Check engine light once in a while?
Thread Starter
Safety Car
Joined: Oct 2007
Posts: 4,426
Likes: 229
From: Pennsylvania
Check engine light once in a while?
My 85 stock L98 has a true duel exhaust on it. The catalytic converter was removed. (Antique Plates) No emissions neccessary. The air pump is still in place as well as the EGR valve. I can be cruising at about 50 mph for a few miles and the check engine light will come on. Most of the time it's while I'm in overdrive or the cruise control is set. (4+3 transmission) There is NO problem with the overdrive. After about 5 minutes while I'm still cruisng at same speed, the light will then go out on it's own. Why does it go out on it's own? Or if you turn off the ignition and restart it, the light will be off. The code being stored indicates EGR problem. Could the system be trying to tell me that the catalytic convertor (that's not there any more) is not working? The car runs fine with no problems while this light is on. Should I just disconnect the light, or am I causing a future problem with an EGR and no catalytic converter?
Last edited by FOURSPEEDVETTE; Apr 22, 2012 at 02:49 PM.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Nope - it's telling you that EGR was commanded and it didn't happen. The design relies on a heat sensitive switch grounding when exhaust passes over it. Your ECM didn't see that ground so it sets the Code. When conditions for EGR pass, it could care less, so it ignores the switch signal - unless it remains grounded, but from what you describe, that isn't happening.
Since when did an OEM vehicle with a CAT become exempt from the FED rules?
Since when did an OEM vehicle with a CAT become exempt from the FED rules?
Thread Starter
Safety Car
Joined: Oct 2007
Posts: 4,426
Likes: 229
From: Pennsylvania
Nope - it's telling you that EGR was commanded and it didn't happen. The design relies on a heat sensitive switch grounding when exhaust passes over it. Your ECM didn't see that ground so it sets the Code. When conditions for EGR pass, it could care less, so it ignores the switch signal - unless it remains grounded, but from what you describe, that isn't happening.
Since when did an OEM vehicle with a CAT become exempt from the FED rules?
Since when did an OEM vehicle with a CAT become exempt from the FED rules?
Last edited by FOURSPEEDVETTE; Apr 22, 2012 at 08:47 PM. Reason: typo
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Emission test or no Emission test, no vehicle is exempt from the Fed Requirement to have a CAT - they even make reporting violations/tampering easy with a link at the epa site, though they prefer to prosecute shops, Dealers, etc. Speaking of Dealers, a Dealer that accepts a tampered vehicle as a Trade-in has a requirement to report it (along with fixing it if they want to resell it). Didn't any of you take Civics in High School? Fed Law does supersede State Law from time to time. None of us are special - or exempt from these requirements and the majority of car owners get it. For the few that don't, I don't think they're causing much harm, but like a neighbor that cheats on his/her taxes while you pay your full dime, it tends to rankle you from time to time.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Jumper the ALDL pins A&B, turn on ign sw and count the flashes to verify a code "32" has been set.
If so it is indeed an EGR problem.
I have the same symptom with my "new" '88. Rather than diagonse the fault I've ordered a new EGR Temp sw. If that doesn't solve the pesky SES light issue I'll install a 160 deg T-stat as the ECM will NOT call for EGR untill coolant temp is >175deg F.
If any issues with the "no cat" problem, just pick up a used one from a bone year, gut it and install...
If so it is indeed an EGR problem.
I have the same symptom with my "new" '88. Rather than diagonse the fault I've ordered a new EGR Temp sw. If that doesn't solve the pesky SES light issue I'll install a 160 deg T-stat as the ECM will NOT call for EGR untill coolant temp is >175deg F.
If any issues with the "no cat" problem, just pick up a used one from a bone year, gut it and install...
Drifting
Joined: Dec 2011
Posts: 1,439
Likes: 23
From: mesa az
God Bless Alabama !
I see nor reason unless you live in a big city why you should have to runa restrictive exhaust system. I live in Mesa AZ Maricopa county and emissions are law. I could register it in another county to avoid this and gain the HP I am being denied. I am having second thoughts due to resale. If I decide to sell the car I will have to spend several hundred dollars just to sell the car. Not sure I want to go through all that. If you dont have the same regulations then run it brother ! How loud is it ? So bad you cant hear music ?
Thread Starter
Safety Car
Joined: Oct 2007
Posts: 4,426
Likes: 229
From: Pennsylvania
Emission test or no Emission test, no vehicle is exempt from the Fed Requirement to have a CAT - they even make reporting violations/tampering easy with a link at the epa site, though they prefer to prosecute shops, Dealers, etc. Speaking of Dealers, a Dealer that accepts a tampered vehicle as a Trade-in has a requirement to report it (along with fixing it if they want to resell it). Didn't any of you take Civics in High School? Fed Law does supersede State Law from time to time. None of us are special - or exempt from these requirements and the majority of car owners get it. For the few that don't, I don't think they're causing much harm, but like a neighbor that cheats on his/her taxes while you pay your full dime, it tends to rankle you from time to time.
Don't get yourself too "rankled" but most legally titled older cars with classic car plates or antique car plates with "custom exhausts" have no catalytic convertor on them. If they have regular plates indicating that they need a state inspection including emissions testing, then the law you speak of is correct.
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I got the random SES light during cruising because my EGR solenoid had failed and the EGR valve was frozen by carbon. You need to look at the whole system before just replacing the EGR temperature switch, which might not be the problem.
