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Old 04-24-2012, 10:43 PM   #1
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dreaded idle issues.

ok,i got a 90 gt pretty much stock.for awhile i would drive when the car is cold and the rpms would hang around 1500 for about 5 seconds then plummett to like almost killing then come back to normal when coming to a stop with the car in neutral and check engine light would flash.it would only do it when cold.performed eec test retrieved code 63.replaced tps sensor and using red lead on my dmm to green wire on new sensor and black lead on dmm to battery ground.got voltage of about .98 volts key on engine off.
now everything seemed fine for a few days then i notice the other morning the check engine light would flash here or there in the rpm range but no symptoms.so i did another eec and once again,code 63.then yesterday i notice i go to put the car in neutral my rpms areound 1200 then raise to around 2000.no check engine light.itll do it for a bit then eventually settle itself down and go back to normal.then itll do it again and stay at 2000 rpms,ill rev the engine and all still 2000 rpms.for the hell of it i killed the car and restarted the idle was normal.
now here i am.kinda wondering where can i start?again.i already did the salt and shaker pin tightening a few months ago and these are the only symptoms.maybe i got a bad tps out the box?i have a motorcraft tps sensor so it isnt some autozone garbage.what do yall think?im sorry i typed so much but im trying to cover all my bases and hope i explained everything as best as possible.thank yall in advance.
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Old 04-24-2012, 11:06 PM   #2
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Re: dreaded idle issues.

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Originally Posted by Nicolosi11480 View Post
ok,i got a 90 gt pretty much stock.for awhile i would drive when the car is cold and the rpms would hang around 1500 for about 5 seconds then plummett to like almost killing then come back to normal when coming to a stop with the car in neutral and check engine light would flash.it would only do it when cold.performed eec test retrieved code 63.replaced tps sensor and using red lead on my dmm to green wire on new sensor and black lead on dmm to battery ground.got voltage of about .98 volts key on engine off.
now everything seemed fine for a few days then i notice the other morning the check engine light would flash here or there in the rpm range but no symptoms.so i did another eec and once again,code 63.then yesterday i notice i go to put the car in neutral my rpms areound 1200 then raise to around 2000.no check engine light.itll do it for a bit then eventually settle itself down and go back to normal.then itll do it again and stay at 2000 rpms,ill rev the engine and all still 2000 rpms.for the hell of it i killed the car and restarted the idle was normal.
now here i am.kinda wondering where can i start?again.i already did the salt and shaker pin tightening a few months ago and these are the only symptoms.maybe i got a bad tps out the box?i have a motorcraft tps sensor so it isnt some autozone garbage.what do yall think?im sorry i typed so much but im trying to cover all my bases and hope i explained everything as best as possible.thank yall in advance.
There are articles in the "Useful Mustang Info" sticky thread that will help you with idle issues.


It is very possible that you recieved a bad TPS. Test it as described in your Chilton's or Haynes manual to see if it is good.


P.S. Use paragraphs and proper capitalization and punctuation. It will make your posts much easier to read and decipher. When it is all ran together like that it is difficult to read and understand.
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Old 04-24-2012, 11:19 PM   #3
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Re: dreaded idle issues.

sorry about that.i am piss poor with grammar lol.
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Old 04-24-2012, 11:27 PM   #4
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Re: dreaded idle issues.

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sorry about that.i am piss poor with grammar lol.
It's no big deal.
I'm just trying to help you get your message across clearly so you can get the help you need.
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Old 04-24-2012, 11:39 PM   #5
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Re: dreaded idle issues.

Thanks for the link im still learning this site so i didnt see it.From what i read in the link,i have already covered my bases so looks like im about to put another tps on and clear my codes and hope for the best.With the new tps im gonna do a voltage sweep and make sure i dont have any dead spots.
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Old 04-25-2012, 01:05 AM   #6
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Re: dreaded idle issues.

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Thanks for the link im still learning this site so i didnt see it.From what i read in the link,i have already covered my bases so looks like im about to put another tps on and clear my codes and hope for the best.With the new tps im gonna do a voltage sweep and make sure i dont have any dead spots.
That would probably be your best bet. Good luck.
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Old 04-26-2012, 05:14 AM   #7
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Quote:
Originally Posted by Trojan Horse

There are articles in the "Useful Mustang Info" sticky thread that will help you with idle issues.

It is very possible that you recieved a bad TPS. Test it as described in your Chilton's or Haynes manual to see if it is good.

P.S. Use paragraphs and proper capitalization and punctuation. It will make your posts much easier to read and decipher. When it is all ran together like that it is difficult to read and understand.
what about the iac Trojan? would replacing or cleaning this really good make a difference?

also the vss coukd that be an issue? just curious cause i was going through the same problems as well?
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Old 04-26-2012, 05:36 AM   #8
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Sorry to jump in on thread...when mine comes to a stop my will idle at 1200 then drop back to 900 and hold real steady. When had dyno tuned, they told me left it that way for reason.(I believe to build vacuum) So could that be controlled in comp.? Just asking... Lots of people with same prob.
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Old 04-26-2012, 05:44 AM   #9
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Quote:
Originally Posted by 87blackonblack

what about the iac Trojan? would replacing or cleaning this really good make a difference?

also the vss coukd that be an issue? just curious cause i was going through the same problems as well?
Yes cleaning the iac could make a noticeable difference.

---------- Post added at 05:44 AM ---------- Previous post was at 05:42 AM ----------

Quote:
Originally Posted by Quball19
Sorry to jump in on thread...when mine comes to a stop my will idle at 1200 then drop back to 900 and hold real steady. When had dyno tuned, they told me left it that way for reason.(I believe to build vacuum) So could that be controlled in comp.? Just asking... Lots of people with same prob.
Yes the ecu controls the idle after the parameters have been set. With my chip in it does that as well, with it out it drops straight to 900.
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Old 04-26-2012, 05:47 AM   #10
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Re: dreaded idle issues.

I had a 93 GT with the same problem, ended up being a fuel vacuum hose and retuning the distrib...Msd distrib
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Old 04-26-2012, 03:42 PM   #11
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I don't mind the idle it's the spit and lack of power between 2000 and 2800
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Old 04-26-2012, 05:58 PM   #12
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Re: dreaded idle issues.

Got new tps on it,cleared code did fine on the way home. So now in the next few days we will see what happens.
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Old 04-26-2012, 07:46 PM   #13
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Re: dreaded idle issues.

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what about the iac Trojan? would replacing or cleaning this really good make a difference?

also the vss coukd that be an issue? just curious cause i was going through the same problems as well?
Yes, it can make quite a difference.


If your 87' Mustang is still speed density, the VSS is not used for idle control.
If it was converted to MAF, then the EEC does use it for idle control and it can cause a surging idle and possible stalling when coming to a stop.
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Old 04-29-2012, 01:28 PM   #14
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Re: dreaded idle issues.

From the sounds of this, the surging is either due to a bad or out of adjustment TPS or a poorly working IAC. Even a bad air temp sensor(screwed into the intake manifold) could cause it, as could a poor throttle adjustment and the aforementioned possibilities.

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If it was converted to MAF, then the EEC does use it for idle control and it can cause a surging idle and possible stalling when coming to a stop.
Hmm... I never knew that. When I replaced my last 5spd and went back to an auto, I used a GM transmission and never noticed anything odd. Granted, mine was already highly modified, but it was a 91 LX 5L(308) and just ran as it had before, only more consistently.

I would've expected the newer AODE used from what I think was 1995(maybe 94 though) till production ended, to be set up as such, but never even considered the non "electronic" version to be the same, though it did have a couple wires when new and stock.
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Old 04-29-2012, 02:21 PM   #15
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Re: dreaded idle issues.

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Hmm... I never knew that. When I replaced my last 5spd and went back to an auto, I used a GM transmission and never noticed anything odd. Granted, mine was already highly modified, but it was a 91 LX 5L(308) and just ran as it had before, only more consistently.

I would've expected the newer AODE used from what I think was 1995(maybe 94 though) till production ended, to be set up as such, but never even considered the non "electronic" version to be the same, though it did have a couple wires when new and stock.
I think the key word in my post is "can".


Maybe by leaving it out of the equation and not having or connecting it, the ECU adjusted to or skipped that parameter?
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Old 04-29-2012, 08:57 PM   #16
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Re: dreaded idle issues.

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I think the key word in my post is "can".
I thought that too, which is why I suspected it didn't happen to mine. I'd just never heard of it with a non electric version.

Quote:
Maybe by leaving it out of the equation and not having or connecting it, the ECU adjusted to or skipped that parameter?
Could be, I suppose. Since I've never had any issue, I honestly don't know why or how it would appear or be handled. I do know, however, how long it takes to burn up an AOD with a Mustang!
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Old 04-29-2012, 09:22 PM   #17
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Re: dreaded idle issues.

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I thought that too, which is why I suspected it didn't happen to mine. I'd just never heard of it with a non electric version.

Could be, I suppose. Since I've never had any issue, I honestly don't know why or how it would appear or be handled. I do know, however, how long it takes to burn up an AOD with a Mustang!
AOD + Mustang + Hot Rodding = Short transmission life.
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Old 04-29-2012, 09:46 PM   #18
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Re: dreaded idle issues.

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AOD + Mustang + Hot Rodding = Short transmission life.
All it took was a former hs gf in the passenger seat saying, "FASTER! FASTER!"
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Old 04-29-2012, 10:01 PM   #19
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Re: dreaded idle issues.

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All it took was a former hs gf in the passenger seat saying, "FASTER! FASTER!"
Yeah, those had a tendency to make you do stupid things to impress them didn't they?
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