A4 - 2006 BRD 170 after 3000rpm hesitate, coil plug flash and limp home mode p0234

[ZK3]

Hopefully posting in right place, always scanned through forums when had a3 now got A4 2.0 diesel, engine code BRD 170bhp, recently bought driving back it felt jerky/hesitating in 3/4 gear about 2500, up to 5/6 would let me get up to 3000-3750 but eventually coil light would flash and limp home mode. Turn engine off and on and the limp home mode would disappear and could drive on fine. Currently just controlling the revs and avoiding problem but takes away the fun of the car!

Still has enough power but obviously want the car right, plugged in computer and saved code was P0234 (overboosting). Had car fully serviced and problem was there before service just maybe not as frequent. Obviously thought of the obvious faults but there is no excessive smoke, checked egr and it has been blanked off, the whistle I thought from turbo was the "deleted dpf" the previous guy confirmed both these and a small remap to 185 to cope with the delete. The injectors are not outstanding by Audi, never get technicians just guys who can repeat part numbers. If I change gear early in 3-4th gear then car pulls pretty well up to 6th and have had her going fairly quick but of recent soon as I hit 3000 limp mode comes on. Check mirrors, clutch ↓, engine off , engine on, good to go.

I know its all too easy to blame the remap(the boy who I bought it off seems to say never had issue, surprised, remap was good- to be fair mpg was fantastic), its very jerky between 2000-2500rpm in lower gears, my instinct from previous experience of other cars feels like turbo related - is there anyway I can narrow down what it is with basic checks?

I know vanes are known for sticking. Dpf was prime suspect but now I know that wouldn't be it. Doubtful Egr as blanked, checked for any obvious leaks, tried additives like diesel magic, better quality fuel, the myth of revving the balls off it wont work! Audi adamant no recall for injectors.

Any help advice, suggestions I would be grateful, just don't get much free time so don't want to waste it looking in wrong areas. Relatively handy with tools. Also if anyone bought recon turbo, who they use and how much?

Thanks in advance

 

[WesternFreight]

You say dpf has been deleted have the insides actually been removed ie can u see where it has been welded back up ? I have same car and Audi replaced all injectors at 60 odd thousand miles free of charge, possibly under recall I can't remember I will have a look thru the paperwork for it.
I have heard of this problem before on something it turned out to be a 'turbo boost control solenoid' needed replacing, not sure if this car has one or not but defo seems turbo or actuator related to me, but I'm sure someone who knows more than me will be along soon, good luck.

 

[phil_w]

2 bottles of Forte Diesel Turbo Cleaner seems to have cured my overboost on same engine - sticking turbo vanes is usually the main culprit...


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[tut_gareth]

I'd be looking at the turbo boost (n75) solenoid or the air glow sensor.

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[tut_gareth]

....flow...

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[ZK3]

Thanks for the replies guys, already tried the forte when I did the service, didn't work straight away for me. The dpf makes a hollow whilstle (so it has been emptied and welded). I know the model is not in range for recall but don't have patience for speaking to Audi, not sure on Maf sensor but this kind of fault really is trial and error, trying restricting spending unnecessary funds to save for a honey comb grill!

Was adamant of trying the basics, so started with full service, flushed the coolant etc last week I do short journeys and rush a lot so instead of just starting up and going I left the car running for 1 min, let the oil heat up, I went for non supermarket fuel (in theory similar to using forte or other additives) and today I couldn't even force the light to come on, drove between 3000-4000rpm in low gears (Power!) To hopefully burn out any crud in the system (was unable to do this other day as at 3000 light would come on), no light some times slight hesitation but maybe its clutch or my driving not coping with the power from going 1.6 a3 petrol to 2.0 diesel! Guess it needs patience or maybe just placebo affect with good fuel, but so far so good.

Half the fun of a new car is finding out about the car and how to get the best out of it. Like the presumed turbo whistle was just a hollow Dpf sound that I am now quite fond of! Will report in couple of days of progress, got a long run on one of top gears favourite roads in the highlands over the weekends so car will get a good going over!

Happy Motoring!

 

[ZK3]

Surprisingly the car has had no issues over the weekend. Met a guy I was in school with who works for Forte now and says they sell a lot of the turbo cleaner with injector cleaner together, especially the local Audi garage!

Make of that what you will, but will probably try it out anyways myself!

 

[ZK3]

Just an update on this guys, as I hate when I read through and there is no update or closure on the issue.

The car did actually improve after changing away from tesco fuel and I also put in the forte injector cleaner and turbo cleaner. I always had a bit of hesitation so never used 4th to its potential.

Anyways last week it started doing it every journey, so I stripped down access to turbo and there was a bit of play, anyways I got a recon turbo, the old one was pretty clean but there was lots of play on the spindles. The car now pulls with so much power, 4th has the range I thought it should have and feels like a new car.

Morale of the story sometimes you just have to spend money to get the car right, you never know how the previous owner may have driven it!

 

[WesternFreight]

Ripper !!!

 

[RSTHRILLER]

Is that forte turbo cleaner any good do u put it I. With fuel

 

[ZK3]

Yeah it goes in the fuel, works along side with the injector cleaner. It never fixed my problem as my turbo was too far gone but what I will say was after putting in the turbo cleaner and injector cleaner together once removed the turbo wasn't as bad as I thought it was behaving so clearly works.