SMOKEY A4 19 TDI

[BrendanMC]

OK guys, plenty of food for thought, but her is the Audi Specialist's view, for anyone else with this problem.
the MAP sensor which does live in the back pipe from the intercooler does actually read the manifold pressure and sends the signal via the ECU, which controls the wastegate, ie the boost. But what i'm told is that the fault i got is due to either a faulty MAP sensor, giving false readings ot that the wastegate is sticking. if it's the sensor then fair enough £80 or so. and substitution is the only way to really find out. If it's the waste gate sticking then it could be a one off or the start of the end. Seemingly if you can get a hold of a vacuum gage or similar device and check the action, in both directions, of the wastegate, it has to be smooth without any binding or sticking. And you can clean the MAP sensor. So i'll start with the electrical cleaner, and let you guys know how it goes. OK!

[BrendanMC]

Hi, I'm back. Ok here's the deal, I cleaned and checked all of the vacuum pipes, cleanned the Air Intake temp sensor and pipe. Used an electrical tester on both the EGR solinoid and the Turbo acuator valves. Vacuum tested the EGR Valve and the Turbo variable wastegate valve and all is well. The valve is not sticky and action is smooth in both directions, yet once at 2400 revs for 4 or 5 seconds you can feel the turbo go and the car stays in limp mode till the ignition is switched off. It's got me baffled, and it runs great below those revs, use the gearbox and it's fast and smooth as silk, approx 47 mpg too.
What is this?????????????
OH just for info, I don't know where the smoke has gone, i haven't seen a puff since it started this limp modse carry on. I wonder if this is a clue as to what is wrong.
Help.

[madfella65]

BrendanMC - exact problem that i had order of events below;
Driving home one night (actually xmas eve!) passing a car ~50mph and..... nothing no power - the car felt like driving a 1.0 Diesel (non-turbo!)
Stopped the car and started it again - drove like mad - no problems... until about 5 minutes later same prob no power - left it over xmas - then took it to a mate who is a vw/audi mech found a vacuum pipe which had been cut (didnt really explain the intermittent problem - happy enough to fix it and hope it was the solution!)
About 2 days later (not much driving done over xmas as you can imagine) problem arises again.
Back to the drawing board (intermittent pressure on the vacuum pipe to the turbo) - mate happened to have an N75 (small solenoid valve that bolts on to front of engine) changed it - not really much difference - put the old one back is it wasnt faulty - then to the MAF (he also has an A4 B5 one) swapped with his car - no difference
B5 MAP wouldnt fit from his car - so brother has a 150BHP golf tdi - swapped with his - cha ching! solved - car never went as well!!!!
Also - i think there is another sensor right down on the top of the intercooler which could be your prob - this is another sensor that feeds air temp or something back to ECU

Hope this helps you get to the bottom of your prob - if you know anyone with the same car as you MAP & MAF sensors take 30 seconds to swap (two star head screws)
Can post pics of their location if you need it?

[BrendanMC]

Thanks for that.
I ordered a new MAF last night, i thought it might be that especially as the car went from quite smokey to really clean but cutting out.
I'll cross my fingures and post the result.
Thanks again.
PS is the N75 valve the black and white one that only allows vacuum in one direction. I've heard it mentioned so many times yet haven't seen this elusive character.
Brendan

[VW Techniker]

There is the;

MAP - Manifold Air pressure - this senses the boost pressure
MAF - Manifold Air Flow - This senses the amount of air entering the engine.

Maf is attached to the airbox and I think the MAP sensor is on the black boost pipe which runs across the back top of the engine. But the fault code reader does say its the MAP sensor.

If the fault is intermittent then its unlikely to be the actual turbo as its a mechanical device and if its broke, its broke.

MAP - Manifold Absolute Pressure
MAF - Mass Air Flow

[madfella65]

MAF.JPG Maf

MAP.JPG Map

PG-V6-N75-s.jpg N75 (one on your car is black and white and located on the front of the engine quite close to the A/C compressor)

[Dave Avant]

MAP - Manifold Absolute Pressure
MAF - Mass Air Flow

[andyroo]

Hi Folks
My A4 1.9 130 smoked very badly under hard acceleration just fitted a K&N panel filter and wonderous things NO smoke at all now (no gains in performance but that does not surprise) maybe thats all thats needed!!
Always pays to try the cheap solutions first!!

[Dave Avant]

Hi Folks
My A4 1.9 130 smoked very badly under hard acceleration just fitted a K&N panel filter and wonderous things NO smoke at all now (no gains in performance but that does not surprise) maybe thats all thats needed!!
Always pays to try the cheap solutions first!!

I've fitted a K&N panel filter (washed it first to get rid of excess oil, so not to foul the MAF) and disconnected the EGR, no smoke at all.

[andyroo]

Hi
Washing the filter defeats the object. The oil is there for the muck to stick too. If there's no oil there's no stiction and therefore no filtering of fine particles only big lumps!!