987 Boxster S 3.4 throttle problem
02-27-2017, 04:08 PM
#1
4th Gear
Thread Starter
987 Boxster S 3.4 throttle problem
I have a throttle issue with my 2007 Boxster S and it does not quite resemble other problems I have read about (and I have been searching a lot).
I was out driving and everything was as it should be then all of a sudden I lost acceleration. It felt like I had a 80bhp engine. (Long story: It was actually quite scary since I was merging from one freeway to another and in the merging lane a full size truck was cruising at 70 mph. Normally I just put my manual in 4th and pull ahead but this time almost nothing happened. Acceleration was about 1mph per second. I had to brake and pull out into the safety lane until it passed.)
DME fault code is P0121 Throttle positioning sensor (Durametric Pro)
Symptoms are complete lack of response giving more than 10% throttle. The car starts fine, no misfire, no sounds and no hesitations in initial throttle response. Driving slowly you don’t notice anything unusual. Throttle 0-10% is perfect. The car just stays at 10% throttle not matter if you press the pedal down half an inch or all the way down.
I did some quick sensor readout and
TPS1 was 0.74V
TPS2 was 4.23V
They both respond to % of throttle given but then the curve falls back quite quickly. I might have to do some logging and it would give more sense.
I have not found anyone having the similar problem with their 987’s and I do not even know where to begin looking for the Throttle Positioning Sensor or how to diagnose the issues further.
Maybe someone here can help or is familiar with the throttle system on the 987. It would be greatly appreciated
My Boxster S is a 2007 with the 3.4 H engine. It has 71k miles and is bone stock except for Cargraphics exhaust with 200 cells race cats. Headers, intake, airfilter all stock.
I was out driving and everything was as it should be then all of a sudden I lost acceleration. It felt like I had a 80bhp engine. (Long story: It was actually quite scary since I was merging from one freeway to another and in the merging lane a full size truck was cruising at 70 mph. Normally I just put my manual in 4th and pull ahead but this time almost nothing happened. Acceleration was about 1mph per second. I had to brake and pull out into the safety lane until it passed.)
DME fault code is P0121 Throttle positioning sensor (Durametric Pro)
Symptoms are complete lack of response giving more than 10% throttle. The car starts fine, no misfire, no sounds and no hesitations in initial throttle response. Driving slowly you don’t notice anything unusual. Throttle 0-10% is perfect. The car just stays at 10% throttle not matter if you press the pedal down half an inch or all the way down.
I did some quick sensor readout and
TPS1 was 0.74V
TPS2 was 4.23V
They both respond to % of throttle given but then the curve falls back quite quickly. I might have to do some logging and it would give more sense.
I have not found anyone having the similar problem with their 987’s and I do not even know where to begin looking for the Throttle Positioning Sensor or how to diagnose the issues further.
Maybe someone here can help or is familiar with the throttle system on the 987. It would be greatly appreciated
My Boxster S is a 2007 with the 3.4 H engine. It has 71k miles and is bone stock except for Cargraphics exhaust with 200 cells race cats. Headers, intake, airfilter all stock.
02-27-2017, 11:24 PM
#2
Rennlist Member
I had a lack of throttle response scenario exactly like you've described on a 996 with the 3.4 engine. I didn't hook up a Durametric at the time, but I did remove the throttle body and the MAF and thoroughly cleaned both using CRC brand cleaner specific to each item.
I'm not sure which one was the culprit but this completely and permanently cured the problem. IIRC both appeared to be fairly clean to begin with, but the cleaner running off onto a paper towel did look a bit dirty.
I did this cleaning based upon recommendations obtained in the 996 forum as it seemed like a somewhat common problem others encountered.
You might truly have a defective throttle body or it might just be dirty.
I'm not sure which one was the culprit but this completely and permanently cured the problem. IIRC both appeared to be fairly clean to begin with, but the cleaner running off onto a paper towel did look a bit dirty.
I did this cleaning based upon recommendations obtained in the 996 forum as it seemed like a somewhat common problem others encountered.
You might truly have a defective throttle body or it might just be dirty.
02-28-2017, 01:33 AM
#3
4th Gear
Thread Starter
Thank for the info and advice. The MAF might very well be the culprit. Will do some logging tomorrow and include the Throttle %, MAF along with the other throttle related sensor values.
Not gotten to taking of the top engine latch yet but will open it up and test drive with the MAF disconnected.
I got some advice today that it might actually be the TPS located in the gas pedal assembly that is the culprit. Used ones sell for $50 on Ebay so thinking of just ordering one.
Interesting with the throttle body. On my old 2006 Boxster 2.7 that was running otherwise perfect I long had an issue where the engine revs were hunting at idle when engine was warm. Cleaned the MAF - Did not help. Then removed the throttle body and it was quite dirty with lots of residue around the throttle valve. Cleaned it and after that the H6 was spinning like new at idle.
Will post some values tomorrow along with doing some tests of the MAF. TPS, MAF or Throttle body is where it all leads.
Not gotten to taking of the top engine latch yet but will open it up and test drive with the MAF disconnected.
I got some advice today that it might actually be the TPS located in the gas pedal assembly that is the culprit. Used ones sell for $50 on Ebay so thinking of just ordering one.
Interesting with the throttle body. On my old 2006 Boxster 2.7 that was running otherwise perfect I long had an issue where the engine revs were hunting at idle when engine was warm. Cleaned the MAF - Did not help. Then removed the throttle body and it was quite dirty with lots of residue around the throttle valve. Cleaned it and after that the H6 was spinning like new at idle.
Will post some values tomorrow along with doing some tests of the MAF. TPS, MAF or Throttle body is where it all leads.
03-03-2017, 11:55 AM
#4
4th Gear
Thread Starter
Just got the used throttle pedal and SUCCESS, instead of 0-10% throttle it is now 0-100%
Short DIY - Throttle problem Porsche 987/997 Gen 1
Symptom: Throttle is only responding to initial input from your right foot, no other missfire, hesitation or unusual sounds etc.
DTC P0121 only
Solution: Likely the throttle pedal assembly that needs replacement. Part number 99742301902 (I got it used on ebay for a total of $43 inc shipping and tax)
DIY guide
1 screw next to the throttle pedal (philips)
slide the pedal up and it comes loose
1 easy to push pin on the wire harness
revers process with spare part
Takes about 1 minute to do and add about 1 more figuring it out
Short DIY - Throttle problem Porsche 987/997 Gen 1
Symptom: Throttle is only responding to initial input from your right foot, no other missfire, hesitation or unusual sounds etc.
DTC P0121 only
Solution: Likely the throttle pedal assembly that needs replacement. Part number 99742301902 (I got it used on ebay for a total of $43 inc shipping and tax)
DIY guide
1 screw next to the throttle pedal (philips)
slide the pedal up and it comes loose
1 easy to push pin on the wire harness
revers process with spare part
Takes about 1 minute to do and add about 1 more figuring it out
03-03-2017, 12:51 PM
#5
Rennlist Member
Mikee,
I'm glad it was that easy to figure out. Another experience to add to the collective knowledge about these cars.
The accelerator pedal on these cars was roughly the same unit from about 2000 through at least the change to 991 and 981 vehicles.
The removal and reinstallation you describe fits perfectly with the throttle pedal work I did on my old '01 Carrera.
I'm glad it was that easy to figure out. Another experience to add to the collective knowledge about these cars.
The accelerator pedal on these cars was roughly the same unit from about 2000 through at least the change to 991 and 981 vehicles.
The removal and reinstallation you describe fits perfectly with the throttle pedal work I did on my old '01 Carrera.
