Losing power intermittently

watfordkev · Jun 15, 2013

My P38 4.6 Vogue, 2000 on a W plate, 106k...

On an incline

intermittently loses power - significantly -
picks up power again 'when it feels like it' so to speak - nb does not over-rev but gradually picks up power again
will not rev above around 3000rpm in these moments

Additionally

The above issues only tends to happen going uphill
The car never feels like it will stall
There are no leaks
The car starts, idles (and stops) very smoothly - no unwanted noise etc

I am going to submit it for physical examination with a specialist but I wondered if anyone here might have any advice / ideas? Thanks!

StuckAgainSteve · Jun 15, 2013

Sounds like a knackered MAF or a poor connection to it.

Stufer · Jun 15, 2013

Yep or possibly coil packs, mine caused similar hesitation under load.

Datatek · Jun 15, 2013

In tank pump?

TSC · Jun 16, 2013

My 2000 4.6 did the same, it was leads and coil pack, changing these improved it a lot however it still did not rev as it should, changed MAF sensor and all was well.

StuckAgainSteve · Jun 16, 2013

Also ensure the car hasn't been fitted with some sort of oil impregnated "sports" air filter like a K&N, the oil from it will kill the MAF. If you have access to any old cheapo OBDII reader that does live data - check the airflow values from the MAF at the revs specified in RAVE. You will also be able to see if the cats are lighting up causing the Lambda sensors to flip between high and low voltage. The other two Lambdas will show a constant voltage (.447V?) to keep the EMS happy as they aren't actually fitted! (AFAIK four Lambdas are only fitted to North American Spec cars.)

Losing power intermittently

watfordkev

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StuckAgainSteve

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Stufer

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Datatek

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TSC

New Member

StuckAgainSteve

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