Check engine light again!!!

[Alfonso Gomez]

I recently posted my problem with the Check Engine Light. I got a code 33. So I changed both burn-off & power relays and still got the code 33. So I replaced the MAF sensor with a rebuilt unit (with a 1 year warranty). Now I get a code 36 which is a problem with the MAF burn-off circuit. So I replaced the relays again, disconnected the battery to erase codes and happily drove away. After about 15 minutes driving in the city the Check Engine Light came on again. When I got home I switched the engine off and got my trusty old bent paper clip to read the codes. Code 36 again. Removed the relays, cleaned the contacts and put in the old relays back on again. (The old relays are only two years old) Erased the codes and started the engine and let it idle for about 30 minutes with an occasional "blip" to the gas pedal. No Check Engine Light this time but have not got the time to take it out to give it a good run. OK, what do I check if I get code 36 again? Some manuals state that there is a burn-off module under the passenger's side hush panel, near the ECM. Is this true? Can it be the culprit? How do I test it before I go out and buy a new one? It bugs me to buy parts just to check out if the ones in the car are OK. Plus, I don't have another C4 to change parts with to see what is wrong with the ones in my car. DAMN SENSORS
Anybody knows where I can get a C4 (1987) shop manual? I even tried eBay with no results.

 

[JonM]

Do a google search for "Mass Air Flow Burn Off Circuit"

aslo you can get a manuel at

http://www.helminc.com/helm/homepage.asp?r=

 

[Alfonso Gomez]

This is an update. Things are worse now. On Sunday morning I disconnected the battery for 30 minutes and reconnected it. Drove the car to church and the check engine light did not go on while driving. Hit 110 mph and the car worked fine. When I started it after church, the Check engine light went on and the idle was very rough, intermittently missing at 600-700 rpm's. Hit it WOT on the way home and it climbed easily to 98 mph until I stoped at a red light. The idle was terrible and it started missing during acceleration like one or two spark plug wires worked loose. At home, I checked the wires and all 8 were in place and tight. I did notice that the exhaust fumes smelled like unburned fuel. What can be wrong? Still code 36 (MAF burn-off relay circuit problem).

 

[berky2500]

Mine has done this a few times, but only once in a while. I think that I figured out that it was because I was hitting the gas while it was trying to startup the car. This seems to mess up something in the computer.

Try:

1. Don't hit the gas when you are starting the car.
2. If you do have to hit the gas (something else needs fixed) to get the car to start AND the check engine light comes on, before you leave, turn the car off wait a second or two, then start it up again.

Every time my light has come on, and I drive it, it runs rough and sounds terrible as you say. As soon as I turn the car off then restart, it runs fine. I've made sure not to use the gas pedal to start the car, no matter how long it cranks, and I've not seen the light again.

Hope this helps...

 

[Mart]

I had roughly the same problem, I finally noticed that the wires leading into the relay connector were touching.

I guess over the years the insulation on the wires had shrunk back to expose them, and they would touch, very randomly, very frustrating I went through a couple of relays myself until I noticed this.

Check wires leading into the connectors.

Hope this helps
Mart

 

[Alfonso Gomez]

Thanks for your help. Will check this out.