Hey guys, new to the forum but long time reader. I hope someone can point me in the right direction on this one and I hope I have posted in the right section! About 2 months ago, I was driving the Meg normally and upon pressing the clutch in to shift gears, the revs immediately took off on its own to the rev limiter and kept bouncing off the limiter. Shut the car off straight away. I then turned the car back on and the revs immediately picked up again and went all the way to the rev limiter and kept bouncing off the limiter. ABS light and engine light came on. Got it towed to local specialist who ran CLIP and showed a number of error faults including UHC, ABS speed sensors and a few others which I cannot recall at the moment. Strangely enough the car was behaving normally and idling perfectly. Later that day the engine and ABS light went off and we ran the diagnostics again. This time there were no error codes and we could not replicate the problem. I took the car home and it was behaving normally but I did notice a little bit of rev hang (is this normal?) which I hadn't noticed before, probably just was being super paranoid. A couple days ago the problem came back again and in a similar manner of driving, but this time only the engine light came on. I let the car sit for about 30mins and the engine light disappeared again and car behaved as normal. Took it to the local specialist again and the diagnostics showed no errors. The throttle body was cleaned, butterfly valve was checked and was fine (has good spring/tension), there were no vacuum leaks, connectors were cleaned around the ECU and the air intake pipes were checked with no noticeable problems. Took the car back home again and rev hang has become a little more noticeable and I feel it revs ever so slightly on its own when the clutch is pressed to change gears. I am currently at odds as to what it may be and hope that someone could point me in the right direction. Car has been serviced meticulously and have not had any issues with it. I only drive it once a week (twice if I'm lucky).
I have had the engine revving a couple of times last year, found that if you stamp on the throttle peddle and let off as quick as you can a couple of times, that sorted it for me, worth trying. A new throttle peddle would have sorted it but they are well over £100 a go
As for the abs and engine light, i'm not sure may be a coincidence, see if the stamping on the throttle works first.
Thanks for the reply Ian, I would try anything right about now! Do you mean stomp on it while the problem is occurring? Or literally just do it now and that should reset some signal somewhere along the line so it doesn't happen again? Surely there's something more to it and we shouldn't need to stomp on the throttle to fix the issue? The lights coming up on the dash is definitely a coincidence.
I should also add that the throttle does not stick at all when this happens and returns to its normal position
carbon track on gas peddle worn, seeing few these now, easy to replace just couple 10mm bolts and undo the multi pin connector and pedals out
the actual peddle doesn't stick, thats the silly part about it, if you do it when the engine is running you will know it's that, i do mine normally first thing before i start the engine, do it a dozen or so times and it seems to work. I will one day buy a throttle peddle unit
i took my throttle peddle unit out, tried to open it to clean it but its a sealed unit, so i doused it in electrical contact cleaner made it better
From the logical point of view, on a drive-by-wire actuation, there´s always the danger of - if a sensor is failing - engine racing if the sensor reads bullshit like full throttle. So normally, those sensors have to be redundant, you need two ones. If one failes, the likelihood that the other also fails is almost zero. If one reads full throttle and the other read part throttle or idling, there must be a plausibility check what tells the ECU that there´s something completly wrong and the engine has to run in fail-safe mode. If that happens what has happened on our colleagues car, I would check out both sensors respectivly the part(s) what are including these sensors. Maybe there are two Potentiometers coils independant in one housing, It should work. I don`t know, it´s just my reflections. I could even suggest that there´s an official regulation to implement 2 sensors on that critical functions. It could be the sensor at the gas pedal or the sensor at the throttle Body. Furthermore, I`ve no idea what could be wrong at the engine to make it racing. On Diesels, it can happen once they are aspirating their own engine oil from the engine ventilation if the oil level is far too high. Then engine racing is - very rarely - an known issue. On an gasoline engine not.
With a CLIP or any diagnostic similar, you can check what % is opening the throttle while your are actuating on pedal. Never seen a throttle body failing, but many pedals!
Thanks for the responses. I'm leaning toward replacing the pedal. Can anyone recommend somewhere to purchase an OEM pedal that's decently priced and delivers to Australia? We seem to get ripped off over here lol
you could try RPD on here, might take a while due to the circumstances around here. I have driven mine for the first time in months, nt had the sticking problem at all today, last time a stamped on the throttle a good couple of dozen times (with the engine off) and it hasn't happened since
I know Australia is huge, but can't you get someone with a similar car and see if the same thing happens? like #oldschoolracer said, in the diesel engine, many times they do that alone, but in gasoline, it's weird...
Hey guys just an update.... Replaced the throttle pedal and immediately noticed the car was a lot smoother. I also noticed fuel consumption had dropped from 19.1l/100km to 17.4l/100km whilst driving it home from the workshop. However, I think the problem still persists. I just washed my car and went for a short drive (not too spirited) and the economy went up as expected so decided to let idle and monitor the fuel consumption. I noticed the fuel consumption then went from 17.9l/100km to 18.1l/100km. Car was only idling for 5 mins. So essentially consumption is going up whilst idling? Is this even normal? I think this is an electrical issue where the water is tripping something. Any ideas??
You really need to do a journey that you normally do and go from there, one thing that does alter the fuel consumption a lot is the thermostat, my gauge was reading one mark lower, then i realised that it was using more fuel than normal, i changed the thermostat and it got better straight away. I know on a run i get between 30-32 mpg and with the thermostat problem it dropped to 27 ish
Very interesting Ian...I suspect my work temps are a bit lower. Never go more than 2nd mark and I think it would be in the 3rd.
It needs to point straight up or slightly over, (half a needle width ish). The ecu thinks the car isn't quite up to temperature so its running a bit rich thus using a bit more fuel.
Ok master, time to order a thermostat...Shame I remove the battery one week ago, was my chance to do it
You have a mk3 don't you ???? if so you will need to remove the bumper, so you can get the air out of the radiator
The needle in the 250's doesn't point straigh, I think only 265/275 do that! correct me if I'm wrong......
My 225 one did. not sure on a 250, mines a 265 just going by what mine shows, i would have thought they would have all been the same, though i'm not sure.
Really? Need to remove the bumper to purge the circuit?? When did change the water pump didn´t need it...
Nop, in the 265/275 the needle is more accurate! In the 250 the normal temperature is before the needle reaches the middle
Just be aware that the temperature could go up a lot if there is air in there. The in and out of the radiator are about 2/3 up the sides, so if air gets in there is no way it will self bleed
Yep, If you search here on the forum, you will "see" some cases of cars (250) with the needle never reaching the middle under normal conditions! But, as in the 265/275, the needle is more accurate, in the 250 "you" are mistaken in the temperature values. Of course there are symptoms of the thermostat not being in the best condition, but I think you will know that, because you know your car better than anyone
You´re right, no one knows your car like you, but in my case, only have 2 months with it and can´t drive it because the fucking Covid
