I know that this forum dislikes threads about tpi systems that are not in a F-Body from some of the threads I've read here but I'm hoping someone will be kind enough to help a former 3rd gen and current 4th gen owner out.

I have a s10 that I've put a 383 stroker into than ran just fine with the carb it had. I've since upgraded to tpi and have had a hell of a time getting things to work.

My motor is pretty built, not the bigest or badest but should put out about 400+ hp. It maintained about 16 lbs of vac when it was carbed. I bought a complete tpi intake and a custom pcm and wireing harness for it. The custom harness and pcm eliminates the emissions and vats. Also, it is a speed density (map) system. I bought refurbished 24lb lt1 injectors for it to replace the "good" stock 350 injectors it came with. Only 1 out of 8 actually injected. I also bought a new map sensor for it. The tps is set to .54 and at wot it reads a little over 5v. I was told it should be around 4v? I don't have any vac leaks that I am aware of. The egr is blocked off with a plate and I am using a 1 wire o2 sensor. The wiring harness and pcm are built for the older large hei efi distributor which is new.

My problem is that it takes a lot of cranking and maybe some help with starter fluid to get it to fire up and then it will run very poorly and stall easily. Also you have to hold the throttle open a little for it to even start and stay running. I've tried all kinds of timing settings to get it to start more easily but with out much luck. I have a new walbro 255 fuel pump and when the pump primes it goes up to about 45-48 psi and when the pump stops priming it falls to about 42 and stays there. And if I get it to start and run for any length of time it starts to backfire after a little while and then stall.

The prom is custom burned to work with the cr and other specs of my motor and I'm pretty certain that the pcm is working right. If I unplug the timing wire I get error 42 and if I unplug the tps I get error 21 so I think its working correctly. And it also shows 12 (no errors) when everything is hooked up.

I'm almost at my wits end but I've got one more guess. I don't think the iac is working. I've removed it and turned the key to on and the plunger doesn't ever move. It did move once after playing with it but that was the only time. I seem to remember that it should move out every time you turn the key to the on position so it can test itself.

Any ideas? I tried to cover all the bases and if you need more info just let me know.

 

are you sure the distributor isnt 180* out? or off a terminal? I think you also need to have your ALDL jumpered on pin A and B to check the IAC.

 

I don't think the dist is off, I have gotten it to run and if the dist was out that much I don't think it could run. Also, I used my timing light and it is set to 0btdc now but I've also had it set to 6-8 btdc with no real change. I'll jump those two terminals and see if the iac is working.

Thanks.

 

try unplugging the MAF too. I have been dealing with something close to your problem and after all the TPS, IAC adjustments along with min. air adj(idle speed adj) it still didnt run right. Then I disconnected the MAF harness and it would run ALOT better. Still not right but now I think it is the MAF and or relays.

Good luck!

also read here https://www.thirdgen.org/forums/tpi/...faq-index.html

check out post #15

 

try unplugging your est wire. Mine was doing this...unplugging it makes it run fine.

 

could be dumb question but did you program the comp for 24 lb injectors? also i believe the est wire is vital to controling your timing. if i remember backfires in the intake=lean.....exaust=rich. if too rich i believe the car goes into limp home mode.

 

Get a laptop and tunerpro hooked up to check the IAC step count. My IAC just stopped working (step count stuck on 145) last week for no reason - car just wouldnt idle without holding down the gas. After cleaning the sh*t out of it, the car went back to normal.