Brianbajnuth

Ok so I have a 87 gta trans am it starts up and runs but at first start it idles rough but when the car warms up it's ok runs fine. I do not have o2 sensors and I do not have a egr valve. I didn't take those things out I bought the car like that. The fuel pressure is at 50 with the vacuum line connected. I changed spark plugs but not the rotor. I have a msd spark box too.

Brianbajnuth

Also if the o2 sensors were disconnected wouldn't the engine light be on? Can I add them back if that would change the idle

Oddie65

Have you checked you IAC valve? If its dirty or not functioning properly, it can cause all sorts of hell with the idle. As far as the check engine light goes, yes I would think the light would illuminate. It's possible that the bulb is just burnt out, but I've also heard of people tuning the memcal's so they no longer throw a code with something like o2 sensors disconnected. If I were you, and theres still a bung for the sensor, I'd put em on. There are numerous articles on here and from a google search on how to check/reset your IAC. I would start there, its simple and pretty much free.

Brianbajnuth

Thanks so much for the reply.
I took out the idle air control valve and I plug led it in and turned the car on the ON position and the idle air control valve pintle didn't move. I felt a little vibration but it didn't move could that be the problem.
And about the o2 sensor the bung it not there it has a full exhaust

Brianbajnuth

Anyone else with ideas?

Oddie65

Sorry for the late reply bud, but yes if the pintle didn't move at all then your IAC is faulty. Without an 02 sensor it still may not run completely perfect, since that helps determine your a/f ratio, but as far as a rough idle the IAC will have a huge impact.