uk 2000 with a flat spot, please help!
 

hi all, i've just bought a w reg turbo 2000 an when it gets to around 4500-5000rpm theres a flatspot an then it clears. its like its restricted for second or so then o.k. does this in every gear.
its standard apart from downpipe back stainless exhaust an bailey dumpvalve.
any help would be appreciated, cheers.

Welcome :D well we will start with the dv, could be the cause of the problem, or it could be the (full decat?) exhaust causing overboost, or it could be the boost solenoid.

Tony:)

cheers, it only has the center decat, it certainly isn't overboosting(feels slow tbh, especially after the pulsar i've just sold) it just dies off abit then comes back. can i just bypass the boost solenoid so it just runs actuator pressure to rule the solenoid out?

On an 00 car it could also be the MAF sensor. Is the idle stable ? If it isn't then get a new MAF (£80 or so) ASAP and keep off boost until you do. An ECU reset will often highlight this... Scoobypedia | Trusted knowledge for everything Subaru | Knowledge / Reading ECU Fault Codes

idle is spot on mate. i'll look into reading faults, thanks.

has no one else suffered from the same problem?
don't wanna take it to main dealers an have my pants pulled down.

Lambda sensor.

Unplug it and take it a drive, see if that cures it.

cheers mate, i'll give that a try.

If it feels like the ignition has been switched off and then on, and is really violent, then its classic overboost fuel cut, someone has upped the boost and its going over the fuel cut and triggering it, its a complex strategy (fuel cut doesn't hit as soon as you go over) and classicly it triggers at 4000-4500rpm.

Run actuator boost and see if this confirms it (Bet you a tenner at evens it will!)

Simon

its definately not overboosting mate, had this with other cars. its not violent at all. just seems to back off slightly then come back.
tried oxygen sensor an made no difference.
run actuator pressure an seems slightly better but still not 100%.

Have you resoved this yet? I have the same prob, have disconnected the Lambda sensor but no joy. Anyone know where I can take it in Hertfordshire to get it sorted? Thanks.