EFI idle issues

[jayh]

I have a Factory Five with a 302 with Trick Flow Top End Kit. When the car warms up the idle surges up and down to the point that occasionally it will die when approaching or stopped at a light.
Don't know if its a computer issue or a component issue, Throttle body, mass air flow sensor, ect
any help appreciated if you have experienced similar issues
Thanks

[eschaider]

This sounds like a potential vacuum leak or two other possibilities, the IAC motor or you TPS zero.

I would do the vacuum leak check first. If you don't have a smoke machine use some starter fluid around the potential leak point locations. If idle speed changes you found your problem. Now seal up the leak

I am not sure how your EFI system tells you to set your IAC. This approach is usually a workable solution.

With the engine at operating temperature disconnect the IAC motor and adjust the throttle to give you about 100 rpm or so below your target idle rpm. Shut off and reconnect the IAC motor. When you restart the engine it should idle smoothly at your program tune rpm.

Some fuel injection systems will be easier to do this to if you change your tune idle down 100 rpm also. If you need to go this route then you will have to reset idle in the tune to your old target before restarting after reconnecting the IAC motor.

If your TPS is not zeroed it will report a different throttle opening than you actually have and then the ECU will fuel for that air mass even though you don't have it. The result could produce a hunting idle also.


Ed

[spdbrake]

Have you got a OBTII code reader? (about $50 at Pep boys etc...)
If the IAC (Idle Air Control Valve) is sticking or the vac source hose has a leak you may have a 0505 code.
([ame]https://www.youtube.com/watch?v=6TZK_RqjjD8[/ame])
I'd also clean the MAF (use the right cleaner though)
([ame]https://www.youtube.com/watch?v=cBJnp8Q29JI[/ame])

[jayh]

Thanks for your input....I'll let you know what works