help! A4 diesel - loss of power/acceleration

help! A4 diesel - loss of power/acceleration

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ritch

Original Poster:

527 posts

188 months

Wednesday 4th August 2010
quotequote all
this is for a mate who knows nothing about cars!

Audi A4 2.0 TDi (PD138bhp engine) apparently has a loss of power, stuttering and accasional soot cloud are the symptoms.
foot to the floor acceleration creeps up very slowly instead of rather briskly.
noises like letting air out a balloon (honest thats his description!!!!) are heard too.

He has managed to limp the car the last 10 miles into work and is worried about the drive home (30 miles). Its now booked into the dealers later this week.

Any ideas on this and whether further driving could cause more serious damage? I'm guesstimating that some sort of airhose / pipe connected to the turbo has burst/split/came loose?

thanks for any help/advice - I'll pass it on.

pugwash4x4

7,529 posts

222 months

Wednesday 4th August 2010
quotequote all
leaking turbo hose somewhere- explains the whistling and the overfuelling (black smoke)

ritch

Original Poster:

527 posts

188 months

Wednesday 4th August 2010
quotequote all
thanks for the superfast response!!! any ideas as to whether this could cause further damage if he drives it home?

Vidal Baboon

9,074 posts

216 months

Wednesday 4th August 2010
quotequote all
PITA these 2.0TDis!

Mines gone into limp mode twice- both for overboosting and the had faults with the injector wiring loom.

When he turns it off, it should reset itself.

Apparently something called an N75 valve can play up & also the vanes on the turbo stick which causes the overboosting. I've ran mine on Shell V-Power Diesel not the low sulphur city diesel crap which apparently causes the sooting up, not done it since.

BTW the wooshing noise happens on mine too- sounds like a recirculating valve directing pressurised air back into the airbox.

If it's making noises like that, then the first suggestions in this thread would be my guess too.

Edited by Vidal Baboon on Wednesday 4th August 13:51

pugwash4x4

7,529 posts

222 months

Wednesday 4th August 2010
quotequote all
vidal could be more on the money mind- i'm more of a mechanical injectoin chappy rather than all this modern newfangled electronic stuff.

Blocked EGR is another possibility- quite cheap and easy to fix at least.

Personally i wouldn't drive it like that- tonnes of soot means the engine isn't burning all the diesel going into it, this causes exhaust temps to rise massively, and can easily shoot past the point where you weld a cylinder to the bore. If you're lucky you just destroy your turbo.

Would only drive it to remove it from an unsafe position (ie motorway)

james_tigerwoods

16,287 posts

198 months

Wednesday 4th August 2010
quotequote all
Could be the air mass meter - sounds not unlike a problem I had a few years back...

sparkesp

298 posts

196 months

Wednesday 4th August 2010
quotequote all
Air mass meter for me too.... symptoms were, put your foot down....wait... stutter....wait....cough, splutter and SOOT then off we go!

ritch

Original Poster:

527 posts

188 months

Wednesday 4th August 2010
quotequote all
cant see it be the AFM due to the air noises and the fact there is no acceleration at all.

AFAIK the mileage is around 30k and mostly motorway.

pugwash4x4

7,529 posts

222 months

Wednesday 4th August 2010
quotequote all
AFM can usually be checked by unplugging it- a lot of systems default to a standard map- if that improves matters than you have isolated a potential fault

ritch

Original Poster:

527 posts

188 months

Thursday 5th August 2010
quotequote all
its in the garage now - I'll report back what their diagnosis / fix is when he hears back.

ritch

Original Poster:

527 posts

188 months

Thursday 5th August 2010
quotequote all
it was an intercooler pipe came loose / off. apparently due to some oil residue through the pipework / intercooler. all fixed now and matey is happy.

pugwash4x4

7,529 posts

222 months

Thursday 5th August 2010
quotequote all
ahh get me- first post with the right diagnosis- that' doesn't happen very often biggrinbiggrin

flakeypaul

436 posts

191 months

Thursday 5th August 2010
quotequote all
My Renault dci engine did this - was the pipe from the turbo to the intercooler (had split) - symptoms exactly as above, then the car went into limp home mode for good measure so no turbo at all! Didn't help that I was doing a not inconsiderable number of leptons on the m62 at the time! The guy I was overtaking wasn't happy!