87 Z28 LB9 Auto trans. Edelbrock catback, headers. No egr whatsoever, no air pump, no cat, Vortec heads, SDPC TPI baseplate, stock cam, LT1 24# injectors. Bi passed TPI coolant at air intake. adjutable fuel pressure reg. 58 psi

Problem run rich under throttle according to the AFR gage. Does not seem to be getting enough fuel at idle. Idles rough and rpm's flucuate between 1100 to 500. Often stalls when surging. Have to put it in neutral when I stop. Seems to idle better then.

I read somewhere "and of course can't find the article on putting vortec heads on a TPI 305" that TPI cars idle bad with vortec heads until the Chip is updated

Wanting opinions on if anyone thinks this will completely fix the problem or if something else might be wrong.

I have checked and fixed a couple of vaccuum leaks. There are not any more. I triple checked. No signs of head gasket leaking either although I have not done a compression check.

Anyhow please give your input

Thanks

 

is that alot of injector for a 305?

 

I also am using Vortec Heads on my 350 TPI with SDPC TPi Baseplate, Throttle Body Coolant Bypass, no cat, no egr, no air pump, stock injectors and regulator. I had this engine in a different GTA and it ran perfect with out modifying the chip, I have recently installed in a new GTA due to the unforseen demise of my previous one, and I am too having serious idle issues. I am even using the old computer and prom chip from the previous car. My idle will not steady out for anything. It bounces between 650-1100 rapidly, and only gets worse as the engine gets warmer. I have tried cleaning the IAC, replacing the IAC(For the hell of it), replaced all plennum gaskets, upper and lower, new wires, new distributor, checked for vacuum leaks, and set minimum air/IAC position according to tech article on this site....and none of this has worked at all...I still have the same problem with the same exact symptoms. I had read in a few posts that a bad MAF or MAF Burnoff Relay will cause this, but I'm not sure. Just looking to get some insight from someone whos running a similar setup. Maybee we could help eachother out Thanks

 

Yes, that was what I was thinking, plus he has the fuel pressure cranked. No wonder it's too rich.

If you have a 305, you need to run the right size injectors and get the fuel pressure back to where it should be.