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Old 08-24-2003, 04:07 AM   #1
Yotsuya
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Default Throttle Position Sensor Symptom?

I've been trying to track down a problem with my car for about a month now, and it's irritating because it's not consistant; it comes and goes, and varies in magnitude.

It starts as either a rough idle, or else the car will not get gas when I'm just pushing down on the throttle (like when starting in first gear). Basically, the engine will sputter like it's not getting gas, and buck like crazy. The farther I press the gas, the sooner it comes back to normal, usually with a jerk if I'm in gear and moving.

I've tinkered with the idle air controller, fuel filter, plugs and wires to no avail, and I'm starting to look at other possibilities. I was wondering if this is something that could be caused by a faulty throttle position sensor, but since I'm not sure how it operates, I need to know how it works and if it's malfunction could cause my problem. I've also considered the fuel pump as a possibility, but I'm not sure if that's a constant running thing and not relaint on how much gas I am applying.

Any explination of these bits' operation or a possible other cause of my problem would be greatly appreciated.

thanks,
Greg
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Old 08-24-2003, 11:42 AM   #2
Keith Cournoyer
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Default sputtering

Hi Greg,
Question, do you have a ckeck enginge light? Reason I ask is because I had a similar problem and was throwing a code for a faulty(or malfunctioning) Knock Sensor. I replaced it and it went away(as well as the trouble code). Just a heads up to check that out. Good luck,
Keith
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Old 08-24-2003, 06:11 PM   #3
Yotsuya
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Keith,

Yes, I've got a CEL; not sure which one it is. It came on about a week ago, went away for a few days and came back. The problem with the engine stayed the same regardless of the CEL. I need to get the CEL checked, though. There are people around with the software; I don't have a laptop or decent PDA or I'd buy it myself.
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Old 08-24-2003, 06:38 PM   #4
sti27
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PLEASE DO NOT TOUCH OR PLAY WITH THE TPS(Throttle Position Sensor)

I say this out of concern. Back around 98-99 there was a DIY mod that said you can re-adjust the TPS for better drivability. I did this mod and could kick myself in the A**. It messes with the amount pressure you apply to the gas pedel to accelerate. (HARD to explain cause I'm no expert) But you know when you accelerate, then you let of the gas a little just to stay at crusing speed? Well when I do that, sometime I start to decelerate when trying to stay at crusing speed. In closing, get you cel checked out and try not to touch the TPS.

STI27
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Old 08-24-2003, 08:10 PM   #5
Yotsuya
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Default

I'm not planning on messing with anyting; if it's the problem, I'm ordering a replacement. I just want to track down the problem and fix it without getting raped by a dealer's service department, if possible. I need to track down the CEL.
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Old 08-24-2003, 08:38 PM   #6
sti27
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Try stoping by a AutoZone or parts store. Most will do a CEL check for free.
Also check around for a small mech. shop that works on subies. I have a great little shop about 5 mins away from my house that takes very good care me. After the dealer PISTED me off on several ocasions, I took all my buisness to the new little shop I found. Been going there eversince(about 2-3 years).

STI27
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Old 08-24-2003, 09:04 PM   #7
Yotsuya
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There are plenty of mechanically savvy owners around, but no shops other than the "tuner" types. I just need to catch an owner and have the code checked.
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Old 08-25-2003, 01:42 AM   #8
ciper
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There is a VERY small window for adjustment on the tps, the idle switch has to come on at just the right time.

Sounds more to me like a fueling issue, bad fuel pressure regulator or fuel pump/filter problem.
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