73-87chevytrucks.com

73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: jsmith392003 on May 29, 2009, 06:57:36 am

Title: HIGH IDLE UNTIL FULL WARM
Post by: jsmith392003 on May 29, 2009, 06:57:36 am

I have a 1987 with a 355 c.i. and it is throttle body fuel injection. It does not want to idle down until it is at full operating temperature. I thought maybe a lazy O2 sensor but that did nothing. Any idea's on how to get this to idle down before 10 minutes of running?

Title: Re: HIGH IDLE UNTIL FULL WARM
Post by: VileZambonie on May 29, 2009, 07:47:15 am

The computer doesn't even look at the O2 sensor when the engine is cold. The first thing I would check is for vacuum leaks. Check the base of the tbi unit. The gasket can get sucked in. Does the check engine light come on? Do you have access to a scan tool?

Title: Re: HIGH IDLE UNTIL FULL WARM
Post by: jsmith392003 on May 29, 2009, 08:47:45 am

Replaced the throttle body gasket with new. There is no check engine lamp. I do have access to a scan tool.

Title: Re: HIGH IDLE UNTIL FULL WARM
Post by: VileZambonie on May 29, 2009, 10:18:39 am

There is no check engine lamp as in the bulb has been removed or does it come on with the bulb check and go out? If you have access to a scan tool report back any stored DTC's and your datastream. IAC counts, ECT, TPS voltage, Map Voltage, Fuel integrator and block learn while it's idling high would be most beneficial.