1993 5.7 tbi not idling properly and holding shifts

[Dylly]

This is my 1993 short box, reg cab, 2wd toy truck that I only drive in the summers. So I took the truck out for the first time a day ago... ran fine, shifted fine until i fired it up this morning ...

Wants to idle at ~1200rpm... when it tries to idle down, it attempts to die and surges up to ~1200rpm again ... Changed the idle air control (IAC) sensor out... same thing still ...

Took it out for a drive and it refuses to shift unless you let your foot off the throttle... Held it at 2000rpm and wouldn't shift out of first without letting off the throttle.

Could these two symptoms be related? and/or what could my problem be?

 

[THEFERMANATOR]

Sounds like a throttle position sensor or possibly a coolant temp sensor.

 

[Dylly]

Would the throttle position sensor cause both shifting and idling problems?

The coolant seems to be registering fine on the dash... could the sensor be cooked anyway?

 

[WarWagon]

ECM and gauge coolant temp sensors are different. TPS is a maintenance item anyway. You can test it with a voltmeter to be sure.

 

[Dylly]

Well good news! Changed the TPS and it shifts and idles like it used to.... I guess the TPS operates how it idles and is used to determine shift parameters by the ECM.

Either way... Its nice when the first suggestion works.

Thanks a lot!

 

[btfarm]

Glad to hear you're back in business!:thumbsup: