'89 T/A rebuilt motor running rough/hard start...

[CreepingDeath94]

Alright, I just rebuilt my engine in the '89 T/A. It is a 4 bolt 350 bored .030 over, standard 350 roller cam lift/duration, dished pistons to bring down the compression due to the 305 HO heads I have on it. It has an MSD coil, cap, and rotor kit. Aside from that, it is basically stock. I have the original 305 intake crap including the lower 19 lb. injectors on this engine. The PROM I have is for the stock 350 motor. I sent it out to be reprogrammed for the 19 lb. injectors, to eliminate the cold start (if it was even equipped), and to eliminate the EGR.

After doing the PROM reprogram, it still takes forever to get her started. It takes turning it over forever and almost starting and sputtering for a while before it eventually fires and idles like crap before holding steady. Once warm, it runs a little better but its still not right. If I shut it off after its warmed up, it does the same thing but to a lesser degree.

My question is what is the problem? I thought it was fueling at first due to the 19 lb. injectors not delivering enough fuel. But after reprogramming the PROM, that should have eliminated it if that was it. The car has been timed to standard timing on that year T/A. All the sensors have been replaced with new for the 350 motor. Fuel pressure checks normal. I am at a loss. Any help would be appreciated.

[97cavalier]

you might need to adjust your fuel preshure regulator due to it is bored and needs more fuel.

[88camaroproject]

id say timing. you say its timed but are you unplugging the connector on the passenger side of the engine bay so the computer dosnt mess with the timing. cuz i forgot to once and thats exactly what it did.

[88camaroproject]

have you pulled a plug to see what it looks like now that you have run it?

[CreepingDeath94]

I performed the proper timing procedure...disconnected the computer basically yea. I didn't do anything to the fuel pressure regulator yet as I thought the PROM would fix that, but I thought the ergulators were the same between the 305 and 350 anyway...just the injectors are different. I could be wrong. As far as the plugs go, I have only run it like 3 times and the plugs don't show much of anything yet. In other words, they appear fine and not showing signs of rich or lean yet...need mroe time/miles on them. I just didnt want to drive it like it was until I get it right as I dont want to mess up a brand new motor by running it too lean or something dumb. I was so close to gutting the regulator or just replacing it with a higher regulator but skimped out as I approached my time deadline and just had to get the motor in the car and out of the place I was storing it at...I hope thats not the problem. Anyway, thanks for the input thus far, anything else comes to mind please let me know. Ill check the regulator out tomorrow and look into a higher pressure one.

[CreepingDeath94]

One more thing just occured to me. If I replaced the throttle position sensor, but it wasn't set right, as it can move and is adjustable, would it run like it is? Or would it just not run or run eratically at a certain rpm range? To be honest, if it is wrong, I dont have the tools to set it at the proper voltage position...so if this is the problem, then I need to take it to my buddy mechanic and have him adjust it anyway, just thought Id ask if that could be the problem. Thanks again guys.