My problem started about a week ago when I was driving down the road at about 45, the Service Engine light came on but there was no detectable problem with the way the car was running. The light went out next time I drove the car and when I checked the code, it was 3-4. The car appeared to be running fine and a week later, the light came on and at the same time the engine appeared to die for a second and then ran normal. I put my scanner on and it said code 3-4 again and the indications for the MAF were around 8 g/sec at idle and seemed to increase with engine speed. I took the MAF out and nothing seemed amiss, the terminals appeared clean, so I put it back in and the car ran fine.

Today, the problem seems to have gotten worse, at times it will run fine, but at times the idle hunts around from about 300 rpm to 1100 rpm and will die once in a while. I disconnected the MAF and it had no effect. The weird part is that with the MAF disconnected, the scanner still seems to have a MAF reading as before and it appears to vary with engine speed as before. I am not sure how it does this with the MAF disconnected. I tried tapping the MAF with a screwdriver handle and that didn't seem to have any affect either. I sprayed some carb cleaner on different places on the intake tract to check for vacuum leaks and there didn't appear to be any. Now the light comes on a few seconds after startup and gives three codes, 3-3, 3-4, and 3-6.

The car is an 86 L-98 with about 79K on it and has been running fine up to this point.

Any ideas?

 

MAF relays

 

I checked in the factory service manual and it said to clear the codes and run it at 2000 rpm or until the light comes on and check the code, if 3-4, which it was, disconnect the MAF and clear the codes, run at 2000 rpm until light comes on and check the code, I did and the code is 3-3, in which case it said it is the MAF. Is there anything else, such as the relays as was suggested or should I just buy the MAF?

Thanks

 

realys cost $17 ea at auto parts stores
MAF (rebuilt) costs $150+

Start cheap and go from there.

 

No, anytime you get a MAF code, replace the relays. The manual doesnt say this, but every MAF code can be caused by the relays themselves. If you replace the sensor, you have to replace the relays anyway, so you might as well do them first to see if theyre it.

Theyre cheap enough that its not really an issue.

 

When this happened to me, it was the relays. I replaced them and all was well.

 

Thanks,
I will pick up both relays and see what happens.

 

I went to AutoZone because the Chevy dealer was closed today and got a MAF relay, they had two different part numbers for the same application and they did not have a burn off relay. I got both of them and replaced my MAF relay and so far all appears to be cured.

 

On my 89, both MAF relays are the same. Maybe autozones computer has a wrong number in their listing unless GM changed it between 86 + 89

 

They are actually the same part, despite being different PN's.