Started all the sudden one day about 2 months ago. Stumbled real bad under throttle, no power. I scanned the car, and saw no O2 reading. replaced the O2 and the entire harness. Doesnt throw a code anymore for the O2. BUT it still has the same stumbling problem. It gets worse when its warm. This lead me to think it was the CTS, so I replaced it, but that didnt solve it. I havent had a chance to scan the car again, or to check the fuel pressure, but what else could it be?

 

Any error codes? It's eaiser to scan the ECM than it is to drain the cooling system and change the CTS.

 

tap on the mafs and see if the idle gets crazy again

 

i have the same problem with my car and i tryed everything i checked the codes and im only gettin a code 12

 

whats the mafs? me and 91transamgta been trying to get his car going since a week or more,just the same ol spudder,and miss.its like theres a senser not working or a vacume not working

 

Sounds like lack of fuel pressure to me. Its not to hard to check. If thats not it, I would guess vacuum leak or bad MAF.

 

ya it was the map senser 4 sure.put another one on er now she runs mint.

 

I have a speed density conversion on my car, so no MAF sensor. I scanned the ecm yesterday and it appears that everything is working as it should. I have a Fuel pressure gauge im going to snake under my hood and drive around a little so I can see what the pressure is doing. Maybe I cant put off that racetronix pump anymore

 

That's a good idea if there are no error codes.

 

is it possible for the pump to work ok when cold, but act up when hot? I guess its possible, but Ive never seen it before. I always thought when a pump was bad, it just stopped :shrug:

 

Fuel pumps, like all electric motors, work worse when hot. Usually the fuel keeps them cool, however. Thats why electric fuel pumps are installed in the tank. Also, you don't need to drive it around with the pump attached. Just test while in the driveway. If the pressure drops when you increase throttle, then you found your problem.

 

ok so I drove around and the fuel pressure stays pegged at 43 at WOT. I also swapped in a good used MAP, which didnt help. I tried an extra 730 ecm, no dice. Its gotta be ignition related. I have a brand new MSD coil on there now, and a recent module but I guess those are next to try?

 

All injectors just ohmed out at 13 ohms

 

failing ignition module?

 

hmm, guy I know has put in his vote for a bad pickup coil....maybe I should just pop in a new distributor?