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Discussion Starter #1
Well, I'm pretty much at my wits end now, so I'm turning to my favorite resource on the net for information. The problem, as of right now, seems to be my TPS due to having thrown a TPS performance code several times...DTC P0121: Throttle Position Circuit Range/Performance Problem to be precise.

Since throwing this code, I have done the following:
1. ran multiple ground checks on all my wires
2. replaced the TPS with a brand new Hyundai OEM sensor
3. redid the splice connection for my TPS on my Mafterburner
4. pulled my hair out...

As for what the car is doing...that's the crazy part. I can ONLY recreate the problem on the highway, and I must drive at least 30 - 45 minutes straight (normal driving - no boost) before it will start acting up. When the problem occurs, the car will just feel like it loses all acceleration (just like hitting the rev limiter), and then after a couple of seconds pass, the car kicks back to life and runs perfectly again. This will just keep cycling over and over again...and you can see the voltage drop on the TPS (with the mafterburner software) during this whole ordeal. Now, the crazy part about this is that, in order to fix this temporarily, all that I have to do is reset the ECM by pulling the fuses for a few minutes. After I do this, the car will run great and it will take another long drive to get it to act up again.

So, as you can see, I'm running out of ideas. The ONLY other thing that I haven't ruled out is the ECM. I mean it might be possible that there is something inside the module that is freaking out when the car goes into limp mode on the highway, but I don't have another ECM to test this theory...and I'm not sure that I want to drop the cash for a used one to find out that I'm wrong. So if anyone has any good ideas or possible solutions I'd be very appreciative of any info. Thanks.
 

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Macatron said:
Well, I'm pretty much at my wits end now, so I'm turning to my favorite resource on the net for information. The problem, as of right now, seems to be my TPS due to having thrown a TPS performance code several times...DTC P0121: Throttle Position Circuit Range/Performance Problem to be precise.

Since throwing this code, I have done the following:
1. ran multiple ground checks on all my wires
2. replaced the TPS with a brand new Hyundai OEM sensor
3. redid the splice connection for my TPS on my Mafterburner
4. pulled my hair out...

As for what the car is doing...that's the crazy part. I can ONLY recreate the problem on the highway, and I must drive at least 30 - 45 minutes straight (normal driving - no boost) before it will start acting up. When the problem occurs, the car will just feel like it loses all acceleration (just like hitting the rev limiter), and then after a couple of seconds pass, the car kicks back to life and runs perfectly again. This will just keep cycling over and over again...and you can see the voltage drop on the TPS (with the mafterburner software) during this whole ordeal. Now, the crazy part about this is that, in order to fix this temporarily, all that I have to do is reset the ECM by pulling the fuses for a few minutes. After I do this, the car will run great and it will take another long drive to get it to act up again.

So, as you can see, I'm running out of ideas. The ONLY other thing that I haven't ruled out is the ECM. I mean it might be possible that there is something inside the module that is freaking out when the car goes into limp mode on the highway, but I don't have another ECM to test this theory...and I'm not sure that I want to drop the cash for a used one to find out that I'm wrong. So if anyone has any good ideas or possible solutions I'd be very appreciative of any info. Thanks.
I doubt your TPS voltage is the only thing dropping off but if you have an AFC or a Mafter i'll bet your monitoring it since that's the code you're getting...but then again i'd like to know the source of your evaluation that P0121... it may be that that is not in fact a TPS code or, it could be that there is a ghost code there in that sometimes it's another problem in the system that could cause the TPS voltage to drop off... with all those wires in that main harness there you could have a short anywhere between the TPS and the ecu if the wires arent securely shielded.

Are you using your cruise control when this is happening? It may be that the ecu disregards the throttle position sensor when the cruise is on and calculates load based on MAF reading and vehicle speed along with intake air temp.... although i'm just totally firing in the dark there i have no data to back it up...something to pay attention to though just incase.

Another thing to check is look for carbon buildup on the back of the throttle plate... you'd be surprised some of the weird issues that can cause...

Lastly, i'd say maybe you might consider replacing the fuse for the sensor/inj spot in the engine bay box. It's a 10 amper on the left of the cluster (facing the pass side from the driver's side of the engine). It may be that the fuse is faulty and while it's not popping it might be losing conductivity when it heats up.

I may be totally off because this is a very unusual issue, but if any of those are the problem and it works, more power to you.
 

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Do this after you get the code. You can just skip to the last part

SERVICE MANUAL Applies to: Tiburon 2003GROUPFuel SystemTroubleshooting (SIEMENS EMS)






DTC

Diagnostic item

P0121
P0122
P0123
Throttle Position Sensor Circuit Range/Performance Problem
Throttle Position Sensor Circuit Low Input
Throttle Position Sensor Circuit High Input

TEST PROCEDURE

 

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Did you check the voltage on your tps? If you remove it or loosen it, it pivots slightly (like a distributor cap) and while it only moves slightly, that position will change the voltage. If you look at your mafterburner program, go to the tps voltage and have someone loosen the tps screws and pivot it slightly and the tps voltage will alter. (thanks tc).
 

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bagpiper said:
Did you check the voltage on your tps? If you remove it or loosen it, it pivots slightly (like a distributor cap) and while it only moves slightly, that position will change the voltage. If you look at your mafterburner program, go to the tps voltage and have someone loosen the tps screws and pivot it slightly and the tps voltage will alter. (thanks tc).

If that was the problem though, wouldn't you think that it would be evident at all times?
 

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ichijin mikomi said:
If that was the problem though, wouldn't you think that it would be evident at all times?
You're probably right. I was just focusing on this:
This will just keep cycling over and over again...and you can see the voltage drop on the TPS (with the mafterburner software)
Off the the top of my head, it may be a ground problem?
 

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Discussion Starter #7
ichijin mikomi said:
I doubt your TPS voltage is the only thing dropping off but if you have an AFC or a Mafter i'll bet your monitoring it since that's the code you're getting...but then again i'd like to know the source of your evaluation that P0121... it may be that that is not in fact a TPS code or, it could be that there is a ghost code there in that sometimes it's another problem in the system that could cause the TPS voltage to drop off... with all those wires in that main harness there you could have a short anywhere between the TPS and the ecu if the wires arent securely shielded.
Well, as for the source of the P0121 code, I got that straight from the code book after reading the code number with my scan tool. But I have also wondered if it may be something else that is throwing this code like you suggested. That's one of the reasons I ended up redoing the splice connection for my TPS wire on my Mafterburner.

ichijin mikomi said:
Are you using your cruise control when this is happening? It may be that the ecu disregards the throttle position sensor when the cruise is on and calculates load based on MAF reading and vehicle speed along with intake air temp.... although i'm just totally firing in the dark there i have no data to back it up...something to pay attention to though just incase.
Well, as of right now, I don't even have the cruise control module pluged in because I'm still waiting for T.C. to develope a new, longer, cruise control cable. But, now that I think about it, that is one of the only things that I don't have on my car that was there before the install. The reason I say that is because I didn't start having this problem until after I installed my supercharger. Now, I'm not saying that the blower caused this because, as far as I know, I'm the only one having this problem. So, with that said, I wonder if the ECU is acting up because it sees that the cruise control is unplugged. Is that even possible?

ichijin mikomi said:
Another thing to check is look for carbon buildup on the back of the throttle plate... you'd be surprised some of the weird issues that can cause...
Definitely good to go here. I just cleaned it again the other day to make sure. :3_winkthu

ichijin mikomi said:
Lastly, i'd say maybe you might consider replacing the fuse for the sensor/inj spot in the engine bay box. It's a 10 amper on the left of the cluster (facing the pass side from the driver's side of the engine). It may be that the fuse is faulty and while it's not popping it might be losing conductivity when it heats up.
Now that's definitely something I haven't tried or thought of yet, but, hey, I'm open for anything at this moment. Who knows...it may do something.

ichijin mikomi said:
I may be totally off because this is a very unusual issue, but if any of those are the problem and it works, more power to you.
The only thing that still got me stumped, though, is the fact that I can make everything work again by simply reseting the ECU. That alone is starting to make me suspect my current ECU, but, then again, it doesn't fit the current problem of this happening right after my supercharger install. Any ideas about this? Also, speaking of ECUs, does anyone know of a reliable place to by a good used one for a reasonable price (around $200-$300)? Thanks.
 

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Discussion Starter #8
jordan23ryan said:
Do this after you get the code. You can just skip to the last part

SERVICE MANUAL Applies to: Tiburon 2003GROUPFuel SystemTroubleshooting (SIEMENS EMS)






DTC

Diagnostic item

P0121
P0122
P0123
Throttle Position Sensor Circuit Range/Performance Problem
Throttle Position Sensor Circuit Low Input
Throttle Position Sensor Circuit High Input

TEST PROCEDURE
Hey those look really familiar! :3_winkthu Yeah, I ended up printing those exact flow charts off of All Data (at work), but I didn't know the voltage specifications in order to know if it the readings were within specifications. So, by chance, do you happen to have those as well? Thanks bro.
 

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Discussion Starter #9
bagpiper said:
You're probably right. I was just focusing on this:

Off the the top of my head, it may be a ground problem?
Yeah, I kinda ruled out the TPS module alone due to the fact that the one I replaced it with is doing the exact same thing my first one was doing. As for a ground problem (which I've had quite a few people suggest), wouldn't it be happening all of the time as well? Also, if it was a ground problem, would it simply go away by reseting the ECU? I mean, don't get me wrong, I'm not trying to say it's not a grounding problem I'm just trying to figure out WHY, that's all. Thanks.
 

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I'm just throwing a possible wild card out there with maybe a ground problem because you have tried a multitude of fixes. When you do your initial start-up on your mafterburner, does it go green, red, and back to green? Have you talked with TC?
 

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Macatron said:
Well, as for the source of the P0121 code, I got that straight from the code book after reading the code number with my scan tool. But I have also wondered if it may be something else that is throwing this code like you suggested. That's one of the reasons I ended up redoing the splice connection for my TPS wire on my Mafterburner.



Well, as of right now, I don't even have the cruise control module pluged in because I'm still waiting for T.C. to develope a new, longer, cruise control cable. But, now that I think about it, that is one of the only things that I don't have on my car that was there before the install. The reason I say that is because I didn't start having this problem until after I installed my supercharger. Now, I'm not saying that the blower caused this because, as far as I know, I'm the only one having this problem. So, with that said, I wonder if the ECU is acting up because it sees that the cruise control is unplugged. Is that even possible?



Definitely good to go here. I just cleaned it again the other day to make sure. :3_winkthu



Now that's definitely something I haven't tried or thought of yet, but, hey, I'm open for anything at this moment. Who knows...it may do something.



The only thing that still got me stumped, though, is the fact that I can make everything work again by simply reseting the ECU. That alone is starting to make me suspect my current ECU, but, then again, it doesn't fit the current problem of this happening right after my supercharger install. Any ideas about this? Also, speaking of ECUs, does anyone know of a reliable place to by a good used one for a reasonable price (around $200-$300)? Thanks.

i can get u an 03 or 05 for 35 bux. pM me.
 

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Discussion Starter #12
bagpiper said:
I'm just throwing a possible wild card out there with maybe a ground problem because you have tried a multitude of fixes.
I understand where you're coming from...I appreciate the help I can get though! :3_smile:

bagpiper said:
When you do your initial start-up on your mafterburner, does it go green, red, and back to green? Have you talked with TC?
Well, ever since replacing my Mafterburner a few months ago, it's been working perfectly. When you start the car (or turn the key to on) I'll get green for power, then red will come on for the self test and then go back out like it's supposed to.

As for talking to TC...let's just say he's gotten plently of quality cell minutes logged to my number. LOL I just wish I could figure this damn thing out. I mean, I LOVE my blower, it's just that I can never seem to get EVERYTHING figured out on my car all at once. F/I is great...but it can also be a major PITA!
 

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Macatron said:
Well, I'm pretty much at my wits end now, so I'm turning to my favorite resource on the net for information. The problem, as of right now, seems to be my TPS due to having thrown a TPS performance code several times...DTC P0121: Throttle Position Circuit Range/Performance Problem to be precise.

Since throwing this code, I have done the following:
1. ran multiple ground checks on all my wires
2. replaced the TPS with a brand new Hyundai OEM sensor
3. redid the splice connection for my TPS on my Mafterburner
4. pulled my hair out...

As for what the car is doing...that's the crazy part. I can ONLY recreate the problem on the highway, and I must drive at least 30 - 45 minutes straight (normal driving - no boost) before it will start acting up. When the problem occurs, the car will just feel like it loses all acceleration (just like hitting the rev limiter), and then after a couple of seconds pass, the car kicks back to life and runs perfectly again. This will just keep cycling over and over again...and you can see the voltage drop on the TPS (with the mafterburner software) during this whole ordeal. Now, the crazy part about this is that, in order to fix this temporarily, all that I have to do is reset the ECM by pulling the fuses for a few minutes. After I do this, the car will run great and it will take another long drive to get it to act up again.

So, as you can see, I'm running out of ideas. The ONLY other thing that I haven't ruled out is the ECM. I mean it might be possible that there is something inside the module that is freaking out when the car goes into limp mode on the highway, but I don't have another ECM to test this theory...and I'm not sure that I want to drop the cash for a used one to find out that I'm wrong. So if anyone has any good ideas or possible solutions I'd be very appreciative of any info. Thanks.
Mine did the same thing with no code being thrown...I had the tcm reprogramed and it works fine now.I know your having a different problem but if your dropping voltage check it in a different spot when its acting up might be a voltage problem for the whole car.It seems that that was my problem and it fried the tcm.
 

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Discussion Starter #15
naturalkiller said:
Mine did the same thing with no code being thrown...I had the tcm reprogramed and it works fine now.I know your having a different problem but if your dropping voltage check it in a different spot when its acting up might be a voltage problem for the whole car.It seems that that was my problem and it fried the tcm.
Hmmm...so yours was doing the same thing, but reprogramming the ECU fixed it? Interesting...maybe my ECU is the problem after all. The only thing I'm wondering though...is whether or not I'd actually be able to reprogram my ECU with the Mafterburner installed? I mean, my car won't run with out it due to the fact that I'm running larger injectors (460cc), but I'm not sure if the dealer can still reprogram it with the tuner hooked up to it. Anyone know for sure about this?
 

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Macatron said:
Hmmm...so yours was doing the same thing, but reprogramming the ECU fixed it? Interesting...maybe my ECU is the problem after all. The only thing I'm wondering though...is whether or not I'd actually be able to reprogram my ECU with the Mafterburner installed? I mean, my car won't run with out it due to the fact that I'm running larger injectors (460cc), but I'm not sure if the dealer can still reprogram it with the tuner hooked up to it. Anyone know for sure about this?

They should be able to flash the ecu through the obd port.

Btw Mac did you ever get this resolved?
 

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Discussion Starter #17
Boostology said:
They should be able to flash the ecu through the obd port.

Btw Mac did you ever get this resolved?
Well, currently, it's on the back burner due to my car getting broke into (http://www.newtiburon.com/forums/showthread.php?t=87702&page=1&pp=30http://www.newtiburon.com/forums/showthread.php?t=87702&goto=newpost), but I should have the new ECU I ordered here soon. So, after I get my car fixed up again, I'll be able to see if that, in fact, "cured" the problem. I'll be sure to post up here if it does though.
 

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yay 35 dollar ecu!
 

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Discussion Starter #20
Well, I'm resurrecting this old thread with hope that someone on newtib will be able to finally figure out what, exactly, my car's issue is (refer to my first post).

Here is a newly revised list since throwing this code. I have done the following:
1. ran multiple ground checks on all my wires
2. replaced the TPS with a brand new Hyundai OEM sensor
3. redid the splice connection for my TPS on my Mafterburner
4. replaced the ECU with a known good one.
5. cleaned MAF sensor - didn't do anything for me.
6. replaced MAF sensor with Hyundai OEM sensor.
7. cursed at my Tib and threatened to sell it and/or drive it off a cliff. :3_saai:

So anyway, with that said, I really don't know what else to replace or even check for that matter. There are only TWO main components that are directly responsible for throwing a P0121 code and that is the TPS and the MAF sensor. The performance code is thrown due to one of the two not agreeing with the other.

Well, there you have it...I'm really at a loss here on this guys. I really makes me sick to my stomach that I FINALLY have my Tiburon almost exactly the way I always wanted it to be, but can't enjoy it because I stupid problem such as this. Now, I really don't want to get rid of my ride because I love it to death, but, if this problem persists, I really don't know what else to do.

HELP! :3_saai:
 
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