BlackLazarus

hey guys, car lost boost completely. It is now practically NA. I've taken out aftermarket boost controller and put in the stock only to come up with the same result - no boost. Looks like a wastegate actuator issue or something related to it, like air leak that's gone worse.

stand by vac leak then..
cracked pipe, loose connection, doesnt give you grief up high revs but down low all jumpy n rough.
or wastegate issues? but i think vac leaks

what was the catalyst? when did it start.. did you do a engine bay clean or anything?

started after i treated it with upper engine cleaner (as per canister direction). few revs to purge the remaining chemicals out, and there it went..CEL + rough idling.
i'll have another look. hopefully i'd find something.

02 sensor only causes problems when the car goes into closed loop mode while cruising AFAIK

so like when on the freeway at 100 for a minute.
the whole lot is bypassed when on cold start.

Hell i even ran my car without an 02 sensor for a while.. just disconnected it
it just makes the car run rich

i would be checking for vac leaks
and resetting ECU

What car btw?
any codes? i.e. the flashing ECU codes..
search connecting the dash plugs and read the flashes..

Car is '02 B4 manual. Code is as per subject P0171/P0172. I've used ECUexplorer + tactrix 1.3. I've reset the ECU multiple times, and after a few minutes, I'm back to #1
Thank you.

spraying the o2 sensor with throttle body cleaner has probably made it worse. they can't be cleaned.

there was an article in the US that says so. maybe that was wrong...maybe i shouldn't of!
it's a $189 replacement from Bursons; a leg from Subaru.
thanks heaps.

is there a way to test (using mulitimetre) O2 sensor? it doesn't show in the service manual.

thanks for the replies.

Yes i have reset the ECU. the CEL goes away then comes back just after 15mins in idle.

Cleaned up oxy sensor with throttle body cleaner. Is this bad? It didn't have gunk and that whent I took it off.

Sprayed upper engine cleaner in the manifold: temporarily disconnected one of the three vacuum hoses on top, centre,front of manifold. That's where I usually spray it all these years, always with good result but now.