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Having idling problem on 1990 buick lesabre limited when in park or neutral the rpms go up from 1500 to 2500 sometimes 3000 in the past i replaced the tps, idle control valve, cleaned the mass air flow censor and cleaned up the throttle body and replaced the gasket anyone got any suggestions?

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  • 52 Answers

Check for a vacuum leak. You may need to adjust the IAC(idle air control). If the power brakes are also very hard then its a vacuum leak.

Posted on Jan 01, 2014


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Posted on Jan 02, 2017

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SOURCE: rough idle on 1990 saab 900 convertible, 16V

Because the car has adaptive technology, it may take a while to reset and adjust to the new, cleaner and better conditions than those to which it had previously adapted.

Did you change the cap and rotor? if the plugs needed replacement, likely they do too

Possible other causes include:

loose or corroded connections to any electrical component you disturbed (make a checklist and tick them all off as you check them);

mis-reinstallation of any F.I. part disturbed(checklist again)

obstructed water flow through the AIC valve;

improper voltage output from the AIC valve (for LH 2.4 systems, should output 8 volt at idle, dropping as load increases; for LH 2.4.2 system output 7 volt at idle etc; testing between terminals)33 and 17 at disconnected LH connector;

possible problem with MAF.

Hope this helps


Posted on May 30, 2009

  • 11896 Answers

SOURCE: 1999 pontiac grand am 4 cylinder rough idle, rpms fluxuates

Most likely your throttle position sensor is faulty. You could have a vacuum leak as well. Most probable cause is a bad sensor. Is your check engine light on? Have you checked your engine codes? You can go to and register for full free online repair manual.

Posted on Sep 14, 2009

Testimonial: "the check engine light had been on but we unplugged the battery yesterday for a couple of hours and put it back in and the light isn't on anymore. "

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SOURCE: 97 buick lesabre 3.8 Idles rough and stalls out.

ignition system not operating properly ,or intake air leak ...crank engine get a can of staring fluid spray around the intake if the motor idles up you got a leak hope this helps

Posted on May 08, 2010

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96 buick lesabre ...already posted a question,,but wanted to add that it seems like an air leak,,replaced aic valve,,no change,,the rpms raise to over 3000 and lowers to 800 on and off till car stals,,when...

Trying to guess your way through a repair never works , Having a qualified Technicain with the proper diagnostic test equipment an knowledge does . It could be any number of thing's causing this problem . Looking at scan data ,checking IAC control by the PCM ,MAF sensor data . fuel trims ,EGR etc...

009 Idle Speed Problems Scan Data for EGR
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Nov 03, 2017 | 1996 Buick LeSabre

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1990 Buick Lesabre Limited. Has 140000 miles on it. Car shakes and is slow to accelerate. Car does not shake in neutral or park. This varies by trip. Sometimes it runs better than ever, other times it...

First thing to do is replace spark plugs and ignition wires.

It will usually clear this up and if u take it to a garage they will do that anyway and charge you dearly.

If you need further help, reach me via phone at

Mar 03, 2018 | Cars & Trucks

1 Answer

I have a 00 buick century. i cannot get it to go past 2800 rpms in any gear..driving or at idle have changed icm. sounds like rev limiter kicks on. this happens when your driving as well

Thinking there is a rev limiter on that car,designed to work only in park and neutral
Sounds like maybe it's staying on,
My first thought would be the neutral saftey switch on the ******.

Sep 16, 2011 | 2000 Buick LeSabre

1 Answer

My 1997 lesabre runs fine until Im at a stop then it idles ruff it is less sever when in park but bad when im stop using the brakes

Could be the Idle Air Control if so equipped. The smoother idle is because when in neutral or park, there is no drag on the engine from the transmission.

Aug 13, 2009 | 1997 Buick LeSabre

1 Answer

Car drops out at 2700 rpm and sputters

There is a rev limiter in these cars that disallows over revving in park or neutral. Does it climb past 2700 under hard acceleration?

Jun 01, 2009 | 1990 Ford Thunderbird

1 Answer

I have a 2003 Lincoln LS and it wont go over 3000 rpms

this car has a limiter on it so the engine wont go over 3000 rpms in park or neutral

Apr 19, 2009 | 2003 Lincoln LS

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1990 Buick Lesabre keeps stalling

Check ecm for part number 1228253. If it has this number in it replace it with a 16198264. Gm had trouble with that ecm for a cutting off problem. Mine would stall driving down the road and when I would put it neutral it would start back up and not have any trouble for the rest of the day. You must set the tps with a volt meter or scan tool.

Apr 18, 2009 | 1990 Buick LeSabre

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