Engine in, idles to fast

[rank]

I just got it back together and all back where it belongs,I think, anyhow it runs smooth and quiet but it's idling to fast...1600 toms and when I put it in gear it drops to about 1200 but when I go back to neutral it revs to 3000 then comes back down slowly, any suggestions

 

[rank]

I just got it back together and all back where it belongs,I think, anyhow it runs smooth and quiet but it's idling to fast...1600 toms and when I put it in gear it drops to about 1200 but when I go back to neutral it revs to 3000 then comes back down slowly, any suggestions

Btw, it is an 86 grand national, 3.8 turbo fuel injected

 

[notacarlo]

Vac leak or you did not reset the tps and iac

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[rank]

Vac leak or you did not reset the tps and iac

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[rank]

How do I reset these?

 

[notacarlo]

How do I reset these?

http://www.vortexbuicks-etc.com/iac_adjustment.html

http://www.vortexbuicks-etc.com/tps_adjustment.html

 

[LIL6cyl]

Mine was doing the same thing and my entire plenum was loose....

 

[turbodave231]

Check TPS voltage. Reset to .45-.55Volt at closed throttle. If it is too high, the ecm thinks the throttle is open and the IAC follower routine kicks in and opens the IAC (Idle Air Control)

 

[TurboBob]

cruise control cable pulled too tight will do this also.

 

[TurboBob]

tps volts closed needs to be under about .48 thats where throttle follower starts I think

 

[TurboBob]

How do I reset these?

do you have a way to read data from the ECM (engine computer) ?

Bob

 

[rank]

do you have a way to read data from the ECM (engine computer) ?

Bob

No I don't and I probably need a tuner with a scan master program to tune it. Any idea where I could find someone around Bryan/college station area

 

[rank]

Th

cruise control cable pulled too tight will do this also.

The throttle is closed all the way

 

[earlbrown]

Then you have a post TB vacuum leak.

 

[Sweet6]

I had the same problem Mine was sucking in air from the EGR block off

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[broke]

Did you check or change the pcv valve? This can be the source of a pretty large vacuum leak.

 

[HouTX87]

No I don't and I probably need a tuner with a scan master program to tune it. Any idea where I could find someone around Bryan/college station area

You really need a scanmaster or powerlogger installed in your car. You're about an hour from me. If you want to pay someone you could take it to Century Trans in Richmond but not cheap. Are there any other buick guys in College station? There's quite a few in the Houston area.

 

[notacarlo]

Start the car and start spraying carb cleaner all over every connection, mating surface. Everywhere. The engine stumbles, there's your leak. If its present not under load.

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[TurboDave]

A lot of advice flying around here about vacuum leaks, etc. But we haven't heard a word back from the OP on whether or not the IAC and/or TPS is even properly adjusted. Those two HAVE to be right before poking around elsewhere. Otherwise ya'll are just going to have him chasing his tail.

 

[Sweet6]

I thought he said with the TB closed it idled high

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