94 Psd, throttle off and dies?

[motox tech]

I recently purchased a 94 PSD and long story short, It had some wires chewed by a pack rat, and upon repair, I had the thing running like a top! The issue I'm having is, tonight i started it up, and for some reason it would run for a while then die! It starts right back up no problem then just idle for a few seconds! Seems like when I idle up with the foot feed everything works great, but dies if i let completely off! I can run with foot feed at 900 to 1000 rpm and its great, but dies as soon as I let off! Always starts right up! Almost seems like the Tps is outa whack! Am going to check the battery voltage tomorrow, and all the vitals, just wondering if there is anything you guys have experienced that is similar?

 

[IDIoit]

ive had a CPS act just as strange.

 

[79jasper]

See if the idle validation switch is working right.
CPS is a good start also.

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[motox tech]

Idle validation switch?

 

[motox tech]

looked at PSD bible! Thanks guys, Ill start with these things!

 

[trackspeeder]

Idle validation switch?

IVS. Tells the PCM that the throttle pedal is being pressed. Without the signal the engine will not go above idle.

 

[IDIoit]

IVS. Tells the PCM that the throttle pedal is being pressed. Without the signal the engine will not go above idle.

if it was the IVS, it should still idle, correct?

 

[79jasper]

Should, and I personally haven't heard anyone say it caused dying, but stranger things have happened.
Another good thing to check is the ICP sensor.

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[IDIoit]

I've never had an early PSD. Are they OBDI ?
Wouldn't a scanner tell you exactly what's wrong?

 

[79jasper]

The plug is technically obd2, but the system isn't.
They can be flashed over to obd2 though.
And yes, something like AE could show exactly what's going on.

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[IDIoit]

there you go motox.
as this is an online forum, we can only speculate whats wrong with your truck according to your text.
get your rig scanned, dont play the guessing game. you will only waste cash.

 

[motox tech]

Will do! Figgured out she runs fine, after you let it set for a short period of time! Seems like it only happens when you start it up and then shut it off and then start it right back up! The voltage gauge (which i understand is just a reference at best) shows there is no charge! Then when you let it set for a while, everything works without a hitch! Will get this tranny out today and diagnose, then get it on a scanner! Thanks fellas!

 

[trackspeeder]

if it was the IVS, it should still idle, correct?

Yes it will idle. When you hit the go pedal it wont come off idle.

 

[79jasper]

My thinking was, theoretically if the switch opened but didn't close when letting off, would the TPS voltage drop be able to cause it to die? Like I said, never heard of it. Guess I'm thinking outside of the box too much. Lol

Factory voltage gauge is technically function able, even though it doesn't have numbers, it will move to correspond with varying voltages.
Alternator could be weak also. These engines need proper voltage to run right.

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[IDIoit]

My thinking was, theoretically if the switch opened but didn't close when letting off, would the TPS voltage drop be able to cause it to die? Like I said, never heard of it. Guess I'm thinking outside of the box too much. Lol

Factory voltage gauge is technically function able, even though it doesn't have numbers, it will move to correspond with varying voltages.
Alternator could be weak also. These engines need proper voltage to run right.

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when it comes to electronics, i NEVER tell anyone that their wrong.
ive seen these electronics to some crazy **** first hand.
nothing is to be thrown out unless you have an exact code, even then, its a 80/20 gamble.