Audi A3 1.9 TDI 110 BHP (ASV) - Sluggish when cold

[deaconj999]

Hi Folks, I have a problem with my good old Audi which was now reached 209K miles and until now was running like new.

A few weeks ago I noticed that as a drive out began fine at low revs under 30mph. When I then got to the dual carriageway about 3 mins away and upped the revs and speed as the engine got to about 2000 - 2500 revs the car would jolt and got into what may be explained as a sort of limp home mode until I switched the ignition off and the back on and the problem would seem to correct itself with the car driving normally.

This continued until 2 weeks ago when the problem of power loss started to happen at low revs and at speeds of under 30 mph. In addition, turning the engine on and off didn't seem to make a difference.

So, over the last 3 days I disconnected the MAF sensor and ran the car but it didn't seem to make a difference.

I resorted to cleaning the intakes after the MAF sensor with this:10K BOOST DIESEL ENGINE POWER RESTORER

Halfords | 10K Boost Diesel Engine Power Restorer

I also added this to the fuel tank to clean the injectors and fuel lines : COMMA DIESEL MAGIC

Halfords | Comma Diesel Magic 400ml

and finally cleaned the MAF sensor removed from the car with: ELECTRICAL CONTACT CLEANER

Halfords | Halfords Electrical Contact Cleaner 400ml

Job was completed yesterday afternoon, coldish but not freezing UK winter day, about 4'C (37ish 'F maybe) and took it for a run, it worked fine and seemed to have corrected the loss of power at all speeds, town roads and motorways.

I also recall, the radio has gone into safe mode but the battery doesn't seem to have gone flat at all, which is puzzling.

Positives are: tick over is fine constant and stable around 950 rpm stays steady, no misfiring detected, no coloured exhaust emissions at all, not even before, only blue smoke whilst decoking with 10K. Fuel consuption average dropped from 50.4 to 50.3 on display and only by 0.1 over the least week.

PROBLEM :
Now, this morning, frost on the ground, wife starts car and drives 4 miles to work, right from the beginning it behaved as though it was in a tractor pull and wouldn't go over 20mph, similar to what it was doing before all this treatment. Turning on and off ignition made no difference.

Don't want to take it to a garage to have some silly code telling me wrong info, which will be costly, but thinking that MAF needs replacing. I understand this so far, but N75, vacuum hoses, EGR ? I have got a Haynes manual but not very good at locating these parts in the engine compartment, I only know roughly where they site in front of the driver, UK side !!!

Any help would be greatly appreciated.

Joe

[OddBallBoy]

Sounds like it could be the turbo actuator sticking. Loads of threads on here - search for sticking VNT.
It's well worth changing all your vacuum pipes to rule them out as the original rubber ones do perish over time. Really cheap and easy to do - seem to recall for most VAG Tdi's, there are a mixture of 3 & 5mm pipes but have a look in your engine bay or at other threads to check. You can buy silicon tubing of eBay etc vey cheaply, probably do the whole job for not much more than £10. When you do it, be very methodical, only do one pipe at a time to ensure you get all the connections right and use the pipe you take off to cut the new one to the right length.
Finally, to be sure of what the problem is, you really do need a code read. Have a look at the VCDS locations thread to see if there is someone local who may be able to help you out. But bear in mind, a code read can still only give an indication of the problem - I think it likely your fault code will be related to the Manifold Air Pressure sensor but it seems fairly rare that it is actually the sensor itself at fault.
Good luck

PS - I'm no expert, this is all stuff I've picked up from reading other threads.

[mjrplan9]

Sounds like it could be the turbo actuator sticking. Loads of threads on here - search for sticking VNT.
It's well worth changing all your vacuum pipes to rule them out as the original rubber ones do perish over time. Really cheap and easy to do - seem to recall for most VAG Tdi's, there are a mixture of 3 & 5mm pipes but have a look in your engine bay or at other threads to check. You can buy silicon tubing of eBay etc vey cheaply, probably do the whole job for not much more than £10. When you do it, be very methodical, only do one pipe at a time to ensure you get all the connections right and use the pipe you take off to cut the new one to the right length.
Finally, to be sure of what the problem is, you really do need a code read. Have a look at the VCDS locations thread to see if there is someone local who may be able to help you out. But bear in mind, a code read can still only give an indication of the problem - I think it likely your fault code will be related to the Manifold Air Pressure sensor but it seems fairly rare that it is actually the sensor itself at fault.
Good luck

PS - I'm no expert, this is all stuff I've picked up from reading other threads.

do u have the glow plug light constantly flashing on your dash?if u have a code reader handy that would help.maf issue wouldnt keep your speed down that slow.usually makes u hit 2000rpm max.could be injection pump,happened to me a while back.cut out and went into a safe mode where my throttle was disengaged from use.the car would slowly speed itself and all i could do was change gear,weird experiance.look for the glow plug light on dash.if it starts flashing when engine ticks over u got an engine management issue ok

[deaconj999]

Hi, not had any dash warning lights at all, only once when unplugging maf sensor, yellow coil type symbol came on. that was it. I wonder if it is the turbo or the egr or vacuum pipes, it is in need of an oil change, oil is black, bot good and probably doesn't help as I think the turbo uses engine oil ?

[mjrplan9]

Hi, not had any dash warning lights at all, only once when unplugging maf sensor, yellow coil type symbol came on. that was it. I wonder if it is the turbo or the egr or vacuum pipes, it is in need of an oil change, oil is black, bot good and probably doesn't help as I think the turbo uses engine oil ?

oil in diesel goes black right and quick anyway.yeah turbo vane spools on a film of oil.if.doesnt sound like a turbo issue.u should get it put on a dagnostic machine,any garage that does that will be able to show u and clear codes should help,especially when you might have a maf fault code on there.for tthe sake of 20-30 quid i'd do that first man.least u'll know whats been stored on the ecu that might give a clue as to why your cars been playing up ok

[deaconj999]

Last few days the car has dropped in MPg to 50.1 from 50.4 moths ago it was 54.3 ish. Left for a while engine cold drive off and it is sometimes flat with absolutely no acceleration accelerator half way down or all way down and it seems to jolt forward and then run normally, but this can happen and sometimes take a lot longer. Today it ran perfect no flat loss of accleration, parked up for 5 mins after 10 minute drive and it was flat again reaching no more than 2k revs. More often than not it feels as though it kind of clears its throat and then accelerates (jolts) forward, then at over 3k revs it can still seem to give up accelerating an goes flat again. I have also noticed tiny fizzy bubble in the clear fuel line, so I have ordered a new fuel filter, I certainly haven;t drained the water out of it with the valve at the bottom of the filter. Could this be part of the problem?

[mjrplan9]

Last few days the car has dropped in MPg to 50.1 from 50.4 moths ago it was 54.3 ish. Left for a while engine cold drive off and it is sometimes flat with absolutely no acceleration accelerator half way down or all way down and it seems to jolt forward and then run normally, but this can happen and sometimes take a lot longer. Today it ran perfect no flat loss of accleration, parked up for 5 mins after 10 minute drive and it was flat again reaching no more than 2k revs. More often than not it feels as though it kind of clears its throat and then accelerates (jolts) forward, then at over 3k revs it can still seem to give up accelerating an goes flat again. I have also noticed tiny fizzy bubble in the clear fuel line, so I have ordered a new fuel filter, I certainly haven;t drained the water out of it with the valve at the bottom of the filter. Could this be part of the problem?

bubbles in line is common,filter change wouldnt be a bad thing.sounds like an air intake issue.check for any splits on your intake pipe from your air filter by the maf sensor.again get it hooked upto a code reader.ebay get u a decent one for 40£ autel vag a gud job.reads and clears stored codes.saved me a fortune doing that...good investment mate..i'd do that