Discussion
hi chaps and chapettes
im new here and new to audi.i own a 2007 a4 1.9tdi 115bhp for the last 4 months.It has 65k on clock and so far loving it,apart from a little prob i am experiancing which im hoping some of you guys may be able to shed some light on or even just your thoughts.
It has a slight misfire,nothing major,when on light throttle,get it above 2000 revs especially in 2nd and its all singing and dancing.anything below it really is pretty cack,has no omph and really dont feel as smooth as when i first got it.also at 70mph it really dont feel like it wants to much.I am comparing this to the mondeo i traded in for but at the same time the mondy was a 115bhp with a bigger and heavier body.
My first thought was the MAF which i disconnected today with the engine running and the engine note didnt change at all.when i ever disconnected the mondys the engine whent nuts then cut out.Is this normal behaviour for these engines or should i have experianced the same as the mondeo when disconneting,is the MAF at fault or do you guys have any over thoughts.
thanx in advance
regards
nigel
im new here and new to audi.i own a 2007 a4 1.9tdi 115bhp for the last 4 months.It has 65k on clock and so far loving it,apart from a little prob i am experiancing which im hoping some of you guys may be able to shed some light on or even just your thoughts.
It has a slight misfire,nothing major,when on light throttle,get it above 2000 revs especially in 2nd and its all singing and dancing.anything below it really is pretty cack,has no omph and really dont feel as smooth as when i first got it.also at 70mph it really dont feel like it wants to much.I am comparing this to the mondeo i traded in for but at the same time the mondy was a 115bhp with a bigger and heavier body.
My first thought was the MAF which i disconnected today with the engine running and the engine note didnt change at all.when i ever disconnected the mondys the engine whent nuts then cut out.Is this normal behaviour for these engines or should i have experianced the same as the mondeo when disconneting,is the MAF at fault or do you guys have any over thoughts.
thanx in advance
regards
nigel
Easiest way to check the MAF sensor is to disconnect it and run the motor up. I'd be very surprised if it would be the MAF though. When faulty they cause an imbalance in the air/fuel mixture and wouldn't normally cause a misfire. Check the spill pipes first for cracks and leaks as the injectors could be breathing air in causing the misfire then check the basics.
Is the EML on? If it were a faulty injector it would normally run like a bag of nails and be lighting up the dash to let you know to stop driving it. The MAF don't always trigger the EML but generally if you disconnect it then run it up the road you'll get a boost of power to start then it'll go straight back into limp mode. Just turn the engine off and re-connect it then start again. You'll have the same symptoms if it is but it sounds like something more basic than that.
Also have a look at the vacuum advance pipes around the turbo actuator and all round the inlet plenum. They are approx 4mm in diameter and are prone to cracking which will allow too much air flowing and will adversely effect the MAP sensor in the plenum causing it to over fuel erratically.
Is the EML on? If it were a faulty injector it would normally run like a bag of nails and be lighting up the dash to let you know to stop driving it. The MAF don't always trigger the EML but generally if you disconnect it then run it up the road you'll get a boost of power to start then it'll go straight back into limp mode. Just turn the engine off and re-connect it then start again. You'll have the same symptoms if it is but it sounds like something more basic than that.
Also have a look at the vacuum advance pipes around the turbo actuator and all round the inlet plenum. They are approx 4mm in diameter and are prone to cracking which will allow too much air flowing and will adversely effect the MAP sensor in the plenum causing it to over fuel erratically.
This Audi uses the PD version of engine,the only real way to get a result is to have it plugged in to a diagnostic computor, if it is the 1.9 they are usaully reliable with only the wiring loom within the head breaking down (this supplys the injectors)if its 2.0 version then the injectors are very troublesome but VW/Audi have recently reduced their price by over 1/2, also check with your local Audi dealer about recalls on the injectors before you spend any money
Hi guys
Thank you for the replys
@adyady,no there is no EML light on,however i did manage to bypass the security torx screws and pull the MAF out for a bit of a clean up and the misfire seems to have settled a bit and i can certainly notice a small change in engine note now(more clicking and hissing)when disconecting which i certainly wasnt getting on original post,so maybe MAF or not.I do plan to go round the hoses as i have first hand experiance of blown hoses and the effects caused by this.my mondeo tdci started a slight misfire which took it about a year to get to a serious state,that was the EGR pipe.
is there any common hoses that fail on this engine to look out for?
It is indeed the 1.9 tdi pd engine.i have read about the wiring looms,but within the head!!!!!
Thank you for the replys
@adyady,no there is no EML light on,however i did manage to bypass the security torx screws and pull the MAF out for a bit of a clean up and the misfire seems to have settled a bit and i can certainly notice a small change in engine note now(more clicking and hissing)when disconecting which i certainly wasnt getting on original post,so maybe MAF or not.I do plan to go round the hoses as i have first hand experiance of blown hoses and the effects caused by this.my mondeo tdci started a slight misfire which took it about a year to get to a serious state,that was the EGR pipe.
is there any common hoses that fail on this engine to look out for?
It is indeed the 1.9 tdi pd engine.i have read about the wiring looms,but within the head!!!!!
Best advice I can give you in regard to the breathing side is check the intercooler pipes are expanding when revving the engine. It's possible that there could be a slight split in one of them causing the management to falter and overfuel but that really is a long shot.
The only one I had problems with was one that just cut out whilst driving and that was due to a dodgy injector which caused the ECU to kill the engine totally. We were told without fail that the injector loom is at fault and after a fiddly process and a high cost it did nothing. They are listed as having a wiring fault at the injectors inside the cam covers but to date I've never had one fail for that reason.
Thinking back, they also have a fuel pump relay fault in the fuse board which I've come across but again it would trigger the EML?!
It's a tough one this, but I'm still drawn to the MAF personally. What you can do is find out the resistance value across the MAF sensor and check it with a multi-meter, or see if you can find a donor one to test from a mate's car if you know anyone that could help rather than bite the bullet and buy one. Did you drive the car after disconnecting the MAF though or just let it idle?
The only one I had problems with was one that just cut out whilst driving and that was due to a dodgy injector which caused the ECU to kill the engine totally. We were told without fail that the injector loom is at fault and after a fiddly process and a high cost it did nothing. They are listed as having a wiring fault at the injectors inside the cam covers but to date I've never had one fail for that reason.
Thinking back, they also have a fuel pump relay fault in the fuse board which I've come across but again it would trigger the EML?!
It's a tough one this, but I'm still drawn to the MAF personally. What you can do is find out the resistance value across the MAF sensor and check it with a multi-meter, or see if you can find a donor one to test from a mate's car if you know anyone that could help rather than bite the bullet and buy one. Did you drive the car after disconnecting the MAF though or just let it idle?
Hi adyady
I did give it a short shot down the road with it disconected,and i mean a short drive,and it didnt really feel any different to it being connected,however not tried again since it was cleaned up.when i had it diconected tho the engine was at a cold temp,should it have been warmed up to temp first?
i plan to go round the hoses when time and daylight allow.
What i have forgoten mentioned tho,which happened on a couple of occasions,weather its linked to this prob or not,is that when i was coming of a roundabout it gave quite a violent jerk,then went when straightend up in a line no EML lights.Think this has happened 3 times max,last time being quite a while ago.
cheers
nigel
I did give it a short shot down the road with it disconected,and i mean a short drive,and it didnt really feel any different to it being connected,however not tried again since it was cleaned up.when i had it diconected tho the engine was at a cold temp,should it have been warmed up to temp first?
i plan to go round the hoses when time and daylight allow.
What i have forgoten mentioned tho,which happened on a couple of occasions,weather its linked to this prob or not,is that when i was coming of a roundabout it gave quite a violent jerk,then went when straightend up in a line no EML lights.Think this has happened 3 times max,last time being quite a while ago.
cheers
nigel
Has the correct oil grade been used when servicing.
I have seen this when people disregard the correct oil grade (PD oil or Longlife 3)
When incorrect oil is used it can wear the cam lobes & followers. It doesn't bring on a light and it misfires.
Worth getting cam cover off & checking followers for excessive wear, sounds like this could be your fault.
I have seen this when people disregard the correct oil grade (PD oil or Longlife 3)
When incorrect oil is used it can wear the cam lobes & followers. It doesn't bring on a light and it misfires.
Worth getting cam cover off & checking followers for excessive wear, sounds like this could be your fault.
Nigel, if you run it up the road with it disconnected and it made no difference I personally think you've found the answer. It makes no odds whether the car is running warm or cold for the MAF, that's half the job of the sensor itself. Think logically not mechanically, if it is disconnected and makes no difference to the performance does it mean that it is working when re-connected?
The purpose of the MAF is to correct air flow in relation to fuel which is controlled by the ECU. One of the main sensors for the ECU to work off of is the........ MAF sensor.
The last comment about the oil is correct in theory but in 20 years I've never had a car misfire because of excessive cam wear apart from in highly tuned engines that have very little tolerance. It's a possibility but highly unlikely. On nearly every make and model where a MAF sensor is fitted it seldom activates the EML or records as a DTC. If it were my money, I'd be looking at a new one but it's your car and your money.
Good advice from a mechanic in the know is to source one from Euro Car parts if you do replace one. They are a main dealer agent with Bosche and I'd be very surprised if it's maker is any one different. VW / AUDI do not make these parts but will gladly sell you one with their mark up on it. DO NOT get one from a cheaper source as they are cheap for a good reason. They don't work. There was a posting last month about a Vauxhall combo where I suggested the same and he bought a cheap one off Ebay, guess what? It didn't work. He got a cheaper genuine Bosche one from Euro's and was delighted that it fixed the problem.
The purpose of the MAF is to correct air flow in relation to fuel which is controlled by the ECU. One of the main sensors for the ECU to work off of is the........ MAF sensor.
The last comment about the oil is correct in theory but in 20 years I've never had a car misfire because of excessive cam wear apart from in highly tuned engines that have very little tolerance. It's a possibility but highly unlikely. On nearly every make and model where a MAF sensor is fitted it seldom activates the EML or records as a DTC. If it were my money, I'd be looking at a new one but it's your car and your money.
Good advice from a mechanic in the know is to source one from Euro Car parts if you do replace one. They are a main dealer agent with Bosche and I'd be very surprised if it's maker is any one different. VW / AUDI do not make these parts but will gladly sell you one with their mark up on it. DO NOT get one from a cheaper source as they are cheap for a good reason. They don't work. There was a posting last month about a Vauxhall combo where I suggested the same and he bought a cheap one off Ebay, guess what? It didn't work. He got a cheaper genuine Bosche one from Euro's and was delighted that it fixed the problem.
adyady1066 said:
The last comment about the oil is correct in theory but in 20 years I've never had a car misfire because of excessive cam wear apart from in highly tuned engines that have very little tolerance. It's a possibility but highly unlikely. On nearly every make and model where a MAF sensor is fitted it seldom activates the EML or records as a DTC. If it were my money, I'd be looking at a new one but it's your car and your money.
As an ex VW I have seen this fault a few times, & is not highly unlikely. I was giving advice on another course of action should it not be the MAF. I would find someone who can check the MAF readings or swap one from another car rather than buying one & it not cure it. If it does cure it then you know you're not wasting your money on a MAF.perky85 said:
As an ex VW I have seen this fault a few times, & is not highly unlikely. I was giving advice on another course of action should it not be the MAF. I would find someone who can check the MAF readings or swap one from another car rather than buying one & it not cure it. If it does cure it then you know you're not wasting your money on a MAF.
No criticism meant there at all. I did suggest in an earlier post to check the resistance across the sensor or swap it to check but by disconnecting it you'd normally get an instant and noticeable change in the performance. That's how I check most of them on the theory that if it's connected and working by disconnecting it you'd know straight away. I had a TT that had been into Audi 3 times and they couldn't figure out the fault. They pointed at the MAP as it was the only thing that listed as a DTC yet it was randomly happening. All I did was run it up the road with the MAF off and viola! New one and it ran like a dream. Even the dealership were surprised. The problem nowadays is there's too much electric control but if you break it down to what the symptoms are like the old days before scanners etc then you'll have half a chance. Scanners as you well know only tell you what it thinks, not the cure. Yes, the car may be running rich but my question is why? Diagnostic machines never give you that answer, they point you in the right direction and the dealers will change everything at your cost. It's how they make their money after all. 
There are a couple of comments on this topic which is causing a little confusion.
1.The 1.9pd engine will still run with a injector failed, but the 2.0pd will not run as the ecu shuts down the engine with one injector failed and wont start unless it is disconnected from the circuit.The injector wiring loom for both the 1.9 and 2.0 run inside the cylinder head and are both prone to failure.
2.The camshafts wear massivly and it will still run but noisely and rough even appears to be on 3 1/2 cylinders and will be under powered.The type of oil and poor intervals and high milage all cause this issue.
3. The MAF does give issues but by reading measured block values on a road test will give you the correct info to identify the cause, also the price from TPS(vw) or over the counter at Euro/GSF can be similar but you get 100%correct part and 2year warranty from VW
4.By disconnecting the MAF on older TDI would cause ecu to go to its default value which would make it run better IF the MAF was faulty,this does not work on more modern TDI`s
5.By revving the engine whilst squeezing the boost pipe to see if it expands will give you a indication that the turbo is boosting but that is a basic check, again you would need to see the measured block values under load in 3rd gear to see if correct boost is achieved.
1.The 1.9pd engine will still run with a injector failed, but the 2.0pd will not run as the ecu shuts down the engine with one injector failed and wont start unless it is disconnected from the circuit.The injector wiring loom for both the 1.9 and 2.0 run inside the cylinder head and are both prone to failure.
2.The camshafts wear massivly and it will still run but noisely and rough even appears to be on 3 1/2 cylinders and will be under powered.The type of oil and poor intervals and high milage all cause this issue.
3. The MAF does give issues but by reading measured block values on a road test will give you the correct info to identify the cause, also the price from TPS(vw) or over the counter at Euro/GSF can be similar but you get 100%correct part and 2year warranty from VW
4.By disconnecting the MAF on older TDI would cause ecu to go to its default value which would make it run better IF the MAF was faulty,this does not work on more modern TDI`s
5.By revving the engine whilst squeezing the boost pipe to see if it expands will give you a indication that the turbo is boosting but that is a basic check, again you would need to see the measured block values under load in 3rd gear to see if correct boost is achieved.
hi all
just to give a quick update,i have disconected the MAF and have given it a good drive around the holiday park that the in-laws stay at,the verdict,certainly no worse,if not a bit better in the way it seemed more eager and willing to wanna go.The EML eventually came on but did not send it into limp mode and did not make things any worse with it on.
i can understand some comments regarding the oil and worn cams but surely that would be a permanant fault and not intermittant.
Im,for the mean time,gonna assume the MAF is breaking down which is causing the misfire/hesitation and will source one my local euro car parts shortly after xmas,when my funds start returning.
regards
nigel
just to give a quick update,i have disconected the MAF and have given it a good drive around the holiday park that the in-laws stay at,the verdict,certainly no worse,if not a bit better in the way it seemed more eager and willing to wanna go.The EML eventually came on but did not send it into limp mode and did not make things any worse with it on.
i can understand some comments regarding the oil and worn cams but surely that would be a permanant fault and not intermittant.
Im,for the mean time,gonna assume the MAF is breaking down which is causing the misfire/hesitation and will source one my local euro car parts shortly after xmas,when my funds start returning.
regards
nigel
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