Intermittant Loss of Power

[Steve Killoran]

Strange thing happened on two occasions (different days) recently, approaching a junction changed down and about to pull away and the engine just seemed to loose power! It is very much like the power loss you get when you press the brake pedal while driving, this is something I often do when I've cleaned the car and take it out to fully dry off the discs.

My car is fitted with PSM.

Any ideas as to where to look first. The car has covered just over 21K miles.

Thanks

 

[Richard_Hamilton]

I note that you emphasise that your car has PSM. Was the PSM light flashing?

My first reaction was that it sounds like it might be a MAF sensor problem (a PSM light might confirm that), but it is unusual on a car with that mileage. Unless you have an oiled air filter of course - they often muck up the MAF. Best bet would be to get a diagnostic check done, and see if there are any faults recorded. If you are anywhere near me I'd be happy to help with that.

 

[adrian996]

Hi Steve. I would think that it sounds like a fuel/air problem too. However, just a long shot, but someone told me not so long ago that you need to get the PSM re-set (by OPC or preferably someone with the relevant kit) following having your wheel geometry done. Just wondering if you've had your geometry tinkered with in the past and not had the PSM re-set. (The re-set involves simply plugging in a laptop to the scart like plug just under your dash on the passenger side. It's half an hours labour.)
The only reason that I mention this is that your symptoms (as though you're braking and trying to power-on at the same time) sound like it could be the PSM playing up. Apparently, if not set up correctly after a wheel geometry set up, in certain situations, the PSM can mistakenly think that you are in trouble handling-wise and try to correct it by applying one or more of the brakes to try and sort things out.
I'm certain that there are people who'll read this and think that I've wasted £50 on OPC labour but it did make me wonder what the outcome might be if something like this were to happen at any significant speed - ie. at 70mph in a straight line with someone right behind me(?).
You're independent or any OPC can easily diagnose a fuel/air problem - I would think - should the need arise.
All the best.
Adrian.

 

[Steve Killoran]

Richard/Adrian

Thanks for your responses, I tend agree I also think its related to the PSM. Strangely I have always had the same response from the car when I brake while applying power at the same time. I have not had anything done with the geometry, but I have replaced the rear tyres recently!

Richard,

I am in Reading and I am hoping to go to Club meet this weekend, you going?

 

[Black80XSA]

Applying the brake and accelerator at the same time results in the response you describe - it lasts a few seconds after releasing the brake pedal - my old 986 did it, and the 987 does it too. I assumed it was due to the ECU getting confused over throttle position and the brakes being on. I use the procedure you descfribe for drying the brakes after washing for a distance of about 50 yards.

 

[Richard_Hamilton]

ORIGINAL: Steve Killoran
Richard,

I am in Reading and I am hoping to go to Club meet this weekend, you going?

Sorry Steve - I'm going to Silverstone on Saturday to help a friend of mine with his GT3 Cup car, and two day passes in one weekend from 'er indoors might be pushing my luck.