5.0 Idle Problems

[Mac99gt]

I recently purchased a 90 lx with a rebuilt 5.0. The problem I have is with cold start-up. It will not idle at all until it is warm. Here are some details about the motor. 306 with E-303 cam, Gt-40 intake, stock heads, smog pump removed, stock fuel system and ecm. I have installed one of thoes adjustable idle air plated and that helped to smooth out the idle but did not help it when its cold. It almost seems like it is getting too much fuel at cold start??? Help.

 

[ponycar17]

A lot of cars with E-cams, or any other wilder cam, does that. If it's as simple as erratic airflow, and low vacuum caused by that cam, you can try clocking your mass air meter to different positions, to see if that helps. Clocking the meter, so that the sensor is moved clockwise, looking from the front of the engine, might help a little. You can buy one of Pro-M's toys to electrically manipulate the MAF voltage as well.

How about your air filter? You aren't running a cone filter under the hood, are you?... If so, fan wash can cause that erratic idle...

But again, if this isn't your problem, I'm not helping at all...

 

[NYC LSC]

oops

 

[NYC LSC]

I have the same problem with mine. I've changed the ACT, ECT & IAC sensors, O2 sensors, clocked the C&L and even re-adjusted minimum idle and the TPS and it still does it.

Beat the hell outta me what's going on. lol

 

[Mac99gt]

I have a fenderwell filter. Should I buy an aftermarket maf. Why does it go away when it warms up. Acts like a carbureated engine.

 

[NYC LSC]

I have an aftermarket MAF and it still does it. I was told that the car looks at the ACT and ECT sensors during open loop operation and figured that would be my problem. Guess not.

As for why it runs better when warmed up after a few minutes - is it's running mainly off the O2 sensors. That's why I was sure the ECT sensor on my car was shot.

Sorry I'm really of no help here, but you're not alone.