Throttle Response Issue *Resolved*

[MLue1]

I should have specified the intake meaning the air intake not intake manifold. I get an initial rev to 1500 rpm sometimes when if first apply the gas. Basically the second you hit the gas pedal it revs up. Before it was really bad because that in conjunction with the throttle made the car brutal to drive. The old pedal was at full throttle at like a half inch from the top. It was an on-off switch. The new pedal is not like that. I can gradually give it gas until a little beyond halfway to be at full throttle. My car has always revved up with the exception of when I had the UPS intake which was really long so I assume it is from the intake. That is why I lengthened the intake tube and it did help.

Yes I remember now,... a while ago I did try using a 3 inch corrugated intake pipe to lengthen and relocate the air intake all the way to beside the Battery (albeit without a filter); I never mentioned it coz we saw no remarkable difference in throttle response from idle, only that the setup was a bit more muted in terms of sound.

One thing of note that may help to narrow down,....since we installed the SRI, whenever we get CEL and either MAP Sensor Trouble Codes P0108 or P0106, the Throttle response goes back to like it was with Stage1,... of course my Son likes it better. You can prolly simulate getting a P0108 or another MAP code by unplugging the MAP Sensor then try starting, then plug the MAP Sensor back in and go for a drive.

 

[Wascally Wabbit1]

So I am wrong yet again. Replacing my pedal did help a lot by moving the pedal actuation further down which I contribute to some slop in the old pedal when I removed it. But the rev issue still remains. I did some testing with Vag-Com today to look at the throttle position when pressing the gas pedal. When I initially press the pedal the position sensor reading immediately jumped to 25% from 15% (this was the baseline with no pedal actuation). So the pedal is still F-d up as my range is from 15% to 80%, when it should read 0% to 100% (I have confirmed this) and it should not jump initially like that. I then turned off the car and did the previously mentioned calibration with the pedal and redid the test in Vag-Com. The pedal reading was very linear moving from 15% up through the range very smoothly with no jumps in percentage. So what this tells me conclusively is A) the pedal trick absolutely works and I can quantify it to prove it. B) My rev situation is in fact with the pedal sensor, but it must be either a short in the wiring or an ECU issue as I just replaced the sensor. I am assuming my shortened intake prior was exaggerating the issue prior so lengthening it made it less prominent but it was just a workaround not a solution.

 

[MLue1]

So I am wrong yet again. Replacing my pedal did help a lot by moving the pedal actuation further down which I contribute to some slop in the old pedal when I removed it. But the rev issue still remains. I did some testing with Vag-Com today to look at the throttle position when pressing the gas pedal. When I initially press the pedal the position sensor reading immediately jumped to 25% from 15% (this was the baseline with no pedal actuation). So the pedal is still F-d up as my range is from 15% to 80%, when it should read 0% to 100% (I have confirmed this) and it should not jump initially like that. I then turned off the car and did the previously mentioned calibration with the pedal and redid the test in Vag-Com. The pedal reading was very linear moving from 15% up through the range very smoothly with no jumps in percentage. So what this tells me conclusively is A) the pedal trick absolutely works and I can quantify it to prove it. B) My rev situation is in fact with the pedal sensor, but it must be either a short in the wiring or an ECU issue as I just replaced the sensor. I am assuming my shortened intake prior was exaggerating the issue prior so lengthening it made it less prominent but it was just a workaround not a solution.

Good find! Points to a setting or some thing out of wack that the pedal trick tries to calibrate but fails. hmmm

 

[Wascally Wabbit1]

Good find! Points to a setting or some thing out of wack that the pedal trick tries to calibrate but fails. hmmm

It is frustrating because as far as I know there is no way to calibrate the pedal or anything.

 

[MLue1]

It is frustrating because as far as I know there is no way to calibrate the pedal or anything.

Chris I hear ya, maybe it's time to AskDAP or Humble Mechanic.

Owner Paul Barrett has alot of resources that he draws from including the Humble Mechanic. The guy with the 2.5 that's having intermitent stalling, He Posted his problem here and on Vortex but never responds to the Posts, just recently had his Question answered on AskDAP HERE. Paul suggested it could be a fuel pump issue, personally I would have replaced the cheaper fuel pump relay before doing that but what do I know... .

They do a show regularly with questions asked around VW and Audi parts, performance or general automotive issues that they get.

Go ahead and AskDAP, it can't hurt.

To submit a question shoot them an EMAIL info@shopdap.com, make sure you enter #ASKDAP in the subject line.

Likewise to ask Charles the Humble Mechanic shoot him an EMAIL charles@humblemechanic.com, make sure you enter #ASKCHARLES in the subject line.

 

[Wascally Wabbit1]

Chris I hear ya, maybe it's time to AskDAP or Humble Mechanic.

Owner Paul Barrett has alot of resources that he draws from including the Humble Mechanic. The guy with the 2.5 that's having intermitent stalling, He Posted his problem here and on Vortex but never responds to the Posts, just recently had his Question answered on AskDAP HERE. Paul suggested it could be a fuel pump issue, personally I would have replaced the cheaper fuel pump relay before doing that but what do I know... .

They do a show regularly with questions asked around VW and Audi parts, performance or general automotive issues that they get.

Go ahead and AskDAP, it can't hurt.

To submit a question shoot them an EMAIL info@shopdap.com, make sure you enter #ASKDAP in the subject line.

Likewise to ask Charles the Humble Mechanic shoot him an EMAIL charles@humblemechanic.com, make sure you enter #ASKCHARLES in the subject line.

Ya I remember you talking about the humble mechanic and have watched his videos on youtube. I tried a few things today with no luck but did come across a little blurb on RossTech about the O2 sensor causing issues with the Peddle Positioning Sensor G79. It says to replace the O2 Sensor before replacing the pedal or Throttle Body. I have been getting O2 sensor errors (too rich] now and again and have been planning on replacing it. I guess now would be the time. Any suggestion on where to source one and which one to replace. I think there are 2 but heard the CA model has 3. Before the CAT and After the CAT. Not sure where the 3rd would be unless that is the one at the turbo on the GTI.

 

[MLue1]

Ya I remember you talking about the humble mechanic and have watched his videos on youtube. I tried a few things today with no luck but did come across a little blurb on RossTech about the O2 sensor causing issues with the Peddle Positioning Sensor G79. It says to replace the O2 Sensor before replacing the peddle or Throttle Body. I have been getting O2 sensor errors (too rich] now and again and have been planning on replacing it. I guess now would be the time. Any suggestion on where to source one and which one to replace. I think there are 2 but heard the CA model has 3. Before the CAT and After the CAT. Not sure where the 3rd would be unless that is the one at the turbo on the GTI.

The pre-CAT O2 Sensor is the only one used for engine fuel trim control, so thats the one you replace; the other post-CAT O2 Sensor(s) are for monitoring CAT efficiency for emissions.

EDIT: Went to the garage to see if i kept my old O2 Sensor we switched out, thinking it was causing soft performance but the new one performed the same. I couldn't find it but woulda sent it to you for testing, as it was working fine before replacement with 136k miles on it.

 

[brobst]

I tried this process out. Seems to be working. Placebo or not, car feels nicer.


Sent from my SM-G960U using Tapatalk

 

[Wascally Wabbit1]

Well, the throttle fix no longer works for me and my throttle is getting worse. I am now finally getting an error code but only if I look for the code under the engine module in Vag-Com. It does't show up when I do a scan oddly. I am getting P2122 and P2127. Basically, it looks like there is an electrical issue somewhere between the pedal and ECU or it's the ECU itself. If I feel motivated I may start digging around tomorrow looking for a frayed wire or loose connection somewhere and take some readings from the plug to see if I can narrow down if it is a signal issue or a ground issue.

At least now I know I'm not crazy.

 

[Wascally Wabbit1]

Changed out the 02 sensor yesterday. Car drives and idles soo much smoother. Gas mileage went up a lot and hesitation on hard acceleration is gone. Guess I did need a new one. The rev issue oddly has been happening less frequently as of the last week. It is either there or not when I start the car....meaning I will start the car and the pedal will be a nightmare or I will start it and it is wonderful and will remain so until I turn it off and start again and then it is another roll of the dice...nightmare or wonderful. Which will it be? I fear it is CPU related and getting a new CPU sounds like a pain. I am going to pull the CPU next weekend and have a look at it and the wires around it.

 

[MLue1]

Changed out the 02 sensor yesterday. Car drives and idles soo much smoother. Gas mileage went up a lot and hesitation on hard acceleration is gone. Guess I did need a new one. The rev issue oddly has been happening less frequently as of the last week. It is either there or not when I start the car....meaning I will start the car and the pedal will be a nightmare or I will start it and it is wonderful and will remain so until I turn it off and start again and then it is another roll of the dice...nightmare or wonderful. Which will it be? I fear it is CPU related and getting a new CPU sounds like a pain. I am going to pull the CPU next weekend and have a look at it and the wires around it.

WW, sorry im not not much help, since it is so intermitent, I don't think iots the ECU, more like an input or senor related. Just throwing this out there, by any chance did you swap some TDI parts onto the 2.5? Long shot but lets rule that out.

If you flash back to IE Stage1, how does it drive?

 

[Wascally Wabbit1]

WW, sorry im not not much help, since it is so intermitent, I don't think iots the ECU, more like an input or senor related. Just throwing this out there, by any chance did you swap some TDI parts onto the 2.5? Long shot but lets rule that out.

If you flash back to IE Stage1, how does it drive?

Ya. Flashing back to stage 1 or stock doesn't fix it. Actually went to stage 1 originally trying to fix the issue. All sensors have been replaced that would lead to the issue. No TDI parts on the car except the fog lamps. I am going to leave it for now as I have to put the car completely back to stock in October for the smog check. I'm going to try and tackle it then starting completely stock so I can rule out any mods. I personally think it is either a wire going to the ECU or the ECU itself. I have been researching a lot and when the ECU goes it seems as though it is the throttle that is affected, IE everything else will work but the throttle. So perhaps it is the beginnings of the ECU failing. I am still going to pop it out next weekend and see if there is anything obvious there.

 

[MLue1]

Ya. Flashing back to stage 1 or stock doesn't fix it. Actually went to stage 1 originally trying to fix the issue. All sensors have been replaced that would lead to the issue. No TDI parts on the car except the fog lamps. I am going to leave it for now as I have to put the car completely back to stock in October for the smog check. I'm going to try and tackle it then starting completely stock so I can rule out any mods. I personally think it is either a wire going to the ECU or the ECU itself. I have been researching a lot and when the ECU goes it seems as though it is the throttle that is affected, IE everything else will work but the throttle. So perhaps it is the beginnings of the ECU failing. I am still going to pop it out next weekend and see if there is anything obvious there.

I learnt a lot about the wiring from installing the UM/HEP SRI. That area that the MAP sensor connects to the wiring harness is pretty sensitive, lots going on there, I would be surprised ig the problem its in that area. All the wires are twisted pair to mimize cross talk etc, one of the reasons that VW Dealer replace the harness.

One BIG thing I have learnt is not to use dialectric gease on the MAP sensor, or any of the sensors, the dielectric grease mute the millivolt signal variances. You can clean the contacts on the sensor coz they are exposed but best to replace the connector contacts.

 

[Wascally Wabbit1]

Well this weekend I am going to install the 032 motor mounts and do the tranny fluid. While I am there I am going to pull the valve cover and intake manifold and go back to stock with stage 1 tune and and my air intake and see if the throttle issues persist. If so I have sourced another ECU and may pull the trigger as a last ditch effort to resolve this once and for all. I drove my car on Sunday and it drove perfect. It was awesome. Drove it yesterday and it drove like shit. Drove it today it was fine. I'm so tired of the Dr. Jeckle and Mr. Hyde effect. I am going to give my car a stripper name like Cheyenne because it's like dating a crazy stripper.

 

[MLue1]

someone say "dating strippers", now we're talking :thumbup: