UK-POLOS.NET - THE VW Polo Forum

Hello,

My girlfriend has had a problem twice now, when pulling away here polo looses power when changing into second gear and the engine check light comes on. The first time it happen I put it down to a random error as once the car was switched off and restarted the problem had gone, now it's happened again I guess I'd better fix it!

So as it's sunday and I can't get it put on a code reader does anyone know of any common faults that would cause this? Also I'm thinking of buying a code reader for it as it would be useful anyway ... best one to get?

Thanks in advance for any help.

Damian

Hi mate, my polo does this due to the vains in the turbo being sticky. Then it goes into lump mode. There are a various number of things that can cause this. Is it a turbo diesel or what? Other things like dodger maf, vacuum leak or faulty egr causes it. Normally when it's over boosting. This is what happens to me anyway!

Hello mate thanks for the reply, I should of said it's a petrol. I was wondering about the EGR or MAF so sound like that's a good place to start.

I read somewhere that taking the maf out and driving it can diagnose if that's the problem.. And if it runs better then that's it. Had a problem last week where I was getting no boost, was just a faulty fuse. Give it a good check for any vacuum leaks etc also. Take off the egr and give it a good clean too. How many miles has it got?

Is this a 75PS engine, ie BBY?
I'd reckon that the EGR valve will not be dirty, but could be faulty in other ways - though not necessarly, these petrol engines do not tend to mess up their EGR valves although the induction end of the pipe or its port, can get clogged but that only flags up insufficient flow and does not force "limp home" operation.
You really need to get the stored fault codes read, Gendan do one for VAG cars and as I've got one (as well as VCDS) for "on the road" diagnosis, I can say that it will reveal all possible engine codes as well as SRS, AUTO TRANS and ABS fault codes, it used to cost £30>£35 delivered.

Right guys,

Thanks for all the help, for speed I borrowed a code reader off a mate but will buy one of the ones suggested for future use! Unfortuntly there are no stored codes so I'm no further in finding the problem. A friend has suggested that it could be the MAF as these do not tend to store fault codes ... anyone know if this is true or faulse??

For the record, these petrol engined cars do not have a MAF, instead there is a pressure sensor mounted on the inlet manifold - so its a MAP sensor. They do get covered in oily curd, but I'd think that if its working and not forcing fault codes to be logged then basically it will still be working well enough not to be causing this problem. One thing though to talk back against that thinking is, if the fault code reader you used was just an EOBD one, then maybe some VAG specific codes will not have been picked up.

Thanks for the info mate, I have a little update. This morning the light came on again to I drove over to her and read the code before it cleared itself again it came up with this Po121 $10pd,Po121$10 which I belive is the throttle position sensor. It looks like this part is built into the throttle body so it's new throttle body time ... at least it's a fairly simple fix!

The fault will not clear itself, though if it has been intermittant, the MIL will go off after a few engine starts have passed since the fault was there. So, that means it will remain in memory until cleared - this might cause confusion in the future, so its always better to record the fault code and clear it, I'm guessing what you tried to write was P0121 - 10 which is an intermittant fault code.

As that was an intermittant fault code, the car should be driving okay most of the time - is that true?

Throttle bodies are quite expensive - I hope that you have found that out before committing any money, the new throttle body will need to be re-aligned to the ECU - that can be done very easily if you have access to VCDS.

Thank you for your repy, It sounds likie you know an aweful lot more about this than me. Truth be told I'm more at home working on 4X4s, although I used to own a Polo myself (which never went wrong).

You are right in saying it's an intermittant fault, the car is fine most of the time and it has never done anything strange while I've been driving it.

I've spoken to GSF about the throttle body and they seems to think with the codes given it could be the throttle pedal? will the car run at all if I change either of these parts or is it a case of getting the work done somewhere with VCDS?

Thanks for all your help.

check your coil pack mate. could be running on 3 cylinders

Sorry but I posted twice last night and each time, this forum chose to change me to "not logged in" when I submitted the posting - now that is annoying to say the least, so I thought "oh bother" or something like that!!

Anyway, I'll try again today.

I don't know how well the car would run without an adaption being carried out as these cars don't use KAM like Ford etc used to do, so the voltage end stops held in memory would be those of the previous TB - though, as a standard part designed to tight tolerances I'd guess it would run, remember that is only a guess.

It would be quite handy if it was only the pedal sensor that was faulty, though I'd expect a VAG specific code reader to pick up a "better" code to lead you to that conclusion. I'd think following the lines of needing to perform adaption on the TB and EGR valve, maybe to optimise, or fully integrate the new throttle pedal sensor into the "engine control system", an adaption of that might be needed eventually - not sure on that though.

Coil pack failure - remember these cars have 4-off coils on plugs (COP) any misfiring other than "once in a blue moon" should be getting logged and reported, though it might take a few to bring on the MIL, though a VAG specific code reader would find the logged code in the ECU's memory and tell you which coil was having a problem.

Now to try to submit this!! ( oh joy, it worked!)

I'm pretty sure I had the same problem but I didn't feel a huge loss in power (1.4 Petrol Sport 100BHP). Starting from cold and revving it slightly higher (i.e I was going 60mph on a road out side of my house) the engine warning light would come on. I had other small problems connected to it too. Found out it was the lambda sensor was fecked and therefor the ECU wasn't giving the engine the right fuel/air mixture. Got it changed and works pretty well now.