Bucking and stalling... wtf?
08-05-2010, 10:58 AM
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Vehicle: 1999 Hyundai Tiburon
Bucking and stalling... wtf?
First of all I drive a 1999 Tiburon 5spd with 236000KMs. I have a cold air intake and EL Headers.
For the past 6 months or so the car has been idling really low, but never quite stalling. I keep my foot on the gas a little bit during stops to keep the idle speed from shaking the car. The problem only happens when the car is warmed up. I have been trying to figure out the problem for quite some time, replacing the upstream O2 sensor, and checking every vaccuum line for leaks. I've cleaned out the IAC and checked it for electrical problems. I've used an OBD2 tool to read the intake air temperature, air flow, and throttle position and all of them seem to be ok. Nothing has worked and up until yesterday I just dealt with it.
Yesterday after a 2 hour road trip my car started really acting weird. It stalled violently, and then started bucking at certain points through the rev range. It was a really hot day, but even today it hesitates and bucks at certain revs/throttle position. I took the TPS off and applied power to it while looking at the signal with an oscilloscope. It seemed pretty linear except I could wiggle the little plastic piece up and down which would change the signal about half a volt. I put it back in the car and started it. When I tapped it and wiggled it and the wires nothing really changed. I tried wiggling the MAF wires and still nothing!
I was gonna get a TPS from the junk yard but they only had Dae Sung (not sure on the spelling), so I wanted to just see if anyone else has had similar problems and may be able to offer me some advice.
Thanks!
For the past 6 months or so the car has been idling really low, but never quite stalling. I keep my foot on the gas a little bit during stops to keep the idle speed from shaking the car. The problem only happens when the car is warmed up. I have been trying to figure out the problem for quite some time, replacing the upstream O2 sensor, and checking every vaccuum line for leaks. I've cleaned out the IAC and checked it for electrical problems. I've used an OBD2 tool to read the intake air temperature, air flow, and throttle position and all of them seem to be ok. Nothing has worked and up until yesterday I just dealt with it.
Yesterday after a 2 hour road trip my car started really acting weird. It stalled violently, and then started bucking at certain points through the rev range. It was a really hot day, but even today it hesitates and bucks at certain revs/throttle position. I took the TPS off and applied power to it while looking at the signal with an oscilloscope. It seemed pretty linear except I could wiggle the little plastic piece up and down which would change the signal about half a volt. I put it back in the car and started it. When I tapped it and wiggled it and the wires nothing really changed. I tried wiggling the MAF wires and still nothing!
I was gonna get a TPS from the junk yard but they only had Dae Sung (not sure on the spelling), so I wanted to just see if anyone else has had similar problems and may be able to offer me some advice.
Thanks!
08-05-2010, 12:39 PM
#3
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<div class='quotetop'>QUOTE (thearkatek @ Aug 5 2010, 11:58 AM) <{POST_SNAPBACK}></div><div class='quotemain'>certain points through the rev range</div>
At which points? The more specific you can be, the more helpful we can be.
At which points? The more specific you can be, the more helpful we can be.
08-05-2010, 01:16 PM
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OK at idle it basically is always on the verge of stalling. It hesitates as soon as I hit the gas from idle, almost as if it dies a bit then jumps up. Then about half way into the the throttle it starts bucking again. Mostly between 2-4K RPM. When im coasting down a hill in say third gear just using my engine to slow me down it occasionally bucks as well.
08-05-2010, 07:31 PM
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Vehicle: 2001 Hyundai Tiburon, 2004 Kia Sorento, 2010 Kia Soul
I concur, it is the TPS.
What brand is the TPS on your car?
Other common suspects are the CKP, and the MAF being installed backwards.
What brand is the TPS on your car?
Other common suspects are the CKP, and the MAF being installed backwards.
08-05-2010, 08:33 PM
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Vehicle: 1999 Hyundai Tiburon
The TPS is a Kefico. I have changed my spark plugs months ago, it doesn't make sense that the problem would just start now with the spark plugs (at least to me). I'm gonna get a new TPS and try that, but is there anything else that could cause this? The TPS checked out when I tested it, so I'm a little doubtful that the new TPS is gonna fix it.
08-05-2010, 09:42 PM
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Off chance: have you cleaned the throttle body recently?
Spark plugs and wires are easy and free to inspect. Check them before buying a TPS.
Spark plugs and wires are easy and free to inspect. Check them before buying a TPS.
08-05-2010, 09:44 PM
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Vehicle: 2001 Hyundai Tiburon, 2004 Kia Sorento, 2010 Kia Soul
If you had the DaeSung TPS, yes, it would for SURE be the TPS.
Even with the Keifco, it can go bad too. There's even a TSB for it, and a few dozen threads about it.
What else do you have done to your car? The CKP can do the same thing, I'd look at all the sensors and see if any are loose, broken, fraying, rattling, or falling apart, before I throw any money at it.
I had my CKP come out one time, as have others, and it sucks.
Even with the Keifco, it can go bad too. There's even a TSB for it, and a few dozen threads about it.
What else do you have done to your car? The CKP can do the same thing, I'd look at all the sensors and see if any are loose, broken, fraying, rattling, or falling apart, before I throw any money at it.
I had my CKP come out one time, as have others, and it sucks.
08-06-2010, 06:01 AM
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My MAF is installed correctly, and I have cleaned the throttle body about 6 or 7 months ago, but I'm curious how this would effect it. Would it just cause the throttle to stick and not move freely? I have checked the spark plug wires and they seem to be ok.
My big question now is about the Dae Sung brand. All I can find at the junk yards are Dae Sung. There are newer ones off of an elantra that would fit. Did Dae Sung get any better with the newer parts or are they still just complete sh*t? A new TPS is gonna run me about $100 so I'd like to get a used one if possible.
Also are there any specific symptoms that would be present with a bad CKP sensor?
My big question now is about the Dae Sung brand. All I can find at the junk yards are Dae Sung. There are newer ones off of an elantra that would fit. Did Dae Sung get any better with the newer parts or are they still just complete sh*t? A new TPS is gonna run me about $100 so I'd like to get a used one if possible.
Also are there any specific symptoms that would be present with a bad CKP sensor?