Disaster Transport

DEMONIC_DAVE_2004

MEMBER
PONTIAC TRANSPORT

I have a 92 Transport with a 3800, mileage is uknown do to it is not the original motor. I got it cheap because the guy thought the head gaskets were bad, well after some testing and a few beers I discovered it was the infamous intake gasket leakiing. So I changed the intake gasket, started right up and no over heating, but the engine light was on when I got it and I didn't check the codes before I did the intake. So I pulled the codes and repaired the problems. The magnet fell out of the cam sprocket, so I put a new cam sensor, magnet, timing chain, oil pump. Great thought I was in the clear, but now I get a code 56 qdm B (Quad Driver Module) and the engine starts out fine but then stalls when reving or driving. Changed the coil packs, and computer, no change. Plus the transmission makes a funny sound that I thought was the engine misfiring. Hoping for a sticky solenoid or bad wire on that one. Any help would be appreciated.

1 Reply

KB42

MEMBER
13 POSTS

Mine was a bad throttle body position sensor. However they are also known for bad MAP sensors.
Try unplugging the TBS and rev the motor. If you find it jumps up and down in speed, with it unplugged and plugged in then it probably is bad.
Coil packs also are a problem with the 3800. Swap them around, and/or replace all 3 before you give up.

Also I took off my Throttle Body, and took it all apart and cleaned it. It was black from the intake problem and misfiring. The idle air control plunger also was stuck and black as well. Carb spray helped there. Also did you decarbonize the intake when you had it off? And they are known for warping, so you want to replace all the orange gaskets. Another thing, be sure you replace the PCV valve which on my 95 was on left side of the intake manifold, underneath what looks like a plastic cap, resembling an oil cap.

Of the 3 motors GM made for these vans, I truly think the 3100 was the best overall, as it used a regular Aluminum intake instead of the junk PLASTIC ones used on the other 2 engines.