TDI90: occassional wobles, shaking, vibrates at idle
- Thread starter Olerype
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audifan
A2OC Donor
The whole idea of DMF is to reduce low rpm vibration!! As I have said you can change the injector loom - they do have an extremely hard life soaked in engine oil, hot and cold cycles. It is not unknown for the connectors to work loose on the injectors, but the way I look at it you have already exposed the loom why not go ahead and replace it. The shaking could be making a iffy connector loose making the shaking worse. As the engine warms up the connection could be getting better or worse difficult to say. If you keep the idle over say 1000rpm there is no further issue even when the engine is warmed up?
Made some readings in VCDS. The car was started after being stationary for 15 hours. Car was stationary at all times (gear stick in free)
1) First start: some deviation between injectors (cyl. 3 tries to compenstate cyl 1). Slight shaking. Shaking gets worse if dis-engaging clutch-pedal and the peak deviations are up to 2,4 mg/str but varies alot
2) after 5-10 minutes warmup, the car can idle perfectly without skaing regardless clutchpedal. Zero deviations reflects this, and from the scope the curves just smoothens out
3) if being idling, it is possible to provoke shaking again either by
a) engaging or disengaging clutch pedal
b) quick push on gaspedal to increase rpm (1200rpm) and thereafter let the engine idle again (950rpm)
From below cyl 2. tries to compensate cyl 1 and 3
The car is booked in at Audi for replacement of DMF Wednesday next week, but this really puzzles me.
1) First start: some deviation between injectors (cyl. 3 tries to compenstate cyl 1). Slight shaking. Shaking gets worse if dis-engaging clutch-pedal and the peak deviations are up to 2,4 mg/str but varies alot
2) after 5-10 minutes warmup, the car can idle perfectly without skaing regardless clutchpedal. Zero deviations reflects this, and from the scope the curves just smoothens out
3) if being idling, it is possible to provoke shaking again either by
a) engaging or disengaging clutch pedal
b) quick push on gaspedal to increase rpm (1200rpm) and thereafter let the engine idle again (950rpm)
From below cyl 2. tries to compensate cyl 1 and 3
The car is booked in at Audi for replacement of DMF Wednesday next week, but this really puzzles me.
audisean89
Member
on thing you could try if I missed It is pop the cover off unclip the injector low get a really small flat head and bend the pins back but don't go mad, I had it on my a3 vibrating away did that and problem solved
Status:
1) DMF/clutch replaced. The old DMF had a slack of 80-100mm while the new one 30-40mm. Total different car now. BUT the car still shakes in 4. and 5. gear going uphill, or pulling a trailer (ie load). The shaking gets worse when flooring it, and disappears when stepping off the gas
2) there is slightly more vibrations when going downhill motorbraking than with gearbox in free (car increasing speed). The vibrations would be considered as normal, but it just interesting that there is a difference
3) I imagine, but not sure, but it seems that shaking gets worse after eg 20 minutes drive
4) crosschecked the injector deviations with the other 1.4TDI AMF, and those deviations are more or less identical. And all deviations are within spec.
5) checked the torsion value as well. That value peaks at 2,2 degrees but still within spec (the AMF is at 0 in comparison). I may try to improve this
6) does anyone know what the resistance values should be if ohming the injector loom while connected to the injectors? Ie just disconnect the plug without removing the rocker cover
7) the third engine hydraulic mount seems to be collapsed, so is considering to have that replaced just to rule out the engine mounts (the car shakes because the engine mounts can not absorb the shaking and the gearbox mount touches the car frame)
1) DMF/clutch replaced. The old DMF had a slack of 80-100mm while the new one 30-40mm. Total different car now. BUT the car still shakes in 4. and 5. gear going uphill, or pulling a trailer (ie load). The shaking gets worse when flooring it, and disappears when stepping off the gas
2) there is slightly more vibrations when going downhill motorbraking than with gearbox in free (car increasing speed). The vibrations would be considered as normal, but it just interesting that there is a difference
3) I imagine, but not sure, but it seems that shaking gets worse after eg 20 minutes drive
4) crosschecked the injector deviations with the other 1.4TDI AMF, and those deviations are more or less identical. And all deviations are within spec.
5) checked the torsion value as well. That value peaks at 2,2 degrees but still within spec (the AMF is at 0 in comparison). I may try to improve this
6) does anyone know what the resistance values should be if ohming the injector loom while connected to the injectors? Ie just disconnect the plug without removing the rocker cover
7) the third engine hydraulic mount seems to be collapsed, so is considering to have that replaced just to rule out the engine mounts (the car shakes because the engine mounts can not absorb the shaking and the gearbox mount touches the car frame)
Menno
A2OC Donor
Didn't read the complete topic, but if it's not suggested already; Please check inboard CV joints. They tend to give vibration when worn, especially under load and/or uphill in higher gears......
Here's mine, severe vibration going uphill under load.
Sometimes it was gone, the needle bearing (remaining parts of it) didn't blocked something occasionally...
Here's mine, severe vibration going uphill under load.
Sometimes it was gone, the needle bearing (remaining parts of it) didn't blocked something occasionally...
Last edited:
Yes, driveshaft is also a possibility since the shaking at standstill now seems to have disappeared after replacing the DMF. From engine bay I can see that at least the inner CV gearbox side is spraying grease even the boot seems fine.
I think I have multiple problems on this car
I think I have multiple problems on this car
I have not checked the injectors so I do not know. But the car is just fine now, and the deviations were within spec so not concerned.
To summerize - what is replaced on the car:
1) all three motor mounts
2) new LUK DMF and clutch
3) new driveshafts
The engine mounts fixed the motor sagging but this was probably not the main issue.
With the new DMF the car drives very differently. Before I could hardly drive below 2krpm. Now just fine even if it mostly likes to be in the high revs. It also killed the shaking of motor at standstill
The new driveshafts fixed the crazy shaking going uphill 4. and 5. gear.
dj_efk
A2OC Donor
You’ve clearly solved multiple issues in one hit. It must be a much nicer car to drive now, the 90 should pull cleanly from 1600 rpm at n any gear.
Well done and enjoy the results.
Yes thanks!
It starts to gently pull from 1200rpm now, anything below 2000rpm was uncomfortable in the past with the old DMF.
I was about to go that route about injectors, wire loom and oil chain tensioners and is so glad I did not. Very confusing when the problems happened.
I could however probably saved a few bucks not replacing all motor mounts.
It starts to gently pull from 1200rpm now, anything below 2000rpm was uncomfortable in the past with the old DMF.
I was about to go that route about injectors, wire loom and oil chain tensioners and is so glad I did not. Very confusing when the problems happened.
I could however probably saved a few bucks not replacing all motor mounts.
dj_efk
A2OC Donor
Sure you know and this isn’t your normal MO but I wouldnt put your new DMF under undue strain by trying to get it to pull from that low revs even gently.
Oil chain - what’s your mileage and has it been done? Consider getting it done at the next cambelt change if you’re on more than 120k miles
Oil chain - what’s your mileage and has it been done? Consider getting it done at the next cambelt change if you’re on more than 120k miles
Yes totally agree about DMF. Full throttle first at 2krpm!
Car done soon 200kkm; will be considered next timing belt at about 260kkm.