TPS vs IAC... WTF?!?!? REALLY?!?!?!?

UltimateSVT

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IAC has been replaced on my 93 & now its worst! The car wants to shut off & then accelerates to 2,000 rpm's. It comes back down to 1,000 rpm's then starts shuttering again. It won't shift from 2nd gear & the transmission mechanic showed me the OBD1 reader stating that the TPS sensor is bad! Is the TPS(Throttle positioning sensor) the same as the IAC?

My frustration from my 93 grows deeper! I'm spending cash on the car to get it ready for Palm Harbor & I 'm also trying to save up enough so I can paint the 97 that I need to sell in order to pay for the CE I just got but each time it seems more difficult! I'M SO PISSED!!!! :mad: :mad: :mad:
 

Tiltedhalo

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TPS, throttle position sensor is on the throttle body and tell the ECU throttle position. IAC idle air control actually controls the cars idle. I would think with a jumping and variable idle the TPS is bad.
 

Big Mike

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TPS is near the IAC, behind the TB IIRC. Try disconnecting it and if you get improvement (it will not be right but bettter) you know you are good in replacing it.
 

Right on the Mark

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IF your buddy says he watched the TPS function and its wacked its wacked. They are just a potentiometer, fancy word for dimmer switch. Even after you replace it you should make sure it reads around .97 volts at closed throttle ,over 1 volt and it tells to enrich. This is checked key on engine off. Read volts on green wire if I remember from old days. You will notice tps bolt holes are slotted for some movement to bring in this spec. One funny thing about tps is it acts like a mini throttle. If you where to start car with tps in your hand then manually rotate the inside of the tps the engine will rev. Just my 2 cents.
 

BAD97LSC

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alex take the throttle body off, four 8 mm bolts, the tps in on the throttle body facing the iac if i recall, its held in with 2 phillips screws and you will not be able to take them off with the throttle body on the car, they have loctite on them from the factory and its very easy to strip the heads out, so use a bigger phillips and push real hard when breaking loose, you might want to lock the t.b in a vise so you can really push on them screws, new tps i think is around 18-20 bucks roughly. get a new throttle body gasket at the same time, 2.99 for felpro.
 

NoLimit95

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Don't forget to plug it back in when you put the TB back on. It's all the way at the back and the harness don't come up very high but all together, it's about a 30 to 45 min job. Your first time, maybe an hour or so.
 

NoLimit95

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the op is not gman who was asking that ?. Or did i read gmans post wrong and he was asking for the op. Post can sometimes be taken different ways by different peeps. Btw mike how did the vote go??

op

iac has been replaced on my 93 & now its worst! the car wants to shut off & then accelerates to 2,000 rpm's. It comes back down to 1,000 rpm's then starts shuttering again. It won't shift from 2nd gear & the transmission mechanic showed me the obd1 reader stating that the tps sensor is bad! Is the tps(throttle positioning sensor) the same as the iac?

My frustration from my 93 grows deeper! I'm spending cash on the car to get it ready for palm harbor & i 'm also trying to save up enough so i can paint the 97 that i need to sell in order to pay for the ce i just got but each time it seems more difficult! I'm so pissed!!!! :mad: :mad: :mad:
 

Right on the Mark

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I never saw 500 to 1000 in the OP post thats what got me and still don't see 500 to 1000 rpm. Just a mistake on my part thats all. Dispers people nothing to see here. LOL
 

UltimateSVT

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alex take the throttle body off, four 8 mm bolts, the tps in on the throttle body facing the iac if i recall, its held in with 2 phillips screws and you will not be able to take them off with the throttle body on the car, they have loctite on them from the factory and its very easy to strip the heads out, so use a bigger phillips and push real hard when breaking loose, you might want to lock the t.b in a vise so you can really push on them screws, new tps i think is around 18-20 bucks roughly. get a new throttle body gasket at the same time, 2.99 for felpro.

OMFG!!! I just finished doing all that for the IAC!!! I'm about to shoot myself & call it a day!

That sounds like IAC. Have you changed that yet?

lol... Like I said above, I'm about to shoot myself!
 

baggedtaco

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Ive chased this problem a few times myself. Ended up that the TPS voltage was way too high both times. I was using an aftermarket Throttle Body that had an adjustable TPS mount on it, which was very nice. Pretty simple to just bring the TPS voltage within limits and bolt it down, it doesnt take but just a slight adjustment clockwise or counter-clockwise to bring the voltage into the sweet spot. The Modular Mustangs link is a dead ringer.

Brad
 

NoLimit95

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OMFG!!! I just finished doing all that for the IAC!!! I'm about to shoot myself & call it a day!



lol... Like I said above, I'm about to shoot myself!

Alex, don't feel bad. This is why I mentioned making sure you plugged it up before you mount the TB back in place. I done a IAC and TPS at the same time one night. Had the car backed right outside of the garage door and had the hood off. This was on that 94. We had a storm that was about to hit any minute. I cranked the car up real quick and noticed that the idle was high and stuck high. My dad asked me if I plugged the TPS in. Then I thought back and didn't remember plugging it in. I had to unbolt the TB, get it back up enough to plug the TPS back in and then mount the TB back down. Then I had to put a few more odd and end things back on and then the hood (that I had his help with) and I done all of that in about 8 min and pulled on into the garage 3 min before the rain started coming down.

TPS is not as hard as the IAC at all. It can be done quick and since you have already had the TB off, now you know what to take loose so you can to the swap in less than 30 min, taking your time.
 

Warden

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I've been meaning to do the IAC in mine too, searched LVC and everyone seems to say that since it's such a bich getting to it that you should do both the TPS and IAC at the same time. So I have both parts sitting on my shelf, just waiting.
 

UltimateSVT

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Well, what sucks is that my IAC was fine to begin with... It was the TPS all this time! The RETARDED mechaniac that did the IAC job didn't install the black gasket that goes between the plastic intake & the throttle body! That's why it was shuttering & the rpm's were fluctuating but now that I have placed the gasket back on & started the car, the rpm's shoot right back up to 2,100 rpm's like it used to! :mad:

It sucks that he ad everything off the car & I didn't know where the TPS was. I noticed where it is on this car last night & it just sucks that I have to take apart that throttle body again!!! :confused:
 

UltimateSVT

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Ive chased this problem a few times myself. Ended up that the TPS voltage was way too high both times. I was using an aftermarket Throttle Body that had an adjustable TPS mount on it, which was very nice. Pretty simple to just bring the TPS voltage within limits and bolt it down, it doesnt take but just a slight adjustment clockwise or counter-clockwise to bring the voltage into the sweet spot. The Modular Mustangs link is a dead ringer.

Brad

Easier said than done... on my 93 it's behind the throttle body. It's going to be a pain in the @ss to uninstall, adjust, install, & if its still reving high, have to uninstall, adjust & install again... until I get it right! Worst off is that I get home at 6:30pm every day. Almost no day light. :(

My luck with this car is just horrible!!!!!!
 

baggedtaco

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You only need the key (KOEO) on to adjust the voltage. So as long as the tps is attached and plugged in you can adjust. So the TB can just be hanging however it is easiest to work on so long as you can plug the TPS in. Make sense?? If you bore/elongate those mounting holes you will have enough throw to adjust your voltage. As mentioned already it should be no more than .97

Brad
 

UltimateSVT

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You only need the key (KOEO) on to adjust the voltage. So as long as the tps is attached and plugged in you can adjust. So the TB can just be hanging however it is easiest to work on so long as you can plug the TPS in. Make sense?? If you bore/elongate those mounting holes you will have enough throw to adjust your voltage. As mentioned already it should be no more than .97

Brad

Ok, maybe it's because I saw it last night in the dark but it really seems inaccessible unless I take everything apart. Tonight I will get home & start fvcking with it.
It's very unfortunate that I cannot work on this from an angle where I can have the engine on like the old days & simply bring down the throttle acceleration. Damn electrical components!!!
 

baggedtaco

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I do see that the TB is really tucked in back there. That really does suck and you would probably have better luck just installing a new one.

Brad
 

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