Please help, vibration when accelerating from 1800-2800 rpm

[cip82]

I have Audi A6 C7 , 2 litre,177 bhp, manual gearbox 160000 miles.
I have a vibration when accelerating from 1800-2800 rpm in every gear. In the summer I changed the left driveshaft because mechanic said it was a little bend and the cv joint near the gearbox had play so changed but no change in vibration. I had aftermarket rims and he said vibration from spigot rings.put this ones also no change.
I took my injectors to check them and 1sr injector 0.25, 2nd 0.35, 3rd 0.36, 4th 0.40, I dont know if they were good because they didnt have injection parameters for my car. He said to change first injector,after the vibration wasnt feel so hard. We put the computer to see the numbers: 3 and 4 injectors close to 0, 1st had +0.58 ,second -0.52 so I think the second is compensating the first one. Ordered new injector will change tomorow.
Until then I did a test with a mechanic and he said is definitely dual mass flywheel. ANY OPINIONS IN THAT ??

[Rob69]

Is it only when driving in gear or is it there when in neutral at 1800-2800 rpm ? does it change at all if you press the clutch in ?
Sounds like it could be flywheel related - is that the original flywheel and clutch at that mileage ?

[Golf TD]

It sounds like a dual mass flywheel

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[cip82]

It sounds like a dual mass flywheel

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Thank you for your opinion Golf TD, I asked around and they said the dual mass flywheel should vibrate also when you dont drive ,idling, but mine acts normal when idling.I still think have a problem with injectors. Recently I changed one injector and vibration reduced by half, 2 days ago I changed another injector and engine runs a little bit strange, noise like tractor, also when accelerating doesn't acelerate normal. I will check again all injector s and see after that.
Anyone knows what are thr parameters for mine ??? Like how much is the variation of the injector s ?? +/- For example mine has if I remember +0.21, +0.21, +0.48, -0.54

[cip82]

Hi Rob69, I already reply to your question , but I dont know why it didn't appear. Vibration is only in gear when accelerating. No vibration when idling.

[Rob69]

Those injector values look ok, range given in my vcds measuring blocks group 13, is -2.8 to +2.8. Faulty injectors would be more like a misfire, low power, fuel consumption, smoking, rather than vibration. Any fault codes logged?Do you hit a flat spot at 1800 rpm and notice exhaust smoke? You say it doesn't accelerate normally and you're changing injectors, are these new or reconditioned injectors. If you think its injector related you need better diagnostics rather than just changing parts. I Still think it could be DM flywheel related though.

[cip82]

Thank you for opinion and information Rob69. I dont hit a black spot at 18000revs. It is normal acceleration but from around 1800 revs starts to vibrate.. no exhaut smoke, no misfire,only a little bit of low power maybe 10-15 bhp less that when I bought , and high consumption. I used to averaging in town 32mpg but 6-7 monts ago averaging only 25mpg,than I started to look at injectors.No faults codes. Injectors are rebuild ,new injector nozzle,new valve but no change in vibration or consumption. Last summer changed Egr valve because spontaneous error and cleaned intake manifold because of carbon mixed with oil deposits.I will have a look one more time at injectors or somebody tell me to check engine and gearbox dumpers. Could that give vibrations ??? If not I will change dmf and clutch, very expensive but I cant drive with that vibration.Regeneration of dpf is every 130-140 miles, I am doing 95% town trips.Once per year go in europe on german autobahn.Start stop function doesnt work anymore. I had a check with vcds but no errors yet.When I press clutch to drive off I have to accelerate a little bit more because when I release clutch will start to vibrate so compensate thru acceleration. Hope that helps. Thank you so much for help.

[Rob69]

Looking at the age of the car (5 years max) i doubt your gearbox or engine mounts are shot and if you have the solenoid operated mounts they should throw up a fault code.
I think you may have two problems here, and should really get some good diagnostics done - check dpf soot loading, injection manifold pressure etc for reduced mpg. Think you may also need replacement injectors coding to the engine in CR system ? Can't help thinking an injection problem would be logging a code whereas a mechanical flywheel fault is appearing at same revs/ engine load and torque though. You are also saying you have to play the clutch and revs to minimise vibrations, points to clutch / dmf as cause of vibration to me.

[niall campbell]

if the car is sitting in driveway, do you feel the vibrations at those revs ?

if you feel the car vibrating at those revs in the driveway, does pushing the clutch down help ?

[cip82]

Hi, no vibrations in idle when sitting on driveway, no vibrations if I stay on driveway and accelerate ,no vibrations if press clutch only when I drive and I am in 2,3,4,5,6 gear and accelerate. Vibration starts around 1800 rpm until 2600-2800rpm. If I accelerate constantly lets say at around 2000 rpm doesn't vibrate only when accelerate.

[cip82]

Ok. I will check dpf sooting and injection pressure manifold . Regarding injectors coding in CR system is the same thing when you replace an injector and take the code of new injector and replaced it with the old code ???(reprogramming or recoding ) or is something else ??? When I replace injector/s mechanic did the coding or reprogramming of new injector/s. One mechanic said that because is no vibration when idling there is no DMF problem but from what I seen on youtube and read on net could be DMF but need to be 100% sure because its a lot of money and need to replace also the clutch.

[cip82]

Just come back with an update.
Yesterday I replaced clutch + dmf. Big improvement with clutch but the vibration is still there so DMF wasnt at fault. At least I replace it and its new. The only think that cause my vibration its at injectors. Before I replaced one injector my vibration was double so I will check injectors and see what I find. I will keep updating.

[RichieP77]

Hi there, I'm new to the forum but have almost exactly the same problem as you here. I am interested to see how you got on.
I have an 2005 A4 2.0tdi. I recently bought the car (foolishly in hindsight) in a private sale. Car has done 110k miles, FSH with lots of receipts etc. The car is perfect for me in every way apart from a strong vibration when accelerating between 1600-2100 rpm.
If I accelerate slowly then it's hardly noticeable, but if overtaking or accelerating quickly then the vibration comes through the gearstick (shakes badly) and seats of the car. Until past about 2100 rpm them it settles down. I can still feel it slightly after 2100 but only because I know it's there, passengers can not anymore.
I've changed the DMF and clutch which two mechanics thought it would be but to no avail. Vibration still exactly the same. However the old DMF was completely gone, seized solid, mechanic had to smash it off to remove it??? (I also ended up having the head skimmed, timing belt and water pump changed - total bill of £1700).
So I have spent a fortune on it and still have the vibration.
I did notice it on test drive but agreed a £400 price reduction so was fairly happy the DMF replacement would solve the problem. Alas not.
I am now taking the car to a local fuel injection place to have the injectors checked on Monday. Hoping they find something as I've had it at 4 places and no one can pin point where the problem is coming from.
I've had both drive shafts off and new one out on which also made no difference, so I have my old ones back on (was able to return the new ones thankfully as they made no difference).
I've recently had the car in a long journey and other than this vibration the car drove superbly on motorway cruising happily at 70-80mph without a flicker - but it's getting there that's causing me the problem!
Any help or advice would be greatly appreciated as I am now in a desperate state with it.
Hope you got sorted with yours.
Thanks very much...

[cip82]

Hi there. Still didnt sort it out. Recently I replaced engine supports. One of the supports had two metal pieces broken one has the liquid out and the one under the gearbox was completely gone. I replaced all 3 noticed a big improvement but vibration still there. The same if accelerate smoother no vibration but if I put my foot down it will shake . I have my car in service for head rebuil and other staff plus drife shaft replacement hopefully it will help. If any news will let you know.

[RichieP77]

Thanks for replying. Yes please let me know how you get on with drive shafts. Made no difference to mine but had to try to rule out.
Next step for me i think is injector test and clean. The place today quoted around £250 to do that. But cant guarantee it's causing the problem. Not sure whether to do it or not really, might have to wait until after Christmas!
I will keep checking to see if you have any luck... cheers.

[RichieP77]

Hi again, just thought I'd add that I have solved my annoying vibration at long last - it was a faulty injector.
Had all four taken out, cleaned and pressure tested. No.4 was fine, no.2 and no.3 were at about 95%, but no.1 was a write off - only giving about 60% fuel under load. So I had that replaced and it now drives like a train. Cost me about £600 for all that mind, but it has ended my doubts about the car, and put my mind at rest from constantly wondering what it was or what might happen next. What a nightmare I have had with it. Hope no one had to go through that! Hope this helps with anyone else who has a similar problem. Cheers