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I have an 84 fiero 2.5 Duke manual... Idle EXTREMLY high, New TPS, EGR is closed, no leaks as far as I can tell in other lines to the manifold or TB.

New Thermostat and Temp sensor... Idles way to high to even test! was around 2500 before I changed thermostat and Temp sensor then went to 4000 or higher. stumped

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Posted on Jan 02, 2017

Papa Chan
  • 56 Answers

SOURCE: 1997 buick lasabre custom

It sounds like you have a vacuum leak or intake gaskets leaking. Try this. Start the engine and let it reach the idle it want to go to. Get you a can of Brake Clean and spray it around the intake manifold (it on the top center of the engine, you may have to removed a plastic cover) If the engine idle changes up or down then the intake gaskets are leaking hence your vacuum leak. I hope this will help you.

Posted on Jan 04, 2009

  • 1 Answer

SOURCE: high idle 2500-3000 rpms

you can turn your idle down. i have the same car and it was doing the same thing. i had someone adjust it and it hasnt had a high idle since

Posted on Jan 28, 2009

michigan man
  • 3533 Answers

SOURCE: engine idles rough, misses at 2500-3000 rpm's

i would first check the timing and if that does not fit i would take the cover back off and look at the belt for a bad or missing tooth

Posted on Feb 14, 2009

66 chrgr
  • 1011 Answers

SOURCE: High Idle 2

44 is a lean code throttle body gasket will fix this .code22 is tps sensor but start with gasket

Posted on Mar 15, 2009

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SOURCE: 1989 GMC 2500 5.7L - engine surges and stalls at idle. Loses power at cruising speed.

Wow you have replaced a lot of stuff. Lets go back to the Fuel pump. When you replaced it did you replace the hose between the pump and the sending unit. These are common for splitting. Have you hooked up a fuel pressure gauge to check what pressure you have? It should be real close to 13 psi and should raise to at least 18 or 19 when you pinch off the return line.

Posted on Jun 02, 2009

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Opel Corsa utility 130i. Doesn't want to idle smoothly, dies down reaching stop, traffic light. Checked timing pickup crank pulley, inspected vacuum lines inlet manifold. Could it be a burned valve?

Fuel restriction and vacuum leaks ate what I would suspect first . TPS with bad spots in its travel , dirty injectors, carbon on throttle plates and bore cause idle stalling by restricting airflow at idle . Throttle body gasket leaks, PCV and EGR are vacuum leak possibilities .

Jan 05, 2018 | Opel Cars & Trucks

1 Answer

03 ford escape idles at 1200rpm. cleaned iac replaced bank 2 sensor 1 o2 sensor vacuum lines plugs and intake gaskets cleaned tb iac . runs great 187,400. rpms drop to 850 when ac on. fluids good.

High idle is most often caused by an engine vacuum leak, use a can of carburetor spray and spray it around the intake manifolds (upper and lower), if there is a leak you will hear a change in the idle speed

Oct 05, 2017 | Ford Cars & Trucks

1 Answer

High idle

If you have the 5.0 liter engine or the 5.8 litre there was a problem with the upper intake manifold gasket being cracked and sucked into the intake causing a vacuum leak and the result was high idle. Also a leaking egr will sometimes cause high idle.

Feb 04, 2012 | 1988 Ford F 150

3 Answers

When I start the car it idles high the rpms go up and down

Sounds like you have a dirty EGR (Exhaust Gas Recovery) Valve. There are three things that I think of looking at when someone mentoins uneven running at idle 1) Idle speed air control valve (IAC) - this is small port that is electronically controlled that allows air passed the throttle flap at idle to maintain idle speed. You say you have swapped out your throttle body but it might be good to check that the IAC is clean as most Hondas often fall prey to the same age related faults - spray inlet port with carburettor cleaner and use a bit of old wire to hep clear out any gunk after about 20 minutes. IAC faults generally have the symptom of the car being very reluctant to start but will fire up when given lots of gas. However,as soon as any demand is made on the engine such as power steering or simply engaging the brakes to come to a halt the car will often cutout. 2) Throttle Position Sensor (TPS) tells the engine management system whether the throttle is closed or if open by how much. The symptoms are random often wildly erratic engine idle speeds. 3) The EGR valve - this system is designed to introduce a little exhaust gas back into the inlet manifold to keep the engine ignition temperature low enough to avoid the production of nitrous oxides in the exhaust. This valve looks a bit like an alien space ship about 75mm in diameter. On it top face there is a small vacuum line connector, This vacuum line is connected to the inlet manifold but it may pass through a solenoid valve on the way. This solenoid is for the Engine management system to temporarily prevent the vacuum at engine start up from reaching the EGR thus keeping it closed; the engine temperature is not nearly hot enough, when starting, to cause nitrous oxides in the exhaust. The vacuum introduced to the EGR body pulls on a diaphragm which lifts a valve, immediately beneath to open and this allows a regulated amount of exhaust to pass into the inlet manifold. Connected to the underside of the EGR valve is a metal pipe connected to the exhaust manifold. Faulty EGRs are down to either encrusted carbon deposits holding it open or a broken diaphragm keeping it closed. If closed the engine runs hot and pinks and knocks all over the place. The pipe to to the exhaust manifold can get clogged with carbon deposits and this has the same effect as having a closed valve. If open the car idles unevenly behaving as if there is a leak in the manifold, the open valve is actually just that. Locate the EGR near the throttle body, from the above description you will know it when you see it. Remove the vacuum hose, any electrical connections and undo the retaining bolts and lift clear. Clean everything to like new - the carburettor cleaning spray is again useful here . Applying some suction to the hose connection on the EGR you should see the valve opening and closing. Push a bit of flexible braided (a cut off of handbrake cable is ideal) wire, frayed at the end, to sweep the exhaust connection pipe clean of encrusted carbon. Reinstall everything and fingers crossed job done

May 01, 2010 | 1991 Honda Accord

2 Answers

My 99 suburban idles at 1000 rpm in park with a new TPS at operating temp. What is the factory idle setting? how do I adjust rpm?

There no adjustment for idle, control by computer, TPS reading should be .50 volt's, you could have a vacum leak, check vacum line and check for vacum leak at base of intake manifold.

Jan 21, 2010 | 1999 GMC Suburban

1 Answer

I have an 1989 F150 with the EFI 5.0L engine with a high idle problem. In park it idles between 1500-2000rpm. In drive, it drops to 1000-1500. I've replaced the idle sensor and that didn't help. What else...

Your intake manifold has a leak. Check all the hose connections to see if you have a hose off.
Disconnect the EGR hose and temporarily plug. If it helps it is the EGR.
Take a spray bottle of water and spray around the intake manifold while the engine is running. When you find the leak it will draw in the water and stall the engine or at least affect idle.
Another part is the TPS, throttle position sensor which is on the drivers side and about the size of a cigarette lighter. It has 2 screws and 1 electric plug.
Have Autozone scan your truck for free.

Sep 18, 2009 | 1989 Ford F 150

3 Answers


Low / uneven idle problem can cause by a lot of components.

Dirty air filter

Dirty injectors + o-rings

Vacuum leak at intake manifold and vacuum hose.

Bad Idle Air Control Motor (IAC)

Low compression (170 psi + is OK)

Start cleaning and repair these trouble spots and see is there any improvement.


For more advance DIY'er then you may try this.

Use a can of Berryman carburetor clean to locate the vacuum leak.


This is a 20-30 minutes job.

Vacuum leaks can occur in following locations.

Intake manifold AND/OR vacuum lines.

Intake manifold is not accessible unless the engine head if off.

You can still check the potential leak by spraying some Berryman near the intake manifold.

Listen for rpm increase after you introduce the Berryman (FUEL) at idle.

Do the same starting from the brake booster unit (the round unit) on the drive side fire all.

Carefully listen for increase of RPM right after to spray the Berryman to the potential vacuum spot.

Get a friend to HEAR the ROM increase or monitor for RPM on the tech.

DO NOT AIM the Berryman into any heat source.

PLEASE RATE my answer if it is useful to you.

Aug 20, 2009 | 1995 GMC Suburban

2 Answers

2.5l iron duke will not idle

Scan again & check reading of the ECT sensor,coolent sensor as it may be reading to cold for present temp & just dumping fuel as it is seeing -30c all the time.I as well own a iron duke(1987)

Apr 06, 2009 | 1988 Chevrolet S-10

2 Answers

High Idle 2

I would look at the codes,, jumper the two upper connector holes in the diagnostic link with a paperclip,, turn the key on, and read the blinks of the check engine light,, first will come 3 12 codes then any error codes. If you get a repair manual for that vehicle it will tell you how to perform these tests.

Mar 11, 2009 | 1985 Pontiac Firebird

1 Answer

1995 Ford Bronco 172 EGO not switching lean bank1- jerks when run

Have u checked for vacuum leaks or poss leaking EGR valve? use carb spray around the upper intake manifold where it bolts to the lower manifold, spray vacuum lines where they are connected to the engine vacuum ports, the idle speed will change if u hit a leak, as far as the EGR valve goes see if it gets hot at idle, if it does it is leaking, if all checks ok replace the O2 sensor, but i suspect u will find a leak at the upper intake plenum.

Dec 06, 2008 | 1995 Ford Bronco

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