3.4L Engine Idle

[Mstg007]

I have a 94 3.4L. Today driving into work. I was at a stop light and the idle (while braked) was 1.5 RPM. Usually its under 1 RPM. Then, I went to put it into park and it was revin around 2.5 RPMs. I turned off the engine and then back on and it went back to normal (Under 1 RPM). Any ideas on this? Sensor or something else?

 

Thanks for any help guys!

[White93z34]

Generally one of 3 things

 

Bad IAC

Broken or leaking brake booster vacuum hose

Cracked intake gasket

 

But of course, check vacuum lines first.

[Galaxie500XL]

There's a few possibilities, but mine did this twice in the 7 years I owned it...in both cases, it turned out to be a bad throttle position sensor. The reason it happened twice was the store brand sensor went bad within a few weeks. Bought an OEM sensor from Rockauto, and drove for years after that with no further issues. 

[Mstg007]

Well I guess I can try that. Seems cheap enough to try. Kinda of think of it. I might have had this happen along time ago (Similar to what you had happen but I never did change anything,)

 

http://www.rockauto.com/en/catalog/oldsmobile,1994,cutlass+supreme,3.4l+v6,1223367,fuel+&+air,throttle+position+sensor+(tps),5136

[Imp558]

But of course, check vacuum lines first.

[Galaxie500XL]

 

But of course, check vacuum lines first.

 

Especially the power brake booster hose...they get puny after a few decades---and they're often overlooked.

 

EDIT:  And the PCV hoses...LQ1's have a pretty pathetic method of attaching the hoses to the PCV valve itself.

Edited June 29, 2017 by Galaxie500XL

['93RegalGS3800]

EDIT:  And the PCV hoses...LQ1's have a pretty pathetic method of attaching the hoses to the PCV valve itself.

 

Let me tell you of a accidental PCV horror story I had with the Regal back in 2012...