Hello, I have a 94 3.4 auto that I just bought. Car ran terrible so I got it real cheap. I replaced plugs, wires, t/p, cleaned throttle body, and changed all the fluids. When I got done it ran almost perfect, just a tiny bit rough and a little smell like it was running rich. I ordered a scanner to pull the codes and fine tune the car a little but encountered a problem yesterday. I descided to wash the engine compartment and clean it up a bit. Well guess I knew better, at the car wash the car started to miss, and all the way home it was at a fast idle and would not accelerate without dying out. After I limped it home it finally died and would not restart, just cranked. I pushed it in the shop and checked every single connection I could possibly think of. They are all completely dry with no signs of corrosion. After checking everything I found that I have fuel pressure, ( pump runs and sprays at the valve on manifold) and I have fire ( pulled a few wires and held with screw driver while cranking). Shot a little starting fluid in and she fired right up till it burnt off. ( injectors are obviously dead)This morning the car fired up, 2000rpm idle, but will throttle up with a noticable dead spot at about 2200rpm. Possibly it will dry up and come out of it but I want to find the source so it dont happen again some day far from home in a rain storm. ANY IDEA'S!!! Thinking maybe it could be related to the vats, although it should disable the starter as whell as the injectors.

 

owch............. ya I cleaned my engine compartment one time on my last truck, removed battery and washed then let sit for 2 days to dry outside (good weather). I never had a problem.

I also have a 94 3.4 auto, best bet is to NOT RUN IT right after you wash it... now the damage is done if you fried something, dont start it again till it dries out for a few days, and then see. Take an air hose and blow off the top of the engine and make sure there is no standing water on top and in the spark plug holes.

 

Update,
After almost a week the car has not changed. If it sets for about a day it will fire up and run normal for about a minute, then it starts to idle fast and wont rev.. The only code its showing is the TP sensor which I replaced just a day before I washed the engine compartment. I've even tried letting it run until it was good and warmed up, about 15 minutes. There are no other codes and it holds a solid 40 psi fuel both running or just key on.
Any ideas???

 

check fora spark problem next.......... could be wires or the coil packs.I would recomend you replace the wires (in your case) if they are more than a yearand make sure that you have them secured where they are supposed to go so they wont rub.

Ihad a bad coil pack on my s10, to test:
take the wires off each pack (dont get them mixed up)the 2 on the same pack need to come off and then have someone crank the engine (if it starts, turn it off right away) what you are looking for is cross firing, if the posts spark to each other you have a bad one... they should spark to a ground source.

 

Good news!!

I checked and tried everything I could think of and nothing helped. Then I decided to start over with what I thought would be the most likely culprit. I bought another TP sensor ( replaced with new one same day I washed and killed it) installed it and it fired right up and is running perfect now. Either I damaged the sensor when I washed it, or it was bad and just a strange time to go out. Anyway its good to go now, thanks for the help.

 

First you should take care of the TPS problem, as it can cause many weird problems. After taking care of that,and if the engine is still sick, check the coils as your cleaning may have generated carbon tracking between them, and the ignition control module under the coils, burnt ignition wires (wetting wirescan cause them to arc and burn tiny holes through the insulation). Look for blown FI fuses (fuses 9 & 10 under hood fuse box), you can use NOID lites to see if the injectors are being fired. Also check the 3 timing reference sensors: CPS (camshaft position), high res crank position sensor (24X), low res crank position sensor (3X).

 

Thanks Pete I got her going. Like I said I replaced the TP sensor again and all is well. It was just odd that a new sensor would go on and work and then go bad the same day. Maybe the wash damaged it or maybe it was just a coinsedence. Anyway, for 196k mile car it runs pretty good. I had already done plugs wires, ect., all the normal stuff that hasnt been done in who knows how long.
Now if I can figure out the ABS light the car will be problem free. Brakes work just fine, it just has the light on.

 

Glad it is all better.
To find out exactly why the ABS light is on you need to get the ABS system scanned. However; you may want to check the condition of the connectors at the ABS unit, and make sure all the bulbs on the high mount brake lamp are working, and the same for the other brake lamps. For some weird reason GM tied these lamps into the ABS system and cause the ABS lamp to go on when they burn out.