Whats up guys here is the scoop i have been helping a friend work on a 94 pontiac trans am. We have done a few mild things such as lt4 cylinder heads, lt4 hot cam and matching springs, full length headers, x pipe, flowmaster, egr valve eliminator, no catalytic converter, and a small wet nitrous kit, some mild computer tuning, it does have a th-350 tranny in it now to we ditched the 4l60. Well just recently after installing the nitrous kit the car will not run it will not idle and you constantly have to give it throttle to keep it running. We have brand new o2 sensors about 2 or 3 months old. We also replace the opti with a GM opti about 3 or 4 months ago. It has farely new msd 8.5mm spark plug wires and brand new plugs just replaced. We also tried a new fuel filter with no luck. I can hear the fuel pump prime so i believe its ok i have no way to psi test it now though because of the nitrous install. Any input or advice would be greatly appreciated thanks.

 

Check the IAC.

 

IAC or vacuum leak

 

Thats what i was begining to think was IAC, fuel pump, or a tps. I will check the IAC thanks guys later.

 

So we checked the IAC no luck. So my friend brang over one of his friends and he says that its only firing on 4 cylinders now. He checked it out and you can actually touch #1234 cylinders header tubes they are cold when its running so wtf. He checked spark and it got spark so now im lost. Maybe we got bad fuel injectors i dont know is there any way we can test the injectors. It will not start either now it gets close but wont actually run.

 

if you do get it running one way to check an injector is to unplug the injector and see if that effects your motor. when you unplug the injector you should hear your motor get weaker.

 

So it was running fine before with just the bolt ons, heads, and cam? Did it just start acting up after the nitrous install?

 

2 weeks after nitrous install. But the bottle has never been ran on it yet. It has ran ok up to the nitrous install and then it started doin this. What are the chances of bad injectors slim chance 1234 cylinder injectors are bad but i dont know soda.

 

Sure you mean 1-4 that are not firing? It's actually the first two cylinders on each bank? What kind of nitrous system did you install?

 

wet kit

 

Switch the 4 working cylinder injectors to the 4 nonworking ones. See if the problem follows or stays.

 

Thats what we were thinkin we may try to do that. We might go get it fuel psi test and get the opti checked out for real anything else you guys recommend.

 

You said you had some spark right? Would definitely check fuel first.

 

Yeah we took a spark plug wire off #1 and put a screw driver in it and grounded it to the header. It shot a good arc across the gap so i believe its ok. But i dont know if its firing at the right time but i just cant see 1-4 injectors going bad at once but i guess anything is possible. This damn car is cursed so maybe. thanks jason.

 

Yea check fuel and spark. You can rent a fuel pressure gauge at Autozone and get your money back when you return it. After that get your coil and ICM checked out at a parts store too.

BTW thanks for the kind words about my car!

 

Thanks jason and soda for the input. We wont get to test any of the components till this weekend but i will keep you guys posted. One more question now that we have installed the wet nitrous kit will we have problems psi testing the fuel rail because of the schrader valve being removed?