1.8 Turbo Problems
Discussion
Dear all
I have a 2000 Audi A3 1.8 T Sport that has developed a stuttering hesitation when you accelerate hard in 3rd, 4th or 5th. It doesnt really feel like a proper miss fire and can be intermitant.
99% of the time under normal driving it is absolutly fine but occasionally (only happened twice, both times on the same day), it does it in every gear with low revs.
Any suggestions would be greatly appreciated.
It has done 60k miles and has a full Audi history. I have heard that Audi dont change the fuel filter as a serviceable item so was wondering if it could be that.
Anyones help would be much appreciated?
Cheers
Stephen
Also does anyone know a good specialist in the south Derbyshire/Midlands area?
I have a 2000 Audi A3 1.8 T Sport that has developed a stuttering hesitation when you accelerate hard in 3rd, 4th or 5th. It doesnt really feel like a proper miss fire and can be intermitant.
99% of the time under normal driving it is absolutly fine but occasionally (only happened twice, both times on the same day), it does it in every gear with low revs.
Any suggestions would be greatly appreciated.
It has done 60k miles and has a full Audi history. I have heard that Audi dont change the fuel filter as a serviceable item so was wondering if it could be that.
Anyones help would be much appreciated?
Cheers
Stephen
Also does anyone know a good specialist in the south Derbyshire/Midlands area?
Could be any number of things - MAF, recirc valve, N75 valve, coil packs, loose turbo hoses - plus others could cause hesitation. Best bet to start with is find somebody locally with VAGcom or another diag tool to see if the controller has anything obvious logged as a fault. The problems mentioned above are easy and cheap to sort but it could be something else.
dain bramaged said:
most common probs on most audi and vw is air flow meters on the air filter housing pipe
Id go with that. I had a 2001 1.8 t-sport A4 for 4 years. Had it chipped by a well known tuner (Ive no idea if this is related to the problem) and the car ate air flow meters (well, 4 in 4 years) and produced the hesitation the original poster describes.
HTH
Edited by FUBAR on Friday 27th October 14:04
Thanks for all the suggestions.
It has had a VAG COM diagnostics check when in went into Audi and they said they couldnt find any faults.
I spoke to one specialist that said the throttle butterflies do get gunged up over time and need a good clean out so might try that as well.
I will go and have a play with the plug on the ignition amplfier tomorrow and just hope I havent got to spend too much money on it!
Watch this space....
Stephen
P.S. Im begining to think I have a bit of a dog of a car as this morning the LH sidelight was on when I left the house, off when I picked a friend up and back on again when I got to work.
And, the light behind the light switch is flashing as if it has a loose connection!
I bought an Audi thinking with German build quality it would be faultless!
It has had a VAG COM diagnostics check when in went into Audi and they said they couldnt find any faults.
I spoke to one specialist that said the throttle butterflies do get gunged up over time and need a good clean out so might try that as well.
I will go and have a play with the plug on the ignition amplfier tomorrow and just hope I havent got to spend too much money on it!
Watch this space....
Stephen
P.S. Im begining to think I have a bit of a dog of a car as this morning the LH sidelight was on when I left the house, off when I picked a friend up and back on again when I got to work.
And, the light behind the light switch is flashing as if it has a loose connection!
I bought an Audi thinking with German build quality it would be faultless!
shollis said:
P.S. Im begining to think I have a bit of a dog of a car as this morning the LH sidelight was on when I left the house, off when I picked a friend up and back on again when I got to work.
And, the light behind the light switch is flashing as if it has a loose connection!
!
And, the light behind the light switch is flashing as if it has a loose connection!
!
Halloween is just round the corner
Do you have problems starting from cold?
Try the coolant temperature sensor it sits to the right of the engine, and is a common component to fail.
Part number is 059 919 501. Specify you want the green top one. should be around 26 quid. cheap fix to start with as it will eventually go wrong.
HTH
Andy
Try the coolant temperature sensor it sits to the right of the engine, and is a common component to fail.
Part number is 059 919 501. Specify you want the green top one. should be around 26 quid. cheap fix to start with as it will eventually go wrong.
HTH
Andy
PROBLEM SOLVED 
(I hope!!)
I unplugged and re-connected the amp plug on top of the airbox at the weekend and it seems to have cured it (touchwood!)
Thanks guys!
Andy
Funny you should mention it but I changed the temp coolant sensor (for a green pin one) last tuesday after the car was hesitating the previous weekend more than it ever has done.
The gauge always went from 0 to 90 and then back again since I got the car but didnt think changing it would have that much of an effect. As it turns out when I changed the temp sender there was a noticable improvment but the hesitation was still there.
Before I changed the temp sender the engine management light would occasionally come on for a few days, and then go off again! As soon as i changed the sender unit the light went off but then completly unexpectedly it came back on yesterday has hasnt gone off again. I think it must be related to a different problem so need to get it plugged into VAG com (any one got it?).
As for the side light issue I think there is a loose connection some where as when you waggle the wire (very technical!) on the back of the light unit the bulb flickers on and off. I thought it was European law that you should be able to change the bulb at the side of the road but typically it doesnt look like you can get the back cover off cause the battery is in the way!
Cheers
Stephen
Note to anyone changing the temp sender - It is an easy job once you have found it (it is in the water hose that runs along the left hand (battery)side of the engine, you can get at it if you remove the 2 plastic panels but do wait till the engine has cooled down totally as the water does retain a lot of heat (Speaking from experiance!!)
(I hope!!) I unplugged and re-connected the amp plug on top of the airbox at the weekend and it seems to have cured it (touchwood!)
Thanks guys!
Andy
Funny you should mention it but I changed the temp coolant sensor (for a green pin one) last tuesday after the car was hesitating the previous weekend more than it ever has done.
The gauge always went from 0 to 90 and then back again since I got the car but didnt think changing it would have that much of an effect. As it turns out when I changed the temp sender there was a noticable improvment but the hesitation was still there.
Before I changed the temp sender the engine management light would occasionally come on for a few days, and then go off again! As soon as i changed the sender unit the light went off but then completly unexpectedly it came back on yesterday has hasnt gone off again. I think it must be related to a different problem so need to get it plugged into VAG com (any one got it?).
As for the side light issue I think there is a loose connection some where as when you waggle the wire (very technical!) on the back of the light unit the bulb flickers on and off. I thought it was European law that you should be able to change the bulb at the side of the road but typically it doesnt look like you can get the back cover off cause the battery is in the way!
Cheers
Stephen
Note to anyone changing the temp sender - It is an easy job once you have found it (it is in the water hose that runs along the left hand (battery)side of the engine, you can get at it if you remove the 2 plastic panels but do wait till the engine has cooled down totally as the water does retain a lot of heat (Speaking from experiance!!)
shollis said:
. I thought it was European law that you should be able to change the bulb at the side of the road but typically it doesnt look like you can get the back cover off cause the battery is in the way!
Last time I rocked up at an Audi dealer with a blown rear light bulb (as I couldnt work out how the light unit came out/access to) I was told they can sell me a new bulb or replace it for me, but they couldnt/wouldnt show me how it was done
. IIRC a new bulb cost me £40
(but I think I now know how its done 
)They will try and charge for anything. I went in to borrow the radio removal tools and they said I would have to book it in and pay the minimum rate of £45 plus vat for for 30 mins work for them to do it!!
I 'should' be able to just remove the battery clamp and tilt the battery back to get the back cover off but it is a pain.
I know that on the Bentley Conti GT prototypes it was an engine out job to change a headlight bulb as the W12 was a bit of a tight fit!!
I 'should' be able to just remove the battery clamp and tilt the battery back to get the back cover off but it is a pain.
I know that on the Bentley Conti GT prototypes it was an engine out job to change a headlight bulb
as the W12 was a bit of a tight fit!!Had the same thing on my wifes and took an age to diagnose the problem as the ignition amp. Gave it a good clean up and it's been fine since...... Unfortunately I don't think the A3 is the most reliable of cars on the road. We've had a myriad of elec gremlins with ours but the £1k bill for a gearbox re-build at 78k miles was a bitter pill to swallow. I've had VAG cars for years but am increasingly becoming dis-illusioned with the brand.
Im beginning to get a bit fed up of it. I thought I had solved the problem by cleaning the ignition amp but it still hesitates and I have noticed over the last few days that it seems to be worse in the wet. It could be just coincidence but another thought....
Im trying to get my VAG.COM working to do a diagnostic check but cant get that working either! The engine management light was on but has now gone off again. I am making an assumption that the problems are linked but need to get it checked out.
Stephen (becoming a very disgruntled Audi owner
)
Im trying to get my VAG.COM working to do a diagnostic check but cant get that working either! The engine management light was on but has now gone off again. I am making an assumption that the problems are linked but need to get it checked out.
Stephen (becoming a very disgruntled Audi owner
)I'm still betting on the Air Mass Meter for the hesitation. Even if VAG COM doesn't show it. Sometimes you can test whether it is this unit by simply unplugging the electrical connection on it (on the inlet piping after the air filter). If its the AMM then it will probably drive OK now (but not be as efficient/environmentally friendly as it should until you plug back in and/or replace the unit.
Not sure about the warning light.
Not sure about the warning light.
Another new development….
Has anyone heard of the N249 valve? Apparently it controls the dump valve and is supplied air pressure to operate by the black air tank reservoir mounted on the right hands side of the engine bay. Having this reservoir tank allows there to be pressure available for the ECU to open the dump valve whenever is deems necessary.
Well, the black air tank on my car makes a constant ticking noise (I assumed this to be a relay or pump operating?). Interestingly, when I unplug the air mass flow meter, this ticking noise stops! So, I have come up with a possible scenario that this N249 valve is faulty, so occasionally it decides to relieve the engine of all its boost at the most inopportune moments, leaving me with a hesitation…
The N249 valve could be linked to the air mass flow meter, which is why the ticking noise stops when disconnected. I am tempted to try and drive it with the air mass flow meter disconnected but am worried that it might cause damage to the engine by over boosting or something like that.
Using the vast wealth of knowledge on this forum, does this sound possible?
Also, any ideas what an N75 is?
I also need to get VAG.COM on it to see what that throws up but getting that to work is a whole other issue!!
Regards
Stephen
Has anyone heard of the N249 valve? Apparently it controls the dump valve and is supplied air pressure to operate by the black air tank reservoir mounted on the right hands side of the engine bay. Having this reservoir tank allows there to be pressure available for the ECU to open the dump valve whenever is deems necessary.
Well, the black air tank on my car makes a constant ticking noise (I assumed this to be a relay or pump operating?). Interestingly, when I unplug the air mass flow meter, this ticking noise stops! So, I have come up with a possible scenario that this N249 valve is faulty, so occasionally it decides to relieve the engine of all its boost at the most inopportune moments, leaving me with a hesitation…
The N249 valve could be linked to the air mass flow meter, which is why the ticking noise stops when disconnected. I am tempted to try and drive it with the air mass flow meter disconnected but am worried that it might cause damage to the engine by over boosting or something like that.
Using the vast wealth of knowledge on this forum, does this sound possible?
Also, any ideas what an N75 is?
I also need to get VAG.COM on it to see what that throws up but getting that to work is a whole other issue!!
Regards
Stephen
The N75 is the diverter valve - get a replacement from Forge motorsports. We fitted a chrome Bailey one to our TT after 2,000 miles from new as the OEM part was crap. I'm not sure how this is connected to the AMM. I do know you can drive the car with the AMM disconnected though (but offer no warranty!).
I suggest nipping over to a VW specific forum like www.tt-forum.co.uk. There are people there who can give you a really quick answer.
I suggest nipping over to a VW specific forum like www.tt-forum.co.uk. There are people there who can give you a really quick answer.
shollis said:
Well, the black air tank on my car makes a constant ticking noise (I assumed this to be a relay or pump operating?). Interestingly, when I unplug the air mass flow meter, this ticking noise stops! So, I have come up with a possible scenario that this N249 valve is faulty, so occasionally it decides to relieve the engine of all its boost at the most inopportune moments, leaving me with a hesitation…
The N249 valve could be linked to the air mass flow meter, which is why the ticking noise stops when disconnected. I am tempted to try and drive it with the air mass flow meter disconnected but am worried that it might cause damage to the engine by over boosting or something like that.
The black tank is a fuel vapour recirculation valve, and is supposed to make the ticking. It's an annoying noise, isn't it?? It recycles unburnt fuel vapours and puts them back into the cumbustion chambers. I'm sure that when the MAF is disconnected, the ECU detects this, and runs the learned values of air mass at varying throttle positions and loads, and uses these to calculate how much fuel you need. If your MAF is fubard, it will be giving the wrong numbers to the ECU and knocking/under or over-fuelling will be the result.
I know that the N249 valve is connected to the boost/vacuum circuit and can cause wierd boosting issues. I don't know where it's located, but the ticking noise is supposed to be there, and it may stop because the ECU doesn't know how much air it is getting so isn't sure to recycle the fumes into the engine and possibly create knocking.
You will not do any damgae to the engine running it with the MAF disconnected, but long term it may cause rich or lean running, so don't do it for too long, just long enough to establish it's faulty.
The N75 is a boost control valve, told by the ECU how much boost to allow the turbo, there is no way to tell if it is faulty apart from swapping with another. It is connected to the diverter valve and with the ECU co-ordinates the opening and closing of the turbo wastegate.
The diverter valve re directs the pressurised air from the intercooler side of the compressor to the air intake side when the throttle is closed, keeping the turbo spinning. BTW if your valve is standard and makes a sound on gear change similar to Group B rally cars, it's fubar'd. I thought this was cool, but it's not! Lol
I'm really not trying to teach you to suck eggs, just get a broader understanding of the whole system!
What's up with your vag-com? I've got the shareware version and it works, may be able to help you get yours going.
BTW I have a 98 A3 1.8T, and have gone through a load of weird faults of late most, if not all, were assisted by the good people on www.audi-sport.net , www.vag20v.net , and oddly as it may seem, www.uk-mkivs.net - for golfs, but they're the same engines, and the knowledge base over there is huge!
Anyway let me know how you get on with the car and computer!!
Andy
Edited by LaSarthe&Back on Tuesday 14th November 21:53
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