jayyraad Member 19 Member For: 12y 3m 28d Posted 03/09/12 10:14 AM Share Posted 03/09/12 10:14 AM hey all this is my first post so I hope someone out there would be able to point me in the right direction to diagnose my fault in my XR-TI have an 04 mk11 and sometimes (oddly on the weekends) it will have a sudden loss in power and makes acceleration and taking off difficult, especially being manual.Iv pulled off my crossovers and checked to make sure that the throttle butterfly was operating when the accelerator pedel is depressed in different position. Found all to be okay, so I put it all together and took her for a spin under all coditions again and no matter where the throttle was it jus had NOTHING. so I kicked the throttle pedal in frustration and the proper throttle returned momentarily.I tried boosting it and it had no boost at all (felt like a laggy N/A) .. I parked the car in frustration again and I kicked the throttle pedal in neutral flat to the floor and strait back off and it reved to 2300ish RPM when the revs settled I did it again and it only went to 1100RPm...sometimes after driving for an extended period of time it will all return to normal and everything is okay. through the week.. drives well (aside from crap economy 300km to a full tank) and she idles fine. no shuuders, knocks, noises, misfires nothin.so I think that sums it all up..im leaning towards my TPS on its way out? yet to test itor my actuator is sticking? once again yet to test it.checked for boost leaks, manifold leaks, (all vacuum leaks)cleaned the boost solonoid, throttle body is SPOTLESS, umm.. im still yet to get it tuned or speak to a tuner (ill go see spirrow) but just want to do my own diagnosis work before I go start spending hard earned cash on things that wont help me.iv also plugged a scanner on it to see what fault codes come up and after this issue it has an overboosting code in it.appreciate any help. thanks all!jared. Link to comment Share on other sites More sharing options...
Falky100 Donating Members 305 Member For: 13y 1m 20d Gender: Male Posted 03/09/12 03:19 PM Share Posted 03/09/12 03:19 PM Weird...Couldnt be valve springs could it? Buggered o2 sensors? coil packs? spark plugs? the actual throttle body itself? Who knows, start at the easy stuff and work your way deeper.Good luck!John. Link to comment Share on other sites More sharing options...
MetalPhreak Member 28 Member For: 18y 5m 13d Posted 03/09/12 05:07 PM Share Posted 03/09/12 05:07 PM The pedal itself has 3 position "sensors" inside (basically variable resistor/potentiometers). If the readings from the three vary by more than a few percent the ECU detects it as an error. It's basically a safety feature in case you pedal stuffs up. Not sure if it would generate a fault code to be read via the OBD2 port. If you can get a copy of the BA manual, search it for "PPS" - Pedal Position Sensor. Its the part that the pedal connects to that sends the throttle demand signal to the PCM. I'd say its either that, or the TPS. Link to comment Share on other sites More sharing options...
bionicxr6t05 Bronze Donating Members 2,216 Member For: 13y 5m 3d Gender: Male Posted 03/09/12 08:49 PM Share Posted 03/09/12 08:49 PM Could also be a failing cat converter 1 Link to comment Share on other sites More sharing options...
Paulie2256 Donating Members 7,441 Member For: 16y 1m 8d Gender: Male Location: SE Melbourne Posted 03/09/12 08:59 PM Share Posted 03/09/12 08:59 PM Hey bionic I have a question related to this, hope OP doesn't mind.Do you know what would be causing a loud ticking noise when the pedal is flat to the floor and car in reds (engine not running)Another symptom is the engine holds revs for half a second on clutch in. Link to comment Share on other sites More sharing options...
bionicxr6t05 Bronze Donating Members 2,216 Member For: 13y 5m 3d Gender: Male Posted 03/09/12 09:21 PM Share Posted 03/09/12 09:21 PM Could be the motor in the throttlebody being a bit noisey (id have to hear it) and the second one is probably normal... U mean on a gearchange while driving the revs dont drop straight away? Link to comment Share on other sites More sharing options...
jayyraad Member 19 Member For: 12y 3m 28d Posted 03/09/12 09:59 PM Author Share Posted 03/09/12 09:59 PM So I could 'almost' rule out the actuator?My first guess was the TPS intially. But the pedel sensor. Hmm. Good point. As u said metalphreak if the values are out even for a second it could cause it to play up.. But why log no codes?Does the workshop manual have the specs and parameters of both TPS and PPS? and would I only have to test it when the fault is occuring at the time? Otherwise it would read normal, right? Appreciating any feedback thank you all! Link to comment Share on other sites More sharing options...
Paulie2256 Donating Members 7,441 Member For: 16y 1m 8d Gender: Male Location: SE Melbourne Posted 03/09/12 10:44 PM Share Posted 03/09/12 10:44 PM Could be the motor in the throttlebody being a bit noisey (id have to hear it) and the second one is probably normal... U mean on a gearchange while driving the revs dont drop straight away?Sorry I meant the revvs rise a little, then fall. I will take the intake pipe off the TB and have a look at the butterfly valve operation. Also I will log the TPS. I reckon the valve is oscillating.Jayyraad, next time you get the problem, pull over in put the car in neutral. Then rev the engine and see if the same thing occurs. If it does it is a problem with a sensor or connection. If its ok, id say the problem is mechanical. Link to comment Share on other sites More sharing options...
MetalPhreak Member 28 Member For: 18y 5m 13d Posted 04/09/12 09:10 AM Share Posted 04/09/12 09:10 AM (edited) I doubt its a blocked cat. I had that happen on my NA BF XR6. Would happily rev out to the limiter in park, but once you're driving down the road (putting some load on the motor) it hit a massive wall at 4500-5000rpm and just wouldn't rev further.Failure ModeThe Failure Mode Effects Management (FMEM)strategy will, in most cases, ensure normal operationof the vehicle if one of the PPS potentiometers fail.The ETC warning light will flash. If two or moresensors fail, the ETC will default to limp home partthrottle mode. The appropriate trouble code will belogged in memory for retrieval during Self-test mode.Not sure if its the PPS if the above doesn't happen. I'll PM you a link to a PDF with the sections on the throttle Same goes for the TPS. Should flash the ETC warning light if it detects a fault. Edited 04/09/12 09:16 AM by MetalPhreak Link to comment Share on other sites More sharing options...
bionicxr6t05 Bronze Donating Members 2,216 Member For: 13y 5m 3d Gender: Male Posted 04/09/12 09:47 AM Share Posted 04/09/12 09:47 AM (edited) You really need to take it to someone who has the equipment to diagnose it... Anything said on here is just a guess Edited 04/09/12 09:49 AM by bionicxr6t05 Link to comment Share on other sites More sharing options...
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