Fault code 17545 Fuel trim Bank 1 - System too rich

[TheRunningMan]

Hi, my AUM 1.8T has recently thrown the above code along with feeling quite stuttery at lower speeds. Normally under light load just as it's starting to come on boost.
I've read up on the likely causes but don't want to start throwing money at parts without having a good idea what the problem is. I've only got vcds lite so am limited in what blocks I can log as well.

I tried unplugging the maf and for a while it felt better but then the problem returned, although possibly not as bad. Since then I've had to remove and recharge the battery and since I reconnected it the ASR light is illuminated, which I understand is normal but is it relevant that it didn't come on when I initially unplugged the maf?

I've been driving the car carefully and I tend to do a lot of short journeys anyway but as far as I can tell it's only really a problem at slow, low rpm speeds. I would have expected a boost leak or failing maf to be more of an issue under heavy load? I did wonder about an injector stuck open as that seemed to make more sense.

The spark plugs were looking quite worn, but as expected colour wise. I've ordered new ones anyway in case that's the issue but thought that would generate a misfire code if it was the problem? I took the fpr off and it looked fine as far as it's possible to see. I've also checked the recirc valve holds pressure by pushing the spring in and holding my thumb over the vacuum port for a minute or so. I'm also about half way through a tank of petrol with some fuels system cleaner in.

Vacuum pipes etc I have checked as best I can and most have been replaced.

Any thoughts on the most economical way to proceed??

 

[<tuffty/>]

Check the FPR isn't blocked... too rich means the ECU is trying to pull fuel out through adaptions and has reached the 25% limit of what it can do...

This is typically down to too a fuel pressure problem and the most common cause I have seen is the FPR gets blocked from the debris of rotting hoses... this artificially increases the fuel pressure...

Pull the FPR off, check if the filter is blocked by debris and look to redo your rubber fuel hoses too if its a load of black bits

<tuffty/>

 

[TheRunningMan]

Check the FPR isn't blocked... too rich means the ECU is trying to pull fuel out through adaptions and has reached the 25% limit of what it can do...

This is typically down to too a fuel pressure problem and the most common cause I have seen is the FPR gets blocked from the debris of rotting hoses... this artificially increases the fuel pressure...

Pull the FPR off, check if the filter is blocked by debris and look to redo your rubber fuel hoses too if its a load of black bits

<tuffty/>

Ok thanks I'll take a closer look. I have had the fpr off recently and there were no obvious chunks of rubber visible but I didn't closely inspect the filter.

 

[TheRunningMan]

Ok so I've checked the fpr and gave the filter a gentle clean. It's not in the best condition but not blocked. Whilst I was at it I changed the plugs.
Started the car and have the check engine light on. I scanned for fault codes and had the original running rich one as well as a cylinder misfire code. I cleared them, ran the engine for a bit then scanned again and they both came straight back.
I measured blocks 1+2 on idle briefly (see attached pic). Initially the 'Lambda control bank 1' was at 0% and it ran rough for a few seconds but then it settled to how it is in the pic.

Any further thoughts? I need the car 7 days a week so can't afford to leave it with anyone.

 

[<tuffty/>]

If its not a physical issue causing the adaptions then it could be due to a faulty MAF sensor... if it is under reading then more air is in the system than the ECU is 'seeing' so is adding more fuel off the back of the lambda sensor readings...

Difficult one to diagnose fully this way tbh but MAF sensors fail with regularity and if you haven't changed it at all or know of the last time it was changed then its not a bad shout to consider replacing it....

Just make sure its a genuine Bosch sensor from somewhere like GSF (sign up to the email and get a discount code of typically 60%)

<tuffty/>

 

[TheRunningMan]

If its not a physical issue causing the adaptions then it could be due to a faulty MAF sensor... if it is under reading then more air is in the system than the ECU is 'seeing' so is adding more fuel off the back of the lambda sensor readings...

Difficult one to diagnose fully this way tbh but MAF sensors fail with regularity and if you haven't changed it at all or know of the last time it was changed then its not a bad shout to consider replacing it....

Just make sure its a genuine Bosch sensor from somewhere like GSF (sign up to the email and get a discount code of typically 60%)

<tuffty/>

I was all set to replace the maf but after running it with it unplugged and seeing an improvement I had discounted it. I'm waiting for a replacement pcv valve (or whatever you call the one in the T-piece under the manifold) as I suspect that's faulty. Not sure if that's likely to cause the issues I'm having but worth a try. Failing that I'll try and get some readings from the maf at low rpm where the car is struggling and see what that shows.