A friend of mine recently purchased a 1999 GMC Sonoma (2 wheel drive and 2.2 liter 4 banger with automatic transmission) from a local auction. Advertised as driving and running, although we later found out that is a bit deceptive as it says it does not have to be road safe or road legal to be considered as driving and running. Anyway besides all that and nothing to do except keep it now, the original idea was to fix a few small things, add a radio, and resell it for profit...bla bla bla
Anyway the truck was misfiring badly when he first started it at the auction location. Suspected the cat was clogged, so cut it off....no change, just 10x louder. So he had it towed back to my place. I pulled all of the plugs. They turned out to be Bosch Platinum +2's. Cylinder 1 and 2's plugs appeared to be in a lean environment. The plugs from cylinder's 3 and 4 appared to be in a rich environment and covered with soot. So I cleaned the 4 plugs with a wire brush and reinstalled. Also made sure the "gap" of the two grounds on each plug were even, as some appered to be slightly closer to the electrode than others. The metal on these grounds seems to be softer and thinner compared to any other spark plug I've seen.....
Anyway I ran a resistance check on the 4 plug wires too. Three gave readings, one gave absoultely NO reading at all. Thought there was an internal brake in the wire. So we installed a new set of plug wires without any change.
Tonight I welded the cat back onto the rest of the exhaust and he replaced both of the coil packs with new units. No change.
Motor appears to be misfiring really badly. The motor is moving around inches in each direction. It has no power at all. Also if you turn the lights on, they fluctuate in brightness. Just to show how bad the "misfire" is (if it is truly a misfire or not) if it is causing the alternator to charge at an inconsistent rate.
There does not appear to be any coolant in the oil or vise versa either.
Actually today after the new coil plugs were installed, it would not start without putting the accelerator pedal to the floor (so that the injectors are disabled during starting)
Also you can smell A LOT of gas when starting the vehicle or when it is running.
Perhaps the injectors are screwed up? If this were the case it is probably more than 1. I think the intake manifold would have to come off to get to these. This small 4 banger is really packed in there......nasty!
Whoever had (or worked on) this truck prior was really a dumbass. The wire that is supposed to hook up to the A/C compressor clutch was left dangling and got chewed up by the radiator fan while the plug which was intended to plug into the intake air temp sensor (in the air intake tube) was jammed into the A/C plug. They are clearly different plugs too, not even identicle!
The "service engine soon" light is also on. We are working on getting a code reader to read the codes. I am guessing it will show a bunch of misfire codes and that is it.
Does anybody have any GM experience or any suggestions relating to these problems?
Thanks in advance!