Subject Car: 1992 GXE

Recent History: Replaced Injectors, Engine Coolant Temp. Sensor, O2 Sensor, PCV Valve, Fuel Filter, plugs, wires, cap and rotor.. Verified fuel pressure regulator operation.

After repairs listed, car ran perfectly for about three weeks. Recently it has begun running roughly periodically, often immediately after the engine is started. It appears that it is flooding. This condition will persist for a couple of minutes and then it will begin to run perfectly. It happens randomly at startup, sometimes going two to three days between episodes. It has even happend a time or two while traveling at 30-50 mph. When it happens at idle, gray-black smoke is seen in exhaust. No codes have been stored.

I am thinking the problem is the air flow sensor immediately downstream from the air filter. However, the best price I can find on a sensor is $129, so I don't want to buy one if it is not needed. Is that the direction I need to head?

Thanks

 

Clean the MAF connector and see if it does any good. This is the most common way to fix a MAF problem. Also, are you SURE all the injectors are functioning properly? It's not uncommon to get hold of a faulty injector.

 

Yeah, maybe the other 4 injectors are leaking?
Pull the plugs and see which one is fauled by fuel/black deposit.

 

I am as sure as I can be that the injectors are not the problem. The problem did not begin to appear until at least three weeks after the injectors were installed. The car is running perfectly except when it goes through one of the episodes. The problem mainly occurs at idle, and usually after startup. This only happens one out of five to seven start ups. It always clears up in a couple of minutes when it does occur. The gray-black smoke that I mentioned in the original post is not extremely heavy. It is reasonably faint.

I will clean the MAF connector to see if that helps. Could the symptoms that I am describing be attributed to a faulty/malfunctioning air flow sensor.

 

You can get a used MAF (mass air flow sensor) at just about any junkyard for cheap, even some people with parts cars have them in the for sale section. All 3rd gen (89-94) MAFs are the same.

I don't have any experience with the VG engine, but my VE had some similar symptoms. I had a bad coolant temp sensor and the IACV was acting up. It seemed like it was flooding bad, had trouble starting, idle surging and high idle speed.

I put in a new coolant temp sensor, bought a spare IACV, thoroughly cleaned it and swapped it with the stock one. I also bought new gaskets for the IACV and the throttle body. Everything is fine now.

I don't think the two were related, but I think the IACV was in bad shape before, then the coolant temp sensor went out and really caused a problem.

I know you replaced the coolant temp sensor, but I would also take off your IACV, clean it out really good and put in a new gasket.

 

i have a MAF (mass air flow sensor) for sale.. it does work, so PM me for details

 

I have a MAF, too!! I have a couple parts cars you can pick off of also, I'm only about 2 1/2 hours from you.

 

Thanks for the suggestions. Will inspect/clean the MAF connector and the IACV. Is there a way to test the MAF and the IACV to determine if they need to be replaced before actually replacing them?