Petrol-Head

Hi all...

Our Scooby MY99 has been playing up lately, my wife was driving it on the motorway and it lost power the more you put your foot down the more it sort of spluttered and then dies. We pulled over and it would start.

Popped into Power Engineering (very helpful) and they ran diag's on it and replaced a faulty cam shaft position sensor, all was then ok with the car. I also replaced the MAF sensor as it was hesitating when accelerating. Car runs sweet now.

It's still losing power sometimes just like last time..any ideas same fault.....???

Thanks for any help.....

Splitpin

Not really much to go on there. It's statistically unlikely to be a recurrence of the same fault(s) as you presumably have two new sensors in there.

Has the Check Engine light been coming on when the power goes? If so, use the black plugs under the dash to run your own quick diagnostic and tell us what, if any, fault codes are stored.

Re. the MAF sensor, do you have the standard induction tract, airbox and panel filter fitted, or something else?

LizP

Have you thought about the Lamda sensor in the exhaust system? Mine went last year following the same sort of symptoms (although the engine light also came on). Hope its not though, as it costs a few hundred quid to replace. It should have been platinum plated at that price.

Splitpin

Depends where and how the car is "losing power". Closed loop fuel control is switched off when the car is being driven hard so if the OP's power loss is happening under hard acceleration, a failing O2 sensor is unlikely to be the cause. If the loss happens under cruise/low throttle though, then yes it could be a factor. As above the black plugs may tell a story.

Ahem, oxygen sensor elements are actually platinum-plated. However, you should not pay "a few hundred" to have one replaced even at a main dealer. Subaru's price for a new three wire sensor is currently £140-odd, and it's a five minute job to change. Even allowing for a bit of diagnostic time there shouldn't be more than an hour's labour in the job.