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2.7 hesitant vibration
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2ilent8cho   
Tue Jul 17 2018, 07:59am
Joined: May 11 2016
Member No: #2626
Location: Stoke on Trent
 Not really sure how to describe this but hopefully if somebody else has had this they will understand.

I can be driving along at say a constant 45mph and the car feels shakey from the power, it feels like hesitation of engine power going on and off continually. If i go into manual mode and drop the car a gear it goes away. If i floor the car power comes on very smoothly and it this feeling goes away. The rev line's stay stable when its doing this shakey feeling so my gut is telling me its more to do with the gearbox than the engine.

Is this sounding familiar to anyone else with a 2.7 V6 ? Car is currently on 109,000 miles and i see no sign of any gear box oil changes , could it be something as simple as needing a few changes?
C6Dave   
Tue Jul 17 2018, 10:31am

Joined: Oct 01 2009
Member No: #1
Location: Northumberland
 Definitely worth giving a fluid change a try as it could be dirt in the fluid causing sticking in the valve chest.
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Hattershaun   
Tue Jul 17 2018, 09:07pm
Joined: Dec 19 2010
Member No: #320
Location: Bedfordshire, UK
 It could also be the torque converter starting to break up. I've driven a C6 with this symptom.
It was as if you were driving over a rumble strip at the edge of a motorway.
2ilent8cho   
Wed Jul 18 2018, 08:50am
Joined: May 11 2016
Member No: #2626
Location: Stoke on Trent
 Yes it feels a little like that but without the noise. I get the feeling this might be expensive.
arconell3   
Wed Jul 18 2018, 10:16am
Joined: Jun 28 2012
Member No: #922
Location: Kalkar
2ilent8cho wrote ...

Not really sure how to describe this but hopefully if somebody else has had this they will understand.

I can be driving along at say a constant 45mph and the car feels shakey from the power, it feels like hesitation of engine power going on and off continually. If i go into manual mode and drop the car a gear it goes away. If i floor the car power comes on very smoothly and it this feeling goes away. The rev line's stay stable when its doing this shakey feeling so my gut is telling me its more to do with the gearbox than the engine.

Is this sounding familiar to anyone else with a 2.7 V6 ? Car is currently on 109,000 miles and i see no sign of any gear box oil changes , could it be something as simple as needing a few changes?


You say the revs stay stable when this happens? That is somewhat strange, because in that case and without the car speed changing either, (I assume the cruise control is engaged) how can you tell there is a power hesitation?

However, these power hesitations at just under 2000 RPM and at constant speed are well known. They are mostly caused by a dirty air intake tract (air filter, LMM's, butterfly housing). That causes a change in the power/RPM/accelerator-position matrix values being just outside the values acceptable by the gearbox controller, and resulting in a rhythmic opening and closing of the torque-converter lock-up.

Clean or replace those parts and it should be OK again.

Regards, Robert
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2ilent8cho   
Wed Jul 18 2018, 11:19am
Joined: May 11 2016
Member No: #2626
Location: Stoke on Trent
arconell3 wrote ...

2ilent8cho wrote ...

Not really sure how to describe this but hopefully if somebody else has had this they will understand.

I can be driving along at say a constant 45mph and the car feels shakey from the power, it feels like hesitation of engine power going on and off continually. If i go into manual mode and drop the car a gear it goes away. If i floor the car power comes on very smoothly and it this feeling goes away. The rev line's stay stable when its doing this shakey feeling so my gut is telling me its more to do with the gearbox than the engine.

Is this sounding familiar to anyone else with a 2.7 V6 ? Car is currently on 109,000 miles and i see no sign of any gear box oil changes , could it be something as simple as needing a few changes?


You say the revs stay stable when this happens? That is somewhat strange, because in that case and without the car speed changing either, (I assume the cruise control is engaged) how can you tell there is a power hesitation?



It just feels like engine power wanting to go forward then coming off, then back on, a bit like when you are about to stall in a manual how the power still lurches you forward but extremely subtle version of this.

Its just one of those things thats hard to describe without feeling it.
arconell3   
Wed Jul 18 2018, 11:54am
Joined: Jun 28 2012
Member No: #922
Location: Kalkar
 Yes that describes the phenomena I was referring to pretty well. Except, as I mentioned, you would see the revs changing every time it happens, ever so slightly, but they do.

Regards, Robert
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