET and running a lot, many WOTs, and car hot
Note: the idle HCs did drop from 645 to 421, though. Unfortunately 220 is passing. Here is the full test-record (WA state): http://emissiontestwa.com/e/TestReco...203:15:34%20PM
Now, I'm thinking of having it tuned at a local performance shop. It must still be getting too much fuel at idle. It has no codes thrown. No parts that I can tell are 'bad'. According to the scan that injuneerZZ read, the car was getting about 13% too much fuel at idle.
More feedback always welcome!
Administrator
Joined: Nov 1998
Posts: 71,094
From: Hell was full so they sent me to NJ
Re: Idle Emissions FAIL
You need to re-read what I told you. The PCM is adding 13% extra fuel at idle, due to elevated long term fuel corrections. If you have a "false lean" condition, that means the PCM is adding fuel the engine doesn't need, and its running rich. Getting a tune is not the way solve the problem. You have to figure out why its adding the extra fuel, and whether that is the cause of the rich condition.
If your tune had the wrong injector size, or the MAF sensor was not accurate, or you have a vacuum leak, it would produce a "true" lean condtion, where the PCM has to add 13% to the fuel calculation to fuel the engine correctly. That wouldn't produce a rich condition, that would correct a lean condition.
The difference is whether the PCM is getting good data from the O2 sensors, or bad data. I mentioned misfires and exhaust leaks before the O2 sensors, misadjusted valves, and faulty O2 sensors and/or wires as possible causes. Have you checked those possibilities out?
If your tune had the wrong injector size, or the MAF sensor was not accurate, or you have a vacuum leak, it would produce a "true" lean condtion, where the PCM has to add 13% to the fuel calculation to fuel the engine correctly. That wouldn't produce a rich condition, that would correct a lean condition.
The difference is whether the PCM is getting good data from the O2 sensors, or bad data. I mentioned misfires and exhaust leaks before the O2 sensors, misadjusted valves, and faulty O2 sensors and/or wires as possible causes. Have you checked those possibilities out?
Thread Starter
Registered User
Joined: Mar 2011
Posts: 52
From: Vancouver, WA
Re: Idle Emissions FAIL
You need to re-read what I told you. The PCM is adding 13% extra fuel at idle, due to elevated long term fuel corrections. If you have a "false lean" condition, that means the PCM is adding fuel the engine doesn't need, and its running rich. Getting a tune is not the way solve the problem. You have to figure out why its adding the extra fuel, and whether that is the cause of the rich condition.
If your tune had the wrong injector size, or the MAF sensor was not accurate, or you have a vacuum leak, it would produce a "true" lean condtion, where the PCM has to add 13% to the fuel calculation to fuel the engine correctly. That wouldn't produce a rich condition, that would correct a lean condition.
The difference is whether the PCM is getting good data from the O2 sensors, or bad data. I mentioned misfires and exhaust leaks before the O2 sensors, misadjusted valves, and faulty O2 sensors and/or wires as possible causes. Have you checked those possibilities out?
If your tune had the wrong injector size, or the MAF sensor was not accurate, or you have a vacuum leak, it would produce a "true" lean condtion, where the PCM has to add 13% to the fuel calculation to fuel the engine correctly. That wouldn't produce a rich condition, that would correct a lean condition.
The difference is whether the PCM is getting good data from the O2 sensors, or bad data. I mentioned misfires and exhaust leaks before the O2 sensors, misadjusted valves, and faulty O2 sensors and/or wires as possible causes. Have you checked those possibilities out?
The valve thing I'm not sure what to make of - getting over my head. I can have the exhaust checked for leaks easily (a guy right up the street I know - that's all he does). I'll start w/ exhaust and then go to O2 sensors (and their connecting wires)...
Thread Starter
Registered User
Joined: Mar 2011
Posts: 52
From: Vancouver, WA
Re: Idle Emissions FAIL
Reading the Chilton's tonight this tidbit peaked my interest: "..if the oxygen sensor fails to reach the closed loop mode or there is a very long period of time until it does switch into closed loop mode, replace the oxygen sensor with a new part."
My car takes significantly longer than the "205 seconds" it should take. Maybe not a huge thing, but I think could be a valid indicator - if not a red flag.
Not sure what the best brand of O2 sensor to buy is if we go down that road?(Going to check the exhaust system out first)
I've heard a few negative things about Bosch, but idk. The Delphi's are 45.00/ea. Bosch 53-60.00/ea. BWD 33-43.00/ea. I'd lean Delphi since that's closest to stock. Any thoughts?
My car takes significantly longer than the "205 seconds" it should take. Maybe not a huge thing, but I think could be a valid indicator - if not a red flag.
Not sure what the best brand of O2 sensor to buy is if we go down that road?(Going to check the exhaust system out first)
I've heard a few negative things about Bosch, but idk. The Delphi's are 45.00/ea. Bosch 53-60.00/ea. BWD 33-43.00/ea. I'd lean Delphi since that's closest to stock. Any thoughts?