A3 tdi shaking
Discussion
Hi, there seems to be plenty of mechanical knowledge on here so instead of just reading through the forums I thought i'd post for once!
Ive got an A3 tdi 2.0 DSG, and under load the car sometimes has a slight wobble or shake that goes through the car. It happens at certain RPM's but seems to stop at high revs, and is worse lower down (between 1500- 2500 rpm).
Can anyone give me any ideas what this could be? I replaced a faulty injector which seems to have helped a bit, but the car still isn't running right. Sticky EGR, faulty MAF, faulty DMF have all been suggested.
To give more details for diagnosis:
- Car revs fine in neutral and is much better when you rev it, however its hard to hold the revs at 1500, and sometimes yuo can feel a slight wobble coming through the car.
- Idle is perfect, however when i've stopped at traffic the car seems to move up and down a little as if its got a big 5 litre V8 throbbing under the bonnet. Seems a little like a slight misfire.
- There are no dodgy sounds/rattles/squeeks etc.
- Problem is worse when in a low gear like 4th, or 5th in low revs and I put my foot down.
Any suggestions as to what this could be would be great, also any more info on faulty DMF's would be helpful too! Thanks in advance!
Ive got an A3 tdi 2.0 DSG, and under load the car sometimes has a slight wobble or shake that goes through the car. It happens at certain RPM's but seems to stop at high revs, and is worse lower down (between 1500- 2500 rpm).
Can anyone give me any ideas what this could be? I replaced a faulty injector which seems to have helped a bit, but the car still isn't running right. Sticky EGR, faulty MAF, faulty DMF have all been suggested.
To give more details for diagnosis:
- Car revs fine in neutral and is much better when you rev it, however its hard to hold the revs at 1500, and sometimes yuo can feel a slight wobble coming through the car.
- Idle is perfect, however when i've stopped at traffic the car seems to move up and down a little as if its got a big 5 litre V8 throbbing under the bonnet. Seems a little like a slight misfire.
- There are no dodgy sounds/rattles/squeeks etc.
- Problem is worse when in a low gear like 4th, or 5th in low revs and I put my foot down.
Any suggestions as to what this could be would be great, also any more info on faulty DMF's would be helpful too! Thanks in advance!
Its virtually imposible to pin point from your description. As it could be anything of the items you've already picked out.
IF it was DMF, it would be apparant when you rev in N, and eventaully would devolp into a more sever vibration, you would probably hear noises too. So it unlikely to be that.
If its happening at the same load and RPM in each gear then its engine related, if it happen at the same road speed (and its coinsidence that your in a particular gear/revs) at that speed will be wheel balance or road-wheel/suspention related.
EGR valves are mechnical/vacuum on A3 and alot less trouble that the electric ones, but can still stick and get gummed up.
SO, If its ok at full throttle and full load at high rpm, I would suggest the MAF is ok, But if your getting lots of black smoke at higher revs you could have a boost leak, that will cause your sort of symtoms, small hole in the intercooler or a slit boost pipe, for example.
A bit bit more input on exactly what it does and when might help.
I takeit you dont have to warning lights up and havent read the fault memory??
IF it was DMF, it would be apparant when you rev in N, and eventaully would devolp into a more sever vibration, you would probably hear noises too. So it unlikely to be that.
If its happening at the same load and RPM in each gear then its engine related, if it happen at the same road speed (and its coinsidence that your in a particular gear/revs) at that speed will be wheel balance or road-wheel/suspention related.
EGR valves are mechnical/vacuum on A3 and alot less trouble that the electric ones, but can still stick and get gummed up.
SO, If its ok at full throttle and full load at high rpm, I would suggest the MAF is ok, But if your getting lots of black smoke at higher revs you could have a boost leak, that will cause your sort of symtoms, small hole in the intercooler or a slit boost pipe, for example.
A bit bit more input on exactly what it does and when might help.
I takeit you dont have to warning lights up and havent read the fault memory??
Thanks for your reply!
Ok, so the first thing I done was have a diagnostics test carried out when I found the problem, it came up with 'cylinder 3 intermittent misfire'. I replaced the injector and then carried out another diagnostic test which confirmed the misfire was fixed (had live running data done, and the injector quantity wasnt stuck at 2.99 anymore!)
Anyway, that has helped the problem and the car has restored power and MAYBE improved the 'shaking', however it is definately still there. Now when my car is plugged into the diagnostic machine there are NO fault codes at all. I hoped the faulty injector was the cause of the shake.
I have removed and cleaned my MAF sensor, don't think thats improved anything.
In neutral at idle there is no shaking or noise at all, no shaking when revving in neutral either, but there is sometimes a very slight wobble if trying to hold the revs around 1500rpm. In fact, it is nearly impossible to hold my car at 1500rpm where the wobble is, it seems to want to sit above or below 1500, I cannot hold it there with the accelerator! All other revs are fine, it will happily hold at 3000rpm, 3500rpm for example.
When driving normally, there is usually no shaking or wobble at all. It seems to be worse the more load is placed on the engine, usually the wobble will carry on as long as I give it full throttle, in every gear and at any revs, it seems to be more related to how far down I push the accelerator.
I tried a little test by manually shifting to too high a gear and holding it there and then trying to accelerate and that makes it shake every time. (So i'll be doing 30mph in 5th gear and then staying in that gear under full acceleration)
So in summary all I can really say is that it seems more related to the load on the engine than anything else. Hope this gives you a bit more info to work with!
Thanks again, Ricky.
Ok, so the first thing I done was have a diagnostics test carried out when I found the problem, it came up with 'cylinder 3 intermittent misfire'. I replaced the injector and then carried out another diagnostic test which confirmed the misfire was fixed (had live running data done, and the injector quantity wasnt stuck at 2.99 anymore!)
Anyway, that has helped the problem and the car has restored power and MAYBE improved the 'shaking', however it is definately still there. Now when my car is plugged into the diagnostic machine there are NO fault codes at all. I hoped the faulty injector was the cause of the shake.
I have removed and cleaned my MAF sensor, don't think thats improved anything.
In neutral at idle there is no shaking or noise at all, no shaking when revving in neutral either, but there is sometimes a very slight wobble if trying to hold the revs around 1500rpm. In fact, it is nearly impossible to hold my car at 1500rpm where the wobble is, it seems to want to sit above or below 1500, I cannot hold it there with the accelerator! All other revs are fine, it will happily hold at 3000rpm, 3500rpm for example.
When driving normally, there is usually no shaking or wobble at all. It seems to be worse the more load is placed on the engine, usually the wobble will carry on as long as I give it full throttle, in every gear and at any revs, it seems to be more related to how far down I push the accelerator.
I tried a little test by manually shifting to too high a gear and holding it there and then trying to accelerate and that makes it shake every time. (So i'll be doing 30mph in 5th gear and then staying in that gear under full acceleration)
So in summary all I can really say is that it seems more related to the load on the engine than anything else. Hope this gives you a bit more info to work with!
Thanks again, Ricky.
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