88 Suburban Error Code 42???

[draston]

It seems that I can temporarily solve the problem by just turning off the vehicle and restarting, the light goes out and the truck runs ok, that is until that old check engine light pops back on.


I have the same problem on a 95 GMC suburban. It started after I hosed out the engine real good at a car wash... Same exact problem... Looking for a fix...

[dirty dan]

dpresto31, I responded to your private mail. Did you try what I suggested with the O2 Sensor? If so, how did it work for you?

[draston]

OK, this wont seem logical as a fix, but this is what I did and the error light is gone, and the car runs normal without restarting it 6 times...


I bought a can of STP throttle body cleaner and a new pvc valve.

I took off the air cleaner and soaked the entire throttle body area, including the area behind the trottle body, there the main spark plug wires goes. I used the entire bottle all at aonce. started the car without putting the air cleaner metal thing back on. I let it run a minute or two, ran really rough.

I put everything back the way it was, started it again, it smoked some out the exhaust.

Car has run fine for a week. Error code is gone and runs faster than it did...

Anyway, how this cleared out the code and fixed the rought running and slower accelration, I have no idea, but it did...

Andrew

[Delta Dart]

Andrew,
Sounds like a logical fix to me. Your problem started after you washed the engine bay. Could have been wet wires and you may have dried them with the throttle body cleaner. Good job!
.

[jt900]

Hi, I have been having the same problem with my 90 5.7 TBI. Found two faults so far after replacing almost everything at least once. the first was defective EGR. but the code was from the electrical connector at the coil. like most owners I try to keep the engine clean. I created this problem with the high pressure washer. the connector has a 1/4 " piece of white foam in around the pins. this nasty thing is porous and sucks in water. And the water is conductive......partially shorting out the coil.
I sprayed it with carb cleaner and blotted it dry in a paper towel. No more code!!!! Hope this is helpful for someone else as I see you got yours with a similar fix.

[ASEMasterCertMech]

Dude, G.M. had a problem with the distributer shaft wearing, oil then traveled up the shaft and dammaged the pick up coil in the distributer.Once the coil is dammaged, you need to replace both the pick-upcoil and the control module. The module is effected by the resistance in the pick-up coil being out of spec. I have done many of these repairs in my shop.

[Cam7]

I had this problem on a 88 Grand Prix 2.8 I did every thing just about drove me crazy. Finally like the one post says I found a bad Harness connection at the ECM. Fixed it and problem solved. The is a post =
www.troublecodes.net/articles/ about false code 42.
Dirty Dan on the cam change how high of a lift did you go? Iam going to do a Cam change on my 90 1500 5.7 and dont want the trouble you had.