i need help with my 91 formula. I replaced my tbi 305 with a 89 tpi 350. Everything was changed and car ran fine with open headers. But now the engine runs bad. When you give it gas it falls flat, if you rap the gas it will quit. I replaced plugs, wires, cap, rotor and the ecm. Went over the timeing and fireing order. I was told it might be the IAC but dont know much about this. I need help here. Does something need to be reset. Im lost and come to a stand still.

 

Have you checked for codes yet?

 

If it ran fine with open headers I'm assuming you are now running through an exhaust system? If so, I would check for a plugged converter or restricted exhaust. Take the pipes off of the headers or disconnect the exhaust at the converter and run it.

 

if you are running through exhaust, mufflers what ever... i am betting some stupid company trying to be cute left oh i dont know a warranty card or something stuck in the CAT.... how many RPMS can you get out of it? i am betting about 2800-3000

 

I havnt checked for codes yet. yes im running through a stock 2 1/2 to 3in exhaust. Im getting a poping nosie out of the muffler. The CATS have been removed, now just a 2 1/2 pipe from the y pipe. i order a new muffler but will try running it unhooked. This all started when my farh told me the fireing oder was wrong. so i went over the plugs then started messing with the dist.

 

when its running it will sit and idel fine. Now as soon as you touch the gas it wants to die but if you give it steady gas it will rev up to 5 to 6k rpm. it sounds like it has a flat spot in the gas.

 

well what did he say was wrong with the firing order? what did you change to fix it...

 

not really watching what i was doing, i removed all the wires from the cap and rewired them. He said it looked like it was running rough, shakeing a bit. This was right after the exhaust was done but a few leaks.

 

Sounds like you need to start by checking your basics. First off, make sure that you do have the firing order correct, and get the timing set properly. Once that's done, go to the tech articles here on the site and read up on setting the IAC and adjusting the TPS voltage. Setting the IAC and TPS on a TPI motor is essentially the same thing as dialing in the idle and mixture settings on a carbureted motor. In fact, the TPS voltage is basically your accelerator pump shot adjustment on a TPI. If it's not set correctly, you'll have a flat spot when you mash the gas.

 

thank you Pat, that sounds like its the right thing to try. it sucks being new to thins kind of system.

 

ok. i checked the TPS and it was at 0.61 steady. opened it to wide open and it was at 4.45. ran it slowly to wide open to 4.45 with no jumps or sticks. The IAC has never been messed with the cap is still there. not sure how to reset it, if i have to or not. i took it out and it seemed to be ok, just alittle black build up on the end of the triangle point. i only got to start it once before it started raining. it ran a bit better not so much of a flat spotin the gas. could the IAC be the rest of the prob? Thanxs again Pat for pointing me the right way.

 

It's not the IAC. As soon as you open the throttle, the IAC is out of the picture. forget that, and move on.

Sounds like a fuel delivery problem... adding air (opening the throttle) kills it by leaning it out.

What's the fuel pressure AT THE INSTANT IT DIES? Not sitting in the driveway runing fine at idle; but AT THE MOMENT OF MALFUNCTION?