4.6 gone sluggish

4.6 R/R P38 2001 - 117k miles

Drove to London from Devon last Saturday, nice steady 70-80 drive all the way, nothing untoward. Came off M3 (first time I really had to reduce speed) , pulled away from roundabout and noticeable lack of power/response. Also appears to have developed a 'turbo' style whistle on acceleration. Returned Sunday - again no problems when up to speed, just sluggish getting there & uneventfull journey home. (still with whistle which disappears at cruise speed)

Observations:
Temp constant - no overheating
Fuel consumption - no perceptible change (monitored closely on return journey)
Lumpy tickover
Noticeable whistle (noticeable on acceleration only)

Got the feel of firing on 6 but compression fine, each plug lead removed in turn on tickover and noticeably down on 1 cylinder in each case, so all appear to be firing.

Revving engine in neutral doesn't like going past 4K - almost as if there's a rev limiter kicking in. No noticeable misfire, just doesn't want to rev.

It was fine when leaving for London but something has gone amiss on the way. Mate at local garage a bit stumped, says he's had a few p38's with knacked cams and has known cam lobes to wear dramatically if case hardening wears away, but I don't want to start ripping her apart without exploring potentially simple probs. Looked for possible causes of whistle like air getting in somewhere but nothing obvious found.

Any ideas anybody?

You would soon hear if it was the cam so it ain't that
Is the air cleaner needing changed ? - whip it out and go for a blast to see if there is any difference
Possibly fuel related (ie lack of ) - check/ change the fuel filter
Look for fuel leaks where the pipes come out of the tank in case it's drawing air there or anywhere else
Sounds to me like it could be drawing air from somewhere - check all the hoses/connections associated with the induction side of things
Does the engine struggle more under load or just generally down on power ?

MAF sensor

Tervueren said:

MAF sensor

Click to expand...

Mine came out (diesel) and it was sluggish, lucky i found it was hanging out, i put it back and all was fine

Thanks for the replies

Strangely, things have gone from bad to worse. Took the MAF out this afternoon and gave it a blast with carb cleaner, replaced and no change.
Knocked off at 7 & set off home (about 5 miles) and just about made it!
wouldn't go past 2000 rpm and felt like it was firing on about 3 or 4 - absolutely gutless - if I tried to give it any more it just about died so had to gently coax it home.

I'll get a new MAF in any case but will let all know how it progresses. Time to get the old softdash off of SORN methinks.

Don't buy a cheapie they're crap

Tervueren said:

MAF sensor

Click to expand...

WHAT IS : MAF SENSOR ? AND WHERE IS IT FITTED IN THE CAR ?

STOP SHOUTING!


and look here - where yu also asked.

Quick update for those that are interested.

Was away for a couple of weeks on business and got back and decided to give the 'ol girl a good seeing to (the car that is - not the missus!)

Further tests indicated air pulses coming BACK out of the air flow sensor - she just wasn't breathing properly and still wouldn't rev past 2.5k - misfiring & spluttering.

Engine area hot - very hot! tailpipes lukewarm.

Loosened cats off header pipes & bingo! - knacked (nearly blocked) cat on nearside. "Turbo whistle" I can only assume was exhaust gases trying to squeeze through available space in cat. Sounds like a bloody Nascar racer now. Only wish I could leave it like that!

Thanks for everybody's input. All's well that ends well