Engine Vibration at specific rev range

[everson38]

Hey guys,

Currently have my sister 1.2 TSI Seat Ibiza 62plate for the week to inspect it whilst she's away.

I have noticed with the engine running and sitting stationary, if you rev the car upto 1500 rpm, the car is fine, but when you take your foot of the throttle and let the needle drop back down, when it hits about 1100 rpm, you can feel the car shake for a moment until it's back settled at 800rpm .

I have tested this (carefully) whilst driving and putting the car in neutral and coasting, but cannot feel anything then really, seems to be at a stationary point.

Any ideas?

Thanks in advance.

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[RUM4MO]

Just a couple of comments, firstly, the engine's controller gets fed with road speed information, so it is possible for its revs V throttle demand will be different when the car is rolling along or freewheeling than it does when the car is stationary, secondly, it might just be the engine's controller avoiding a stall situation and trying to "capture" the design idle RPM.

Unless you have driven a similar car that is not showing this trait it would be tricky to pin it down as an issue.

 

[everson38]

Just a couple of comments, firstly, the engine's controller gets fed with road speed information, so it is possible for its revs V throttle demand will be different when the car is rolling along or freewheeling than it does when the car is stationary, secondly, it might just be the engine's controller avoiding a stall situation and trying to "capture" the design idle RPM.

Unless you have driven a similar car that is not showing this trait it would be tricky to pin it down as an issue.

Yeah possibly, I'm hoping it's nothing serious, but never known this issue an any other car. But I have just had someone test it whilst I watch and I can see the engine mount looks worn, the engine is definitely slopping and you can shake it with your one hand and the person us rocked about in the car. When it hits this point the engine does move, so maybe a gear mount issue.

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[RUM4MO]

Remember is a few conditions have been met, when the engine is reving above a certain RPM, when you release the throttle pedal, the fuelling is cut off, and then brought back on in time to avoid engine stalling, when in gear and on the over run the car's momentum dampens that stumbling out also the rate of dropping revs is slower.