surging please help

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millwrx

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i have a 1.8t quattro which has had ia fault for sometime now,when the car is driven hard it 9 times out of 10 starts to pulse at high revs in gear,just like the turbo is backing off and then coming back to life,you can even sometimes get it to missfire,car runs fine apart from that,have posted on here before but no one had a DEFO fix,i have tried things like coilpacks,n75 valve,dumpvalve,plugs,check for fault codes,and all the other checks,anyone had the same fault as mine and have found the fault??
cheers
 
Could it be an induction hose collapsing? Have you checked the condition of the intake hose fom the air box to the turbo?
 
Tastyterrier said:
Could it be an induction hose collapsing? Have you checked the condition of the intake hose fom the air box to the turbo?
Click to expand...
hi,did have a look,the pipe does feel weak but then so does the other ones,are you on about the one from the maf down to the metal turbo hose that fits onto the turbo?
 
Yeah, I think they can get a bit knackered after a while and collapse under high pressure induction
 
right will have a look 2moz then,might go for a silicone one
 
my mk4 golf was revo'd, and that surge'd. turned out to be faulty map!
 
Unplug the electrical connector to the N75. The turbo will run on wastegate pressure alone. If it still does it, then you may have a wastegate issue.

Also might be worth bypassing the N249 valve if you have one for the test as this can open the DV to release boost pressure.

This is one of those situations where you should log the engine with cag-com to see what the ignition timing and lambda say.
 
audi upgrades
I had the exact same issues and mine was evenutally diagnosed as a knackered fuel pump. Ran ok when not driven hard but when the turbo came on, it would missfire and come off and on... Not saying this is your problem but a possibility... Pop your hood after normal run, if the engine is unusually hot.. (like scorching like mine was!) it could indicate it's running lean and its a dodgy fuel pump. I changed all the major sensors on mine including the TIP, sparks, n75, coil packs MAF before a garage identified the problem. Also again yeah no error codes were logged which was even more frustrating!

Anyway best thing to do is get vag-com hooked up and get your mate to look at the logs while diriving.. Theres one for missfires can't remember what group number. Mine showed loads of missfires when on boost on all 4 cylinders when the turbo was coming on... HTH
 
cheers for repleys,just phoned audi to get a price on a fuel pump,£196 including the vat:(not a nice job to do either so the chap said,will try disconnecting the n75 valve and see if it still does it,did think it may have been fuel delivery,
 
mate im not saying for sure it's the fuel pump, it's a possibility... Hmm when I had mine changed aps charged roughly £200 to supply and fit a fuel pump, so maybe they come in seperate bits? Im not sure... Anyway get it checked out first before you splash out, or a proffesional opinion. If your near these guys take it to them: www.autops.co.uk

PS That's rubbish apparently it's quite striaght forward. You pull up the rear seats to access it and theres a few bolts to remove it.. Sure there's more of a procedure to it but it's not hard apparently! HATE SCUMMY AUDI sometimes, bet he said that to try and get you yo book it in there!!!!
 
mine has jolted around recently just on full load normally in 6th, earlier i was driving along and my boost presure kept droping off and then picking up again, really wiered woundered about the fuel pump for a while now as have seen many complaints about them
 
im a mechanic by trade so didnt think it would be too much of a job,might pop it out and have a look at it,anyone know where to get one cheaper if it is that???
 
just got a new genuine audi fuel pump for £60 delivered,bargain,will fit it and see if it cures it,
 
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