Shaking issue from the front of the car

kzslt1

ex-Alfaholic
Jun 11, 2014
22
0
Budapest - Hungary
Hi guys,

My car (Seat Leon MK1 1.4 AHW - 180 k kilometers - 112 k miles on the clock) has developed a new problem...

The problem is a bit complex, I started to notice some shaking from the front of the car lately (~1 month ago), but not on the steering wheel. 3 weeks ago I went abroad and the roads were in horrible state, I destroyed my front tyres. So I bought a new ones, the wheels were balanced etc. But next morning there was no idle (still abroad on summer vacation). Luckily i had my laptop with me and the diagnostic software showed that the throttle actuator (G60 or V60?) has failed and the Lambda signal was too low.
When I was coming back the shaking was still there but I thought that it was because of the faulty throttle body and lambda sensor. I bought a new TB (genuine VW) and lambda (BOSCH - not the universal one, I checked which one is for the AHW engine), erased the fault codes, calibrated the new throttle body, but the shaking from the front was still present. I went to a tyre shop, all 4 wheels were balanced again and in meanwhile 4 new NGK spark plugs were installed, but no difference whatsoever.
The car is still shaking.

The symptoms are:

The shaking (without any noise) is starting to feel somewhere between 50-60 kmh (31-37 mph), but, BUT only when I'm pressing or holding the throttle pedal (accelerating or at constant speed). As soon as I remove my foot from the throttle pedal, the shaking disappears. Above 70 kmh (44 mph) the shaking starts to intensify. It does not disappear at any speed above the 50-60 kmh when I'm holding the throttle pedal.

The important thing is that the shaking is present only when the car is accelerating or at constant speed, but not when I remove my foot from the throttle pedal or just start to brake with the engine. So according to this it can't bee the wheels...

The complete front running gear/suspension and brakes were changed/renewed in meanwhile... without any influence to shaking... The injectors were cleaned with ultrasound treatment by a specialist and checked if there is a faulty one. Furthermore the whole intake manifold was removed, cleaned, checked and refitted with a new MAP (Continental) sensor... but still no change...

Does anyone had a similar problem?

I have few ideas (engine mount, clutch etc.) But this is a 15 year old car, I don't want to spend a small fortune for changing random parts...

So any advice is welcome (except to sell a car, that I can't for ~1-2 more years :) ).
 
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