Intermittent power loss.

[Adam4D]

If values in mvb 031 match each other at high rpm under full throttle through 3rd/4th gear it's not fuel filter.

My advice, smoke test inlet for PCV and vac pipe leaks.

If no joy check evap valve isn't letting unmetered air through.

Smoke test exhaust for leaks before the first oxygen sensor too.

 

[paulos44]

Well I've finally got the new fuel filter on and it's made bigger all difference.
I have decided to put the original MAF back on in the morning, clear the fault code and see how it goes, as all this started a week or so after putting the Octavia one on.
Just a quickie.... Shouldn't the 2 copper posts in the MAF picture below have a connecting wire between them ?

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[paulos44]

I am leaning more and more towards a faulty MAF sensor as I've just got the following reading at 4000rpm.
I've read that at 6000rpm the reading should be about 80% of your bhp output. I don't understand why it's not bringing the MAF up in the fault code list though.......

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[Calumcjm]

Drive with your MAF unplugged and if it drives better it's a bad MAF. That value also points to it as well

 

[paulos44]

Ok will give that a go in the morning.....cheers.


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[paulos44]

Has anyone recorded their g/s MAF figures for various RPMs in their Leon Cupra ?

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[mty12345]

I am leaning more and more towards a faulty MAF sensor as I've just got the following reading at 4000rpm.
I've read that at 6000rpm the reading should be about 80% of your bhp output. I don't understand why it's not bringing the MAF up in the fault code list though.......

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Hi mate.

You can also see in the pic that the engine load is only 18%. MAF readings are only going to be 80% of your power, both at full load (full throttle) and at higher revs. They mean nothing otherwise.

Run some proper logs in 3rd gear, @ WOT, all the way to the redline and post them up. If you log groups 002, 031 and 115 that should give a good overview of whats happening.

The fact that it's the (Multi) version of the lean code, would lean more towards a maf or fueling issue rather than a vac leak, but logs will give a better idea.

 

[Adam4D]

Quite clearly see fuel +21% trim

At 4000rpm stationary you will still have vacuum.

It's a leak, disconnect maf you'll find fuel trims won't change much.

Watch fuel trims in 001 block and 032 block at same time.

 

[mty12345]

Quite clearly see fuel +21% trim

At 4000rpm stationary you will still have vacuum.

It's a leak, disconnect maf you'll find fuel trims won't change much.

Watch fuel trims in 001 block and 032 block at same time.

Why would he be at 4000rpm when stationary? 99% of the time he's at 4000rpm he's most likely going to be on boost, or on overrun, in which case the engine would be expecting a fully lean O2 reading.

If he disconnects the MAF then it will run in open loop, disabling the fuel trims, so they aren't going to change. Not sure this would achive anything other than adding confusion to his situation.

Ross tech for 17536 http://wiki.ross-tech.com/wiki/index.php/17536/P1128/004392 It doesn't mention air leaks, just MAF, O2 or lack of fuel.

If he has that big a VAC leak then surely he would also expect to get a Lean at idle code too?

 

[paulos44]

I'll do a run tomorrow and post it up if I can work out how to do it as I've never done one before and only have the VCDS LITE version.
I assume the AUQ has a rev limiter ?

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[Adam4D]

I saw fuel corrections that high I'd be smoke testing it simple as that.

Assume I am stupid all you like after a day smoke testing and remapping an S3 and removing old revo software then boot mode flashing because the ecu went stupid mid flash I'm officially through with 1.8t's today.

Post up Screenshots of 001 and 032 blocks on hot engine at idle please.

 

[paulos44]

Ok will do

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[mty12345]

I'll do a run tomorrow and post it up if I can work out how to do it as I've never done one before and only have the VCDS LITE version.
I assume the AUQ has a rev limiter ?

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I didn't realise you only had the lite version buddy. Pretty sure you can't run logs with that.

 

[mty12345]

I saw fuel corrections that high I'd be smoke testing it simple as that.

Assume I am stupid all you like after a day smoke testing and remapping an S3 and removing old revo software then boot mode flashing because the ecu went stupid mid flash I'm officially through with 1.8t's today.

Post up Screenshots of 001 and 032 blocks on hot engine at idle please.

I agree smoke testing would be a good idea, but unless you have your own kit like you obviously do, then it's not cheap to get done, and not everyone has someone local to them that offers it.

I wasn't assuming you are stupid either..... If you spent the day mapping a S3, then you obviously know far more about the 1.8t than i do.

I was just trying to point out that IMO there wasn't anything that pointed to it definitely being a air leak. I thought it could equally be a dodgy maf, O2, or maybe a failing fuel pump.

Anyway, now i know that he's got someone with your knowledge and experience helping him, i shall sleep soundly tonight and leave him in your capable hands.

 

[paulos44]

Well here's a display of the engine warmed up on tickover....VCDS LITE doesn't allow me past block 25 so I think I need to go and get a proper diagnostic check....

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[paulos44]

Ive just been out and done a 3rd gear log to 6000rpm but only in blocks 1,2 and 3.
I cant post it up as it keeps coming up....You have uploaded the maximum of 5 files.....
The car ran as it should for 15 miles.:confused....all i did to it before the run was replace 2 blown number plate bulbs

 

[mty12345]

Yeah it's difficult without proper logs mate. If you plan on keeping the car long term then the full version of VCDS is probably a good investment.

If it is running ok now, then i'd just keep an eye, check for fault codes and see if it reoccurs.

The "warm engine on idle" screenshot doesn't give me any more clues tbh. I'm not sure what adam4d was hoping to tell from it? Maybe he will come and cast his expert eye over it soon

 

[paulos44]

Photos below of 2 runs.... doesn't make much sense as the MAF reading is lower for the higher rpm run......

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[paulos44]

Well, the car has ran absolutely fine for the last 100 miles, since I did 3 runs in 3rd to around 6000rpm.....maybe there was a fuel blockage somewhere.

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[paulos44]

Well, this morning the car was running fine and then instantly felt as if it had lost 100 bhp.
Off to Midland VW next week for a smoke and diagnostic check.

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