Failed Emissions again!
09-06-2006, 01:03 PM
#1
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Failed Emissions again!
For some reason my car failed emisisons again! Mods are in sig. Computer was programmed correctly for SVO #30 injectors.
It fails on HC and is over by a decent amount.
CO is extremly extremly low. ALmost non existant
NOx are passing and seem to be a bit below the limit.
Last 3 tests i've done the results were roughly the same.
The CAT is basically new (GM Cat.). EGR was replaced maybe 2-3 years ago? New O2 sensors were put in 5 days ago (old ones were definatly responding slow). New MAF is in as well, less than a year old. TB and IAC passages cleaned thoroughly within the last few months.
Programming wise the timing has not been altered from stock. The cooling fans do come on a tad earlier, but only a few degrees.
I also have low IAC counts that will just barely bottom out at idle (500 rpm). Turning the AC on will bring the IAC up to maybe 7 counts or so and the idle goes up a tad as well. I can't find a vaccum leak so i'm guessing its the intake manifold. To me this seems minor and I shouldn't fail, shouldn't the O2's compensate for a vac leak?
Anyhow I'm beginning to lean to maybe a rocker being over/under tightend? Does anyone else have any ideas? IF it would help, I can post a diagnostic chart of the emission run... We do the testing here in BC on an IM240 machine.
My probable next steps:
-Reseal the intake manifold
-Put my stock 24# injecors back& set the comptuer back to those injectors.
-Maybe readjust the rockers (scared to death about this)
-Maybe adjust the BLM boundaries up a bit. I have a 2800 stall now and the avg speed for the test is 30 mph (50km/hr). Maybe my RPM is hovering on average a good bit higher now?
It fails on HC and is over by a decent amount.
CO is extremly extremly low. ALmost non existant
NOx are passing and seem to be a bit below the limit.
Last 3 tests i've done the results were roughly the same.
The CAT is basically new (GM Cat.). EGR was replaced maybe 2-3 years ago? New O2 sensors were put in 5 days ago (old ones were definatly responding slow). New MAF is in as well, less than a year old. TB and IAC passages cleaned thoroughly within the last few months.
Programming wise the timing has not been altered from stock. The cooling fans do come on a tad earlier, but only a few degrees.
I also have low IAC counts that will just barely bottom out at idle (500 rpm). Turning the AC on will bring the IAC up to maybe 7 counts or so and the idle goes up a tad as well. I can't find a vaccum leak so i'm guessing its the intake manifold. To me this seems minor and I shouldn't fail, shouldn't the O2's compensate for a vac leak?
Anyhow I'm beginning to lean to maybe a rocker being over/under tightend? Does anyone else have any ideas? IF it would help, I can post a diagnostic chart of the emission run... We do the testing here in BC on an IM240 machine.
My probable next steps:
-Reseal the intake manifold
-Put my stock 24# injecors back& set the comptuer back to those injectors.
-Maybe readjust the rockers (scared to death about this)
-Maybe adjust the BLM boundaries up a bit. I have a 2800 stall now and the avg speed for the test is 30 mph (50km/hr). Maybe my RPM is hovering on average a good bit higher now?
Last edited by TobyZ28; 09-06-2006 at 01:06 PM.
It's gov't run and it would be very hard to get someone to do that here...
09-06-2006, 05:08 PM
#4
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Re: Failed Emissions again!
http://www.fruitiondayspa.ca/toby/log.zip
Log file from freescan. I've created another excel tab to analiyze some of the data. The RPM never really go below 700 except barely at idle!
Would anyone suggest i change my cell boundaries a little bit? I'm on stock BLM boundaries (700/1200/2000 rpm, 32/50/80 map). Maybe with the new converter I should up it to something more like 1000/1500/2200?
Some more info from our "aircare" web page:
"If the fuel system is delivering a leaner than ideal air-fuel ratio, it may result in lean misfire and cause high hydrocarbons."
"If the fuel system is too rich, it also may result in high HC but will be accompanied by high CO as well."
This makes me think I'm having a lean misfire...
Need some advice, anyone??
Log file from freescan. I've created another excel tab to analiyze some of the data. The RPM never really go below 700 except barely at idle!
Would anyone suggest i change my cell boundaries a little bit? I'm on stock BLM boundaries (700/1200/2000 rpm, 32/50/80 map). Maybe with the new converter I should up it to something more like 1000/1500/2200?
Some more info from our "aircare" web page:
"If the fuel system is delivering a leaner than ideal air-fuel ratio, it may result in lean misfire and cause high hydrocarbons."
"If the fuel system is too rich, it also may result in high HC but will be accompanied by high CO as well."
This makes me think I'm having a lean misfire...
Need some advice, anyone??
Last edited by TobyZ28; 09-06-2006 at 05:22 PM.
09-06-2006, 06:04 PM
#5
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Location: Hell was full so they sent me to NJ
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Re: Failed Emissions again!
How about a leaky injector.... most of the cylinders running right, and producing low CO numbers, while one leaky injector spews some excess unburned HC's into the exhaust.
09-06-2006, 06:20 PM
#7
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Re: Failed Emissions again!
Might be. If the injector is just "slow" to close, it wouldn't show up. But if its stuck open slightly, you should see the drip.
Low CO and high NOx generally mean lean, but the high HC's would mean either a drip or a misfire.
But, a misfire richens the mixture as the PCM "corrects" for the air that flows into the exhaust from the misfire. Now you have one cylinder misfiring and three running too rich. That would raise CO and lower HC so I dont' know how much credance you should give to "If the fuel system is delivering a leaner than ideal air-fuel ratio, it may result in lean misfire and cause high hydrocarbons."
Low CO and high NOx generally mean lean, but the high HC's would mean either a drip or a misfire.
But, a misfire richens the mixture as the PCM "corrects" for the air that flows into the exhaust from the misfire. Now you have one cylinder misfiring and three running too rich. That would raise CO and lower HC so I dont' know how much credance you should give to "If the fuel system is delivering a leaner than ideal air-fuel ratio, it may result in lean misfire and cause high hydrocarbons."
09-06-2006, 09:27 PM
#10
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Re: Failed Emissions again!
Originally Posted by Injuneer
Might be. If the injector is just "slow" to close, it wouldn't show up. But if its stuck open slightly, you should see the drip.
Low CO and high NOx generally mean lean, but the high HC's would mean either a drip or a misfire.
But, a misfire richens the mixture as the PCM "corrects" for the air that flows into the exhaust from the misfire. Now you have one cylinder misfiring and three running too rich. That would raise CO and lower HC so I dont' know how much credance you should give to "If the fuel system is delivering a leaner than ideal air-fuel ratio, it may result in lean misfire and cause high hydrocarbons."
Low CO and high NOx generally mean lean, but the high HC's would mean either a drip or a misfire.
But, a misfire richens the mixture as the PCM "corrects" for the air that flows into the exhaust from the misfire. Now you have one cylinder misfiring and three running too rich. That would raise CO and lower HC so I dont' know how much credance you should give to "If the fuel system is delivering a leaner than ideal air-fuel ratio, it may result in lean misfire and cause high hydrocarbons."
Some extra info: I just checked the engine and the EGR is not stuck open. Depressing it manually at idle makes the engine want to die.
I'm going to lift the fuel rail tomorrow, I don't expect to see any leaks though. My car doesn't seem to have any trouble starting up or anything that would lead me to believe that its stuck open when the car's off.
If I don't find anthing wrong I'll throw my stock injectors back in and set the computer back to the stock programming.
Injuneer: Think the 30# SVO injectors are causing bad fuel atomization (Sp?), I know they are overkill right now (was thinking long term when i got them) but I can't see them being that big of a deal if the computers set right...
Last edited by TobyZ28; 09-07-2006 at 11:45 AM.
09-07-2006, 10:24 AM
#11
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Re: Failed Emissions again!
Originally Posted by toby360
Thanks sheobox, thats comforting
Is the PCM tuned for the 30# SVO's? If so, they shouldn't cause any problems.
09-07-2006, 11:46 AM
#12
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Re: Failed Emissions again!
Sorry, was typing that while the GF was talking last night Yes the injector flow constant was changed to what the svo's should be @ the appropriate stock pressure.... (Something around 32 lbs/hr or so if i recall)
Yes the injector flow constant was changed to what the svo's should be @ the appropriate stock pressure.... (Something around 32 lbs/hr or so if i recall)
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