Really high idle

Started by manifoldsrme, November 10, 2009, 05:10:03 PM

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manifoldsrme

So driving home today the TGP started idleing really high, would not come down. Was surging as well like it was goverend or something. Anyone want to take a stab at this one? I looked for obvious vaccum leaks but it was dark so I need to look again when it is light. It ran perfect the other day and this mornng. It just started doing it.
1990 TGP

Jonpro03

I had a leaking uim gasket when that happened to me

1997 Grand Prix GTP coupe topswap
1990 Turbo Grand Prix Black/Tan Interior 15.05 1/4mile

killinprixs

idling high and surging betweet 2000-2500?  sounds like TPS plug wiggled loose but the check engine light would pop on and throw code 22.   If thats not it check Idle air control sensor or replace and do idle relearn.... that is if its not a simple vacuum leak... also maybe bad PCV valve or cracked hose connecting it under the upper intake manifold..  it would have to be a pretty big vaccuum leak to idle that high and surge tho.

manifoldsrme

#3
So after close inspection I found a cracked vacuum hose, but that had nothing to do with the high idle. The cruise control cable was frozen up. I remember I had tried to set the cruise on the way home when I was on the freeway, and it just stayed at that rpm, about 2900. I unhooked the cable for now, replaced the hose and damn does it run good. Breezed through emissions and has real plates now instead of temps. Idles perfect, and the hesitation and occasional missing are gone. It shifts much smoother than before.

It has come a long ways from the day it came off the hauler at my house with 5 year old gas, dying constantlty with no brakes!  :icon_cool: It still needs new tires badly as the ones on it are shot from sitting. They vibrate so much my wife keeps taking it on short trips...... :icon_lol: The speedometer stopped working, and it needs some pieces replaced in the interior.

I have another car (wifes firebird) getting painted ahead of it, so it wont be at any shows next year with my IROC. But I am definately liking the car so far. Hopefully I have worked out all the issues and my questions can be restoration related now.

First day running sweet and legal.


1990 TGP

TGP Nick

Nick
1989 Pontiac Turbo Grand Prix- LG5 - 4T60HD
2008 Ford Ranger XLT- 2.3 DOHC I-4 - 5MT
2012 Nissan Altima SR coupe- 3.5 V6 - 6MT

mfewtrail

Those quick/easy fixes are always nice. ;) Is just the speedometer on the instrument panel just not working or do you now have no reading on the head's up display as well?
'93 SE, '90 Black/tan TGP, & '90 Red/tan TGP

manifoldsrme

The heads up reads "0" and the speedometer doesn't move.
1990 TGP

killinprixs

good for you man, that was a little less complicated than i made it!  I remember the cruise control stuck on my car one day right at the rev limiter...scared the crap outa me!

mfewtrail

Quote from: manifoldsrme on November 15, 2009, 06:25:49 AM
The heads up reads "0" and the speedometer doesn't move.

You might have a dead vehicle speed sensor, bad wiring to it, or it isn't plugged in. Do you know if the odometer is logging mileage or is it inoperative as well?
'93 SE, '90 Black/tan TGP, & '90 Red/tan TGP

manifoldsrme

Looks like the odometer is not working as well. I hadn't noticed until you mentioned it.
1990 TGP

TGP Nick

There is a wire next to the odometer inside the gauge cluster that can come unplugged, or I've seen a little retaining clip that holds the odometer worm gears on pop off and cause it to not work... More than likely a speed sensor/wiring issue though.
Nick
1989 Pontiac Turbo Grand Prix- LG5 - 4T60HD
2008 Ford Ranger XLT- 2.3 DOHC I-4 - 5MT
2012 Nissan Altima SR coupe- 3.5 V6 - 6MT

mfewtrail

Quote from: manifoldsrme on November 16, 2009, 10:45:14 AM
Looks like the odometer is not working as well. I hadn't noticed until you mentioned it.

Since both are not working, it should be related to the VSS(vehicle speed sensor) or the wiring to it. The VSS is located near subframe height approximately under where the alternator sits. I can post a trouble shooting chart for you from the factory service manual if you need it.
'93 SE, '90 Black/tan TGP, & '90 Red/tan TGP

manifoldsrme

Anything will help. Is there a picture of the VSS you can post showing it's location?
1990 TGP

mfewtrail

Quote from: manifoldsrme on November 17, 2009, 08:28:23 PM
Anything will help. Is there a picture of the VSS you can post showing it's location?

Here are some large pictures of the VSS troubleshooting charts & I also included the cluster wiring diagrams just in case you need those. One of the pictures is a component location view, the VSS is shown in the upper right hand corner on that page. Once you click on a photo, click on the picture again for the full sized view. If you can't make out the colors or writing on the wiring diagrams, let me know and I'll upload larger versions.

http://s44.photobucket.com/albums/f14/platjblser/TGP%20-%20VSS%20and%20Cluster/
'93 SE, '90 Black/tan TGP, & '90 Red/tan TGP

manifoldsrme

I ran out of time and put all the toys away for the winter. I will put new tires on the TGP and address the inoperative VSS in the spring. I will resurect this post then. Time for a few months with no car projects.
1990 TGP