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Discussion Starter #1
Ok, Got me a 97 PSD with a throttle problem, I got a video to post, Trying to upload it now, But Its like a sticky throttle, You tap the pedal and it revs up to like 1500rpm
Makes for driving it first or second gear with the manual impossible, and I have a pretty rough road to tackle in the next few days and Im dreading the thought of doing it with this throttle problem..

Ill have the video up in a few
Also Changed the TPS and IVS, So Im thinking its not in the pedal itself

Thanks guys:bowfast:
-Patch

Ok Heres the video Notice im just taping the throttle and it revs to 1500rpm.
 

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Demon Dually
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It is free revving to 1500 with no load on the engine correct?..... That looks and sounds completely normal. Is it driving any differently from past experience or is this something you just noticed? I truly don't see any problem what so ever.
 

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Discussion Starter #3
Well, Its been since day 1 at 160k miles (now 193k)
But comparing it to my 96, which is dead now, And my dads 99, its completely unstable and hardly drivable with a manual, In first or second gear

Its hard to explain.. When your driving its the same thing, I dont think I can make it run at 1200rpm, only 1500+

Stock every thing btw..
 

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Demon Dually
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Hmmm. That is strange.Instead of tapping the throttle just put you foot on the pedal so that it just touches it and see if it jumps to 1500 like that. If it does then I would say that the pedal assembly may be damaged some how but I would think more likely that the TPS is not working correctly or the PCM isn't receiving a proper signal from the TPS. I know you said that you replaced the TPS but have you checked to see if you are getting a voltage spike when applying the throttle?
 

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Check your voltage output should not be higher than 4.5 at wot. Do a search on power peddle mod as there is a way to adjust it. Might also be the reostat in the switch is pooched or dirty too...
 

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Discussion Starter #6
Hmmm. That is strange.Instead of tapping the throttle just put you foot on the pedal so that it just touches it and see if it jumps to 1500 like that
Does exactly that, like I said near impossible to hit 1200 rpm unless I do the slightest tap,

The pedal I took the sensors off was my 96, but maybe Ill but the sensors back in, And swap the whole pedal? see what happens ??

Jcart Whats this reostat your talking about ?

Also how or what switch am I testing the voltage off?
 

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Demon Dually
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The rheostat he is referring to is the TPS. It is essentially a fancy rheostat that varies the amount of voltage that the pcm sees. I would do just that and swap the entire pedal assembly out with sensors it had on it and see what happens. The switch is the TPS that you would test for voltage. Do a search for TPS testing and it will give you threads with the way to test the TPS for dead spots and other problems.
 

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Discussion Starter #8
Well with no luck testing the TPS I noticed I had some very interesting wiring going to the IVS.. What exactly is this thing normally wired to?

kinda annoyed that whomever had this truck before did a really bad job doing whatever it is they thought they were doing..
I have a spliced wire going through the firewall from the IVS connector, going some where around to the fuse box, also with an inline fuse!:doh:

Its a wiring MESS!
 

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Demon Dually
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Disconnect the inline fuse and try operating the throttle again. See if that lets it run like normal. I can't even imagine what they were trying to accomplish with that wiring. Maybe someones attempt at a high idle setup???
 

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Discussion Starter #10
disconnected the inline didn't do any thing..

This stuff kills me though, I hate electrical and wiring..
 

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Demon Dually
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I actually quite enjoy working on electrical issues but then again I am an electrician.

disconnecting the inline made no change hmmm.? Something is making the throttle jump like that and the only other component in the circuit I can think of is the PCM. Do you have access to another PCM to try out?
 

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Discussion Starter #12
I Do have my 96's PCM, which one of the cylinders went out in that waiting on a new engine.

They can interchange no problem ?
 

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Demon Dually
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Is the 96 PCM for a stick or auto? That would be the only issue.
 

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I would bet someone had some verision of a homebrew hi idle on there.
 

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Discussion Starter #16
I would bet someone had some verision of a homebrew hi idle on there.
You think so Tom? when they do those mods, They connect it straight to the IVS?
There was an unknown switch on the dash, I thought was for clearance lights, But maybe it was for the hi-idle ?

its raining, But gonna try switch out the PCM unless you got other ideas
 

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Terminator Nation
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May be that the Idle Validation Switch is not switching until the Throttle Postition Sensor position is calling for 1500 rpm. Try putting in the complete pedal assembly, maybe the IVS adjustment is good on it. Is there a lot of "dead pedal movement" before the engine changes rpm?
 

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Discussion Starter #18
well I hear the click of the switch, And what happens is it Revs with pushing it just the slightest bit all the way to 1500+

Maybe I will just swap the pedal to see, But Im unsure about the splicing and connector, not so much the switch( which I switched out from Another good pedal I had, not In my truck though)
 

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Demon Dually
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Tom and Dave have it nailed down I think. I would say that they are right in the assumption that it was a home brew high idle. I think it may have damaged the IVS in that it jumps to 1500 rpms(high idle) right off idle.
 

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Discussion Starter #20
Alright, Swapped to Known good pedal out of my 96, And it seemed to make a minor adjustment, if anything making it way more clear when it ISNT working..

I got a new video to put up with the 96 pedal in there, Clear as day to what is going on, revs and drops fine now up to like 1300RPM, But rev it 1800+ And it sticks at 1100 or so on its way back down

probably doesnt make any sense reading it, but video will be up shortly

Edit:
 
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