1990 gmc jimmy high idle - Great Lakes 4x4. The largest offroad forum in the Midwest

Go Back   Great Lakes 4x4. The largest offroad forum in the Midwest > 4x4 Talk > Chevy Tech
GL4x4 Live! GL4x4 Casino

greatlakes4x4.com is the premier Great Lakes 4x4 Forum on the internet. Registered Users do not see the above ads.
Search
Reply
 
Thread Tools Search this Thread
Old May 17th, 2013, 07:53 AM   #1
sanman
Senior Member
 
sanman's Avatar
 
Join Date: 03-14-09
Location: nashville mi
Posts: 1,572
iTrader: (25)
Mentioned: 0 Post(s)
Default 1990 gmc jimmy high idle

Has a tbi 350 with a 700 r4 tran's has high idle while moving shifter in and out of gear . It will idle about 1500 and does not do it in park only when you move the shifter and no foot on the brake does it as soon as you move the shifter. If you shut it of and restart it usually it 's fine any ideas?

Last edited by sanman; May 17th, 2013 at 07:57 AM.
sanman is online now   Reply With Quote
Sponsored Links
Advertisement
 
Old May 17th, 2013, 07:50 PM   #2
Iggy
Senior Member
 
Iggy's Avatar
 
Join Date: 01-02-12
Location: Traverse City, MI
Posts: 130
iTrader: (7)
Mentioned: 0 Post(s)
Default

Check for a vacuum leak. Low vacuum readings causes the computer to add more fuel which increases rpm.
Iggy is offline   Reply With Quote
Old May 17th, 2013, 08:54 PM   #3
sanman
Senior Member
 
sanman's Avatar
 
Join Date: 03-14-09
Location: nashville mi
Posts: 1,572
iTrader: (25)
Mentioned: 0 Post(s)
Default

I have been looking so far have found nothing, i was thinking brake booster but it does not do it all the time.
sanman is online now   Reply With Quote
Old May 19th, 2013, 06:15 PM   #4
sanman
Senior Member
 
sanman's Avatar
 
Join Date: 03-14-09
Location: nashville mi
Posts: 1,572
iTrader: (25)
Mentioned: 0 Post(s)
Default

Any other idea's just move the shifter from park to revese with no foot on the brake and you don't have to engage all the way in to gear and goes to1500 rpm
sanman is online now   Reply With Quote
Old May 20th, 2013, 08:10 AM   #5
Iggy
Senior Member
 
Iggy's Avatar
 
Join Date: 01-02-12
Location: Traverse City, MI
Posts: 130
iTrader: (7)
Mentioned: 0 Post(s)
Default

I would keep looking for a vacuum leak. It could be caused by a dried out intake gasket (I had that happen on a couple of TBI engines), the base gasket of the TBI unit, any of the hoses or even internally in the TBI unit (the throttle shafts are known to wear and leak).

Last edited by Iggy; May 21st, 2013 at 09:59 AM.
Iggy is offline   Reply With Quote
Old May 20th, 2013, 03:49 PM   #6
sanman
Senior Member
 
sanman's Avatar
 
Join Date: 03-14-09
Location: nashville mi
Posts: 1,572
iTrader: (25)
Mentioned: 0 Post(s)
Default

Intake gasket's are newer all hose's look good and sprayed carb cleaner around the tbi with no change, does not do it all the time would the nss have any effect on the idle?
sanman is online now   Reply With Quote
Old May 21st, 2013, 09:56 AM   #7
Iggy
Senior Member
 
Iggy's Avatar
 
Join Date: 01-02-12
Location: Traverse City, MI
Posts: 130
iTrader: (7)
Mentioned: 0 Post(s)
Default

If not vacuum, then check the IAC (idle air control) Valve - the computer uses that to control the idle speed. May also want to make sure the TPS (Throtle Position Sensor) is working correctly - should read .525 @ idle. Also, check timing (computer disconnected) to make sure it is not too far advanced.

Last edited by Iggy; May 21st, 2013 at 10:00 AM.
Iggy is offline   Reply With Quote
Old June 1st, 2013, 05:41 PM   #8
cerial
Senior Member
 
cerial's Avatar
 
Join Date: 09-06-08
Location: Caledonia,MI
Posts: 1,745
iTrader: (3)
Mentioned: 1 Post(s)
Default

Ah those damn plastic hoses can be tricky. Carb cleaner won't tell you much. You need to pull the hose plug one end and then blow into the other to really check. I would just replace them at this point because they do crack. Careful when pulling them by wiggling the rubber fitting off or the plastic hose will break for sure. If your dead set on reusing them shoot some cleaner down them to clean out all the oil residue.

Pull the iac then push the plunger in a few times and if it sticks at any point it should be replaced. You can shoot it with carb cleaner then reinstall it until you can get to the parts store. The part is real cheap though.

The TPS is the same way pull it, clean it, and see if it helps. It is also a cheap part.

If you are careful when removing them you can reuse the gaskets by spraying a bit of copper seal on them for a temporary seal to get to the parts store.

I have used wet cardboard before to also make a good seal in a bind.


Check the connections at the idc, tps, and at the injectors for bad wiring. Everything should be tight. Loose connections can make the computer do interesting things.

If you are still using the stock air cleaner with the heat riser try running with the air cleaner off. I had a heat riser stick before and it had me pulling my hair out trying to figure out why I had a high idle.
cerial is offline   Reply With Quote
Reply
Great Lakes 4x4. The largest offroad forum in the Midwest > 4x4 Talk > Chevy Tech

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 04:33 PM.


Powered by: vBulletin, Copyright 2000 - 2012, Jelsoft Enterprises Ltd.
User Alert System provided by Advanced User Tagging (Lite) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd. Runs best on HiVelocity Hosting.
Page generated in 0.24630 seconds with 44 queries