Idle issues. Low on Funds. Can only replace one now. Which one?

[spitfire5454]

so i thought i finally had tracke ddown the cause of my idle issues but today another clue popped up via a CEL

History: im supercharged. 2x in the last 3 months, it has jsut sputtered and died while giving it gas. one time it threw a CEL but it went away in like 5mins and didnt show up on the scanner (weird, I know). Since it has gotten colder, sometimes when i start it up it either revs pretty high, revs normal or bounces between high or low. After it warms up, everything is ok. If i let it sit for 2 days, then drive it, it revs high and will accelerate with out me on the gas. Today, it started to buck whenever it would shift r slow down to about 5mph. I threw a CEL, and i was right next to an autozone so i got read : p0122 TPS sensor. After i started it back up, it went away. Drove home perfectly normal.

What ive done: Changed Fuel Filter, checked for leaks around Intake gasket

What it could be: FPR, intake gaskets, or TPS

Im really low on funds so i can only afford to fix one right now. Which one would you go for? I was pretty sold on the FPR before this, but the CEL i dunno. it jsut seems weird it would come and go away so fast. Any thoughts

[etlsport]

when my fpr went out, it seemed like the problem was made worse when the vx had only been sitting for about 30 minutes or so.. it would run perfectly after sitting overnight or longer

[Ascinder]

This sounds a lot like a problem my little brother had with his car. In cold weather especially it would rev the engine by itself then die. It turned out his was just old and due to accumulated wear and grime, the idle "choke" system was sticking, and the cold just made it worse(shrinkage making it bind). I would open your hood, have someone start the VX, then see what cables and linkages the computer is making move when it starts up and clean and re- lube them. That's what worked for him.

[Tone]

Remove and thoroughly clean the idle control valve located on the throttle body across from the TPS (which has no serviceable parts). Unplug and replug the TPS cable and use some dielectric grease on the connectors to both.

I've seen a LOT of electrical gremlins vanish (especially the intermittent HID ignitions) after applying dielectric grease to ALL electrical connections. I use it as a matter of course now anytime I unplug a connector.

If you suspect leaking intake gaskets (unlikely IF they were changed when the SC was installed), with a cold engine, have some one start the engine while you spray either starter fluid or carb cleaner all around the base of the intake - if the engine speeds up or slows down when sprayed in a particular area, you have narrowed down the leak. You can try retorquing the bolts but will probably need to replace the gasket at some point.

[CowboyErik]

just had a succesfull tranny rebuild; exhaust refit after painting everything; did plugs; serviced pumpkins to; installed new evaporator cannister to rid myself of the evap code; tonight, left soccer field, started idling high, code PO122 popped out; I pulled over, checked my oil; drove normally sense; gonna clean circuits in the morning; weird; my code reader actually said it was the "peddle" position sensor so I wondered if there was wired around the accelerator peddle and that was messed with during tranny rebuild

[CowboyErik]

"Pedal Position Sensor/Switch "A" Circuit Low Input" is that my scanner said; TPS makes more sense

[bentcipher]

If you suspect leaking intake gaskets (unlikely IF they were changed when the SC was installed), with a cold engine, have some one start the engine while you spray either starter fluid or carb cleaner all around the base of the intake - if the engine speeds up or slows down when sprayed in a particular area, you have narrowed down the leak. You can try retorquing the bolts but will probably need to replace the gasket at some point.

Per Moncha, do this first! It's the easiest and fastest way to eliminate intake gasket related issues. If that checks out OK, move on with the troubleshooting process.

I had this issue happen to me last year... Yeah, parts are expensive. Let me see if I can dig up my original post...

[bentcipher]

Here ya go... hope it helps...

http://www.vehicross.info/forums/sho...135#post237135