Check engine light on 1994 Chevrolet Lumina

Check engine light comes on ONLY when driving at high speed when I let off the gas feed. Like the interstate. When cold, it acts like a spark plug missing or fuel interruption but gets better after warm-up. There's a foul odor and raw gas smell at the tail pipe, but not always. Had the car checked for leaks. None found. Starts fine and has good power. Gas mileage is good. Replaced,oxygen sensor, plugs, wires,fuel filter, and other parts. Had fuel pump checked and it's ok. The only 3 things left(I think) are the idle air control valve, coil, and injectors. Going after the injectors next. Car has 108,000. Any help will be appreciated.

by in Fairmont, WV on April 08, 2009
8 answers 6 comments
ANSWER by on April 09, 2009
I think you are going after this problem backwards. There are various reasons for the check engine light to illuminate. It's always best to pull the code first to see what the problem is and then diagnose why the system is setting that particular code.
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COMMENT by on April 09, 2009
Already had codes read 3 times on this vehicle while the check engine light was still on. The last "mechanic" said it gave the code for a bad EGR valve. Replaced it. That wasn't the problem but it sure was expensive!!! The light still comes on while driving at high speed on the interstate when you let up on the gas. You can drive it hot or cold in town and it never comes on. I was told by an older and more experiened mechanic that pulling the codes on these cars does NOT necessarily mean that's what is wrong. It could be something else causing the code to show that a part is bad when it isn't. Like an EGR valve for example. If the computer can't tell someone EXACTLY what the problem is what good is it? It just leaves one guessing. The very thing I'm doing now. At any rate, I thank you for your help in trying to solve my problem.
COMMENT by on September 14, 2010
Mine does the same thing, so if you find out will you please let me know?
COMMENT by on September 14, 2010
yea i gave up on mine. i think of it AS A DUMMY LIGHT NOW. when it is raining, the light doesnt come on, if i drive around the city, it doesnt come on, only when i drive the interstate does it come on. My mechanic hooked it up and it stated it was running rich. so i use ethanol free gas, and it still comes on.
ANSWER by on June 05, 2010
for all the people thats having proplems with light that stay on. change the gas to 97 oct and tighten the gas cap. if it does not go off dis connect the possive side battry for about 5 mins .this will reprogram the computer.thanks frank
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COMMENT by on September 16, 2010
the highest gas we have is 93, and they told me it is not good for my caprice. and i went and bought a new gas cap to see if my gas tank would stop making popping noises (it releases pressure for some odd reason when the gas is low) and the check engine light still appears even after my new gas cap. my mechanic says he disconnected the positive side plenty of times, but it still appears.
ANSWER by on June 26, 2010
Can be the cam shaft, the cam shaft follower of the fuel pump. You are lucky to have the engine running. Get rid of the car.
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COMMENT by on September 16, 2010
what is the cam shaft? what does it do?
ANSWER by on July 16, 2010
Take your car to Autozone where they will check free of charge, the codes for your problem. Also AAMCO does this as well--for free. mcstanley
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ANSWER by on July 19, 2010
whats funny is my 89 caprice classic does the same thing that your lumina does..if i drive around the city, the light does not come on...if i hop on the interstate, better believe within 10 mins it is shining bright. but...i did not have this problem UNTIL i changed the fuel filter, fuel pump, and the O2 sensor all at once..so i was thinking to change the O2 sensor and it may go away...it didnt. Unplugging the pos side of the battery did no good.. some people told me to replace the EGR valve that was no good, but was still hooked up..while the new one was hooked up, the check engine light came on 3 days later. so i figured that was not it. Autozone will not get me a diagnostics because my car is too old; so i keep guessing as you do..still avoid the interstate as well if i can...maybe i can find a person who is very knowlegable about my caprice and will not keep me guessing...
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ANSWER by on June 06, 2011
catalyst convertor problem
COMMENT by on June 08, 2011
oh yea. I had that replaced when I first got my car in 2009. My check engine light never came on until I replaced the 02 sensor, I'm thinking the new sensor has something to do with it. We changed it several times and the light still comes on.
ANSWER by on September 25, 2011
the code i am getting from my aunts car doing the exact same thing was code 32 - The ECM codes book states it could be three things or one of the three...(1)a barometric pressure (BARO) sensor circuit failure, (2)a an Exhaust gas recirulation(EGR) valve diagnostic switch that is closed during the engine start up(not the case) or open when EGR flow requested by ECM or (3) Electronic vacuum regulator valve (EVRV) error (EVRV controls the EGR vacuum) - hope this helps someone
ANSWER by on April 04, 2014
I had the exact same problem along with a few other issues with my 1990 Lumina. The check engine light was easily fixed by cleaning the mass air flow sensor. It only cost me $10 to get rid of that problem. My car drives and idles better and my check engine light is gone and has not come back. The car used to loose power when accelerating, stall when stopping, idle very high, and had a fuel smell because of it running very rich. I had countless mechanics look at the car and check the codes and they could not figure it out. So I did some research and found the problem myself. I have no faith in mechanics because I have always had better luck figuring car issues out myself. My advice is clean the mass air flow sensor and see what happens it is cheap and easy. The sensor is usually on top of the engine and is only attached with two bolts. Start at your air filter and follow the system up and your sensor should be there somewhere.
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