Engine miss and slight shimmering under acceleration - and general stuff at 60k serv.

[Silver Caravelle]

Hi all,

I mentioned on another posting re steering wobble regarding some issues I have had with my 2008 TDi Multi. In essence Engine miss at approx 1400 rpm, occasional hesitation and slight shimmering under acceleration (which I thought might have been slight play in the right hand front wheel). After 60K service, new fuel filter, oil change etc did not alter these characteristics - although slight play in the front wheel hub is not really there any more. It was also noted the right front strut bearing is a little noisy but not enough to warrant replacement yet.

Also not fault codes detected by dealer.

Also investigated at the 60k service was an oil leak, which was identified as weeping from the air take plastic pipe as it joins the turbo inlet. Apparently after time because of heat the join expands and oil mist etc leaks. As it is a hard pipe, putting a tightening clamp on it does not sort it out and replacement is the only option. I wondered if this might cause the engine miss with unmetered air, but feel it would need to be split or something for this to occur.

So after the service, I have done over 2000 kms of solid highway travel to Sydney from Melbourne and back and copping 46 degrees (yes 46 degrees!) just out of Wodonga on the highway. But no end of warm running, Italian tune ups has sorted the engine miss and slight shimmering under acceleration. In fact it was stumbling more so at times.

When I got back, I plugged my V-checker in, and still no fault codes. No turbo intercooler pipe leaks. VNT linkage moves as expected. Auto shifts fine.

I went back to the dealer and discussed further. As not fault codes, a thought might be the 'DMF' might have very slight play (yes I know this is and auto!!). The dealer wondered if it might be this, giving the impression of an engine miss, when in fact it might be a pulsing feel. He said the autos don't have a fly wheel, but a DMF filled with grease. I thought these were only on manuals?? Perhaps he got confused that I had the DSG box.

I suggested it may be a slightly blocked injector causing slight engine balance issues and miss at 1400 RPM. The dealer suggested trying some injector cleaner first. So I trotted down to Super Cheap and purchased the Liqui Moly concentrate/deep fuel cleaner and put into the fuel take (not the purge stuff as I was nervous trying to unplug the fuel filter inlet and return without breaking them).

The current status is that after about 100K of working the engine so far, it feels much smoother, and engine miss at 1400 rpm and shimmering under acceleration is less noticeable. I will see how it is as the fuel is used. The directions indicate at about 200Ks it should be quite noticeable.

So hopefully, this will solve the issues. I will keep you posted.

Regards,

Scott

[Skoda VW]

I had a DMF go in my Skoda Scout 6spd manual at around 13,000km's. It gave the impression that it was missing below 1500rpm, but it was vibration caused by the faulty DMF.

[Silver Caravelle]

I had a DMF go in my Skoda Scout 6spd manual at around 13,000km's. It gave the impression that it was missing below 1500rpm, but it was vibration caused by the faulty DMF.

Hi Skoda VW,

Thanks for the response. Mine (Tiptronic) Auto ) is Ok at idle and below 1400 RPM. I am not convinced the auto has a DMF, unless it has a 'DMF like flywheel' that can 'loosen up' a bit to cause similar characteristics of a deteriorating DMF. Hoping it is an injector that will unblock with the Liqui Moly.

Regards,

Scott

[Sunny43.5]

Hi Silver Caravelle , I think after seeing the whole of our Tiptronic in pieces recently I can say there is no DMF as they run a torque converter . I might be wrong but is the shimmering you talk about would you describe it as a shuddering feel ? If so I can only tell you that if that's the case then you will need to get the auto checked as the dealers will not do anything as VW tell them NOT to open them up . Our slipping shuddering had been going on for some time and was caused by a partially blocked fluid filter in the bottom of the auto's sump if it gets blocked it will restrict oil flow and then the clutch packs will slip causing first shuddering then eventually slipping after that its all over red rover . If I had know 4 years ago that they could be serviced I would have been spared the anguish we went through recently .

[Silver Caravelle]

Hi Silver Caravelle , I think after seeing the whole of our Tiptronic in pieces recently I can say there is no DMF as they run a torque converter . I might be wrong but is the shimmering you talk about would you describe it as a shuddering feel ? If so I can only tell you that if that's the case then you will need to get the auto checked as the dealers will not do anything as VW tell them NOT to open them up . Our slipping shuddering had been going on for some time and was caused by a partially blocked fluid filter in the bottom of the auto's sump if it gets blocked it will restrict oil flow and then the clutch packs will slip causing first shuddering then eventually slipping after that its all over red rover . If I had know 4 years ago that they could be serviced I would have been spared the anguish we went through recently .

Hi Howard,

Thanks for the response.

Auto appears fine; no slippage and shifts fine. No fault codes either.

Probably two separate things going on:

1. Engine miss at approx 1400 RPM, noticed when revving in neutral and when cruising at 60km/h in 5th as the 'sweet spot'. Hopefully the Liqui Moly injector cleaner will assist reducing this.

2. Slight shimmering under acceleration. Autos have a flywheel/flex plate and the torque converter takes up against the flex plate when in drive/reverse. Perhaps it is the flex plate that has some play in it leading to the slight shimmering?

On a other note has anybody noticed under full acceleration, vehicle veers very slightly to the right? Tyres in good condition and equal pressures.

Thanks,

Scott

[Sunny43.5]

The slight shimmering you describe does it happen when the engine is under load ?, as ours started to "shimmer" which is like a shudder when we go up a steep climb to our house . We have to slow down to almost a stop before turning into the street then accelerate up a steep hill for 300 metres during the middle of the climb you would feel this slight shudder . I am only trying to help you eliminate a possible cause , the shudder will not show up on a fault code as ours was serviced by VW several times and it never showed up on the diagnostics even when it was shuddering badly at the end when it failed .
The veering is probably just torque steer under full blown acceleration I have noticed the same effect its trait that front wheel drives have and remember there is TCS which would be reacting at the same time maybe .

[Silver Caravelle]

The slight shimmering you describe does it happen when the engine is under load ?, as ours started to "shimmer" which is like a shudder when we go up a steep climb to our house . We have to slow down to almost a stop before turning into the street then accelerate up a steep hill for 300 metres during the middle of the climb you would feel this slight shudder . I am only trying to help you eliminate a possible cause , the shudder will not show up on a fault code as ours was serviced by VW several times and it never showed up on the diagnostics even when it was shuddering badly at the end when it failed .
The veering is probably just torque steer under full blown acceleration I have noticed the same effect its trait that front wheel drives have and remember there is TCS which would be reacting at the same time maybe .

Hi Howard,

Thanks again. Very slight Shimmer is felt just taking off normally under light acceleration. If I can reduce the miss fire, I will then be able to know for sure if it is related to this or separate. Engine mounts are also fine.

Re slight veering to the right. Can't say it was always there, but has been recently. Possibly related to new tyres replaced a few months ago? No wheel alignment was done as there was no uneven tyre wear on previous tyres.

Thanks,

Scott

[Splitn]

I had a similar shimmering type feel under accelerating in my 2005 T5 128 kw tdi 4-Motion 6sp manual.
Found to be the gates coupling "free wheel" on alternator.
Did feel like the engine had a miss at times.

[SGG]

Another shimmy issue here .... After our Oettinger ECU upgrade (Manual 2007 T5 1.9 turbo diesel with 30,000kms) which neither my mechanic nor Oettinger nor another VW mechanic upon inquiry have figured out, at around 1800-1900rpm while accelerating there is a faint sporadic shudder from the engine bay. It doesn't always happen and its not a major shudder but it does happen and it is reasonably consistent. I don't think it was there before the ECU upgrade. It only happens at this point in the rev range. There are no error codes and everything else is peachy in the vans performance

[Silver Caravelle]

Thanks all for your replies.

Splitn: is there a straight forward way to inspect if the "free wheel" on alternator is suspect?

SGG; in relation to faint sporadic shudder from the engine bay at around 1800-1900rpm, another mystery! Makes you wonder of there is some sort of cylinder balance issue, or perhaps more torque at that particular rev range creating some additional harmonic vibration. All theories on my part.

Regards,

Scott