Just bought a remanned 350 for my GTA. The car ran fine prior to the rebuild (hydro-locked from flood.) I installed a new LT4 hotcam and Trick Flow 195 heads with stock TPI. I've replaced plugs, wires, cap, rotor and ignition module; got spark to all cylinders. I havent been able to get it to idle at all. It will start up quick and easy without starting fluid but will not idle. It will run forever when giving it gas, good oil pressure, water temp and volts, no codes. I know for sure the TPS is completely misaligned, it was so before the rebuild but that never kept it from idling. I cannot set the timing correctly until it will somewhat idle. Turning the dist in either direction doesnt change anything. Below about 800 rpm it dies. It has 1/2 tank with half of it new gas and half of it 2 years old, going to drain it out tomorrow. Still open headers with an exhaust leak from the left exhaust gasket. Cleaned out the IAC and throttle body. Any ideas why it wont idle? Thanks.

 

Vacuum leak? Fuel pressure? Fuel pressure regulator bad. EGR? Just a couple of ideas.

 

Got a newer afpr, don't have a gage anymore but it was set to 48. As far as vaccuum leaks, I'm missing those two bolts on the bottom of the runners that's directly behind the injector and the runner itself. All vaccuum lines are connected, however there is one elbow fitting that I'm not sure where it goes. It's not for the egr solenoid but it comes off a T where one end goes to the plenum. Also I removed all AIR and capped off the header AIR lines.

Edit: The valve lash is loosened to 1/4 turn

 

If I was you, I would first make sure that all vacuum lines are on and no leaks, you need to verify the fuel pressure some how, so you can set the AFPR w/o vacuum line on for mid 40's to start out. Unplug the ECM connector so you can set base timing. As far as the TPS, you can adjust that without the car running with a DVM. Set the IAC as well, here is a link if you don't have it.
https://www.thirdgen.org/newdesign/tech/tpimod2.shtml
I will check in later to see if this helped.

 

I replaced the fuel in the tank, found where the elbow fitting went- there are no longer any vaccuum leaks. Adjusted the TPS to .54 and bought a fuel pressure gage and set it at 47. I had previously set the IAC to 1 1/8" but havent touched the speed screw. It runs better but still will not idle. It would dip down to about 400rpm before dying, still no codes. I can hear a little valvetrain clatter but thats about it. I unplugged the tan ecm wire and it would not start.

Edit: Could the camshaft change create a loss of vaccuum that it would not idle at previous settings? Maybe timing is way off? I have to give it throttle to get it to start as well.

 

The EGR valve or soleniod may be acting up, did you check that.
BTW, when you set the fuel pressure was the vac line off? 47-50 PSI with vac off, vac on should drop to 37-40 PSI if vacuum is ok and the AFPR is working.

 

I set the fuel pressure at 47 with the key in acc to power the pump with the vacuum line off. I don't know how to check the EGR or solenoid. I increased the idle speed a few turns with no improvement. Also messed with the timing and believe I have it right (best I can without a timing light.)

 

It is not good that the car will not run with the esc connector unplugged, what is up with that. All your doing is taking the ecm out of the loop so you can set base timing. Are you sure the base timing is 0-6*, the car should run at idle with that connector off. That needs to be figured out before you can move on.

 

Had the same problems with my '87 305 TPI Trans Am, maybe this will help -

My EGR valve was opening early due to a bad ECM. This was causing the car to die at idle, sometimes stalling at lights accompanied by a loss of low end power. This could also be caused by a bed EGR valve, or an EGR solenoid among other things.

Also, on my '85 305 TPI T/A I had a bad TPS, my car woudl idle high sometimes, and not idle at all other times. I replaced it in 10 minutes for about $30, problem solved, and what a difference in power.

On both of these issues the check engine light was on, and a scan of the trouble codes showed me the problem. A good scanner will really simplify life. If you don't have one, or can't afford one, either find one to borrow (some auto parts stores now loan them out here in Los Angeles) or pay a shop $20 or something to run a scan for you. Do what you think you need to, and then go back later to scan again and see if you got it right.

Hope this simplistic advice helps...

 

what size threads were those caps u used to cap the air tubes on the headers? Im trying to do the same

 

I just pulled the check valves off and took them to Lowe's. I think they were 3/8" I bought brass caps and used teflon on the threads.

I don't get any kind of check engine lights. Just for the ignition when I unplug the ecm wire. I hooked #1 plug wire to a spark tester and it fired once and it looked like it never fired again. Am I just seeing things or is there something causing that??