Power loss at high revs

[cleopatra]

Recently I've noticed that as I accelerate past 5000 rmp the engine stutters and struggles a little. This is a new problem to me as only last week i was marvelling at the power between 5000 and 7000 rmp.

What I want to know is what could be causing this? I rarley drive it this hard but like the occasional thrash!

It seems to me to be either spark or fuel but these are just guesses.

Could it be old spark plugs? What should I replace with?

I'm not sure if/when the cam belt was changed (getting it done asap) could this affect the high revs?

Thanks in advance.

[Subaru ETA]

bad plugs or rocker cover gasket has leaked oil into the spark plug holes?

[mpau009]

It sounds very similar to Kenneths miss fire problem, which was caused by tired sparkplugs, it was fine lower in the range, but at 10psi plus, it started to miss. If you do a search, i think theres a dyno graph around. It wasnt violent at all, just enough to knock the top off the power curve.

[bradc]

plugs are the first things to check

[cleopatra]

Thanks all.

What plugs should I replace with? Car is standard.

[Subaru ETA]

do a search on spark plugs

[cleopatra]

Gonna get the NGK irridium ones.

[MPBVr4]

Don, "ancient of mu" had a similar problem which was eventually put down to the fuel pump. It seems there are different levels of voltage applied to the pump, one at lower revs & one at higher revs. The higher level of 12 vdc wasn't being sent to pump hence no power at high revs. :inquisiti

[ritch_w]

I'd bet you your mortgage the filter on the fuel pump is clogged up with crap and looks like a Tea bag!

I had the exact same issue last year with the leggie when gunning it above 5K rpm. Uprated fuel pump from wodjno fixed. cleaning or replacing the filter on the standard fuel pump will probably help too.