Violent loss of power

[red_baron 0]

Hi All,

 

I have a confusing one... the car's not really been used since November (its had the odd trip out, but nothing longer than 5 miles at a time). I've been having some bodywork done for the past few weeks - picked the car up on Friday & ran it to and from work with no problems (about a 30 mile round trip), in fact it seemed to be running better than ever. It was fine on a short trip on Saturday too - did an oil change up on ramps (not sure if it is the root cause of the problem) and ever since then even under moderate acceleration, the engine dies quite violently momentarily and then runs ok. I have to drive the car with virtually no throttle when accelerating, otherwise the power disappears and the car lurches forward.

 

It doesn't stall, no lights come on the dash & it only lasts a fraction of a second. I've run VAG-COM and there are no fault codes logged. The car starts & runs fine otherwise & I can boot the throttle no problem with the car stationary & out of gear (i.e. no engine load).

 

The car's a 1993 VR6 with about 125k on the clock.

 

Any ideas more than welcome!

 

Cheers,

Ian

[fla 9]

change the ecu relay no 109.

[red_baron 0]

ECU relay replaced but the problem's still there.

 

Seems to have appeared only after oil change - haven't a clue where to start. The loss of power seems more mechanical than electrical, I'm hoping I've not done something to the clutch with putting it on ramps (it's been on ramps quite a few times lately).

 

Any more suggestions?

[fla 9]

apart from that the other potential issue could be the crank sensor, but this is pricey. About £90 from the dealer :shock: Otherwise electrics might need to be checked, coilpack, leads, earths etc.

[muppetlab 0]

Had a similar problem with my vr. Would buck under acceleration but not constantly and could never pin point an exact senario. Replaced loads (plugs, leads, maf, sensors etc. by chance replaced the throyyle postion sensor on the throttle body and reset the ecu. Problem solved. Not sure if thats your problem but may be worth checking and a cheap second hand fix.

[fla 9]

something I picked up today - my car just cut out in third gear. Happened twice. It was ok in 1st and second but as soon as i changed up to 3rd it would die. The problem - the positive to the starter solenoid was shorting on the gear selector channel. So i loosened the lead and moved it around away from the selector tower towards teh front of teh car. problem solved. It may be your issue, it may not be. But there may be something like that causing your loss of power, if all else is checking out ok.

[red_baron 0]

Well... this may or may not be a fix. My Dad (much more patience than me, and also retired so lots of spare time) took a look at the car today. After changing the ECU relay there was no difference. Today he took the ABS fuse out and ran the car - same violent loss of power under acceleration. Put the same fuse back in and it appears as though the problem's gone away. He did about 10 miles with a couple of bursts of "proper" acceleration (he's nearly 78 so I bet he surprised a few people) and there were no issues. I've just driven it home and there was no evidence of it either, although I didn't give it the full beans as I didn't want to tempt fate.

 

The sudden loss of power seemed more mechanical and I suppose looking into the braking system was a logical step. Seems weird but if it's fixed then so what! Fingers crossed its not just a temporary fix...