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I have been trying to fix my idle issue for a very long time.

 

The engine was rebuilt before I bought the car and it's still pretty fresh.

 

Can anyone take a picture of their throttle plate stop screw? I am worried that someone has adjusted mine. I am also wondering if the TPS is set correctly. I messed with the today. Didn't seem to help anything

 

I have checked all the vacuum lines a million times

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Did you check your break booster to see if its has a vacume leak just clamp the line closed iv3 had the rubber gromit go bad too and creat a vacume leak

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trying to guess what engine and fuel system in use :(

 

if it is mpfi, the little round seals the injector sits in can leak air causing a rough idle, afecting speed, as can any air leak which peeps suggest spra y a little wet spray oil about gaskets etc one at a time to se if something pinpoints

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I guess you would have had to read his past posts to know or just watch the vid

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Maybe i should have watched the vid thats no vacume leak sounds like a sensor check your grounds first then unplug one sensor at a time im thinking temp sensor or o2 sensor or something connected with them just guessing

 

Oh ya a bad map/maf sensor would cause that also a leak in the intake boot a leaking crank case venting system could be adding extra airinto the system

Dose it do it all the time or just when cold or warm

Edited by ferp420

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That is weird. The way it varies. Never had one doing that. It is a spfi fuel system. At one point, it does sound like there may be a vacuum leak in the video. But those I've not seen make the surging, just the thin hissing sound.

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The surging is the computer trying to work out the air fuel ratios going from rich to lean to rich to lean the sensors arent giving the computer the corect info if you take the sensor out of the system the computer is saposed to go in to closed loop mode and runs rich for safty reasons so unplug one sensor at a time and run it it may be 2 bad sensors or could be some corostion or a bad ground its very commin

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I was thinking maybe o2 or temp sensor also. I may try replacing them both. I have capped off every vacuum. Including the PCV system. I've sprayed all over the intake gaskets and throttle body to see if they are leaking.

 

Can any of you with SPFI take a picture of you throttle stop screw for me? I'dike to make sure mine hasn't been messed with.

 

I noticed that someone ran a new Tan wire for the IACV at some point. Maybe they thought that was the issue. I can see the IACV moving when I remove the rubber hose.

 

I'll get another video or 2. Under WOT the engine has plenty of power. It's actually the strongest ea82 I've had

Edited by TheGageinator

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Vacuum leaks don`t just come only from vacuum lines.

 

Might be an unmetered air leak between the MAF and throttle body instead.

Would be the same symptoms.

Check the big intake hose and everything attached to it for leaks.

 

That hissing DOES sound like a vacuum leak though.

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It is not misadjustment of the throttle stop.

 

What happens if you attempt to increase idle speed w/the idle speed screw?(w/isc DISCONNECTED)

 

What is the ECU LED doing?

 

What is the O2 sensor voltage?

 

I`d feed it some propane to see if it smooths out.

Edited by naru

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Changing That setting wont do anything for you if you back it off all.the way it shouldent change anything screwing it in will only make it do the same thing faster its only there to stop ware on the throtle body and flapper i would take a few pics anyway but my roo is 2000 miles away right now

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The o2 sensor is not used for anything until the engine is at normal operating temperature. Then only fine tuning of the mix for clean burning.

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It is not misadjustment of the throttle stop.

 

What happens if you attempt to increase idle speed w/the idle speed screw?(w/isc DISCONNECTED)

 

What is the ECU LED doing?

 

What is the O2 sensor voltage?

 

I`d feed it some propane to see if it smooths out.

No check engine lights, is there another ECU LED I should know about? I can check the 02 sensor voltage soon. I think I also have another sensor somewhere I can try.

 

OK, that makes sense about the throttle stop screw.

 

I did remove and inspect the TPS to make sure it was OK. It checked out, and I reset it properly I think.

 

How would I give nut propane, through a vacuum line?

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The ECU LED is view able through a hole in the ECU case.  The plastic trim panel under the steering column must be removed to be able to see that hole.

 

That is where you read any codes.  Usually, the check engine light will be on if there are any codes - especially if they are related to a malfunction that is happening while you are reading the LED blinks.

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While it's idling and surging, clamp the IAC tube closed and see if the idle surge stops.

 

If that's the case, then your IAC is faulty, and "blowing in the wind" so to speak.  Unable to hold a set opening,

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It is not misadjustment of the throttle stop.

 

What happens if you attempt to increase idle speed w/the idle speed screw?(w/isc DISCONNECTED)

 

What is the ECU LED doing?

 

What is the O2 sensor voltage?

 

I`d feed it some propane to see if it smooths out.

Just make sure no stray sparks about if you do the propane trick or you will have more problems

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so, can you disconnect idle air control device for purposes of diagnosis? See if any changes.

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Yes, pull the hose off, see what changes while idling.  It should still idle, but not the same.

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