15 replies to this topic

[BlackLazarus]

Hi all, as per subject, need help with the above issue.

1. Check engine light comes up as the engine starts misfiring, surging, hesitating, stalling, struggle on hill climb, sounded like old VW beetle, white and or black smoke.

2. Runs fine when cruising at 70-130 kph, comes back to #1 below 70 kph, specially in slow traffic, worse in the basement parking.

3. DTC output was P0172 (system too rich) on the first day, then P0171 the next (system too lean).

4. Thoroughly cleaned up MAF sensor, O2 sensor, checked vacuum/intake lines in good condition, no exhaust leak, there is fuel in fuel return line from fuel pressure regulator

5. Pretty much done everything google and yahoo has to offer, except inspecting injectors and fuel pump.



Only things I've done prior to #1
a. added subaru SA718 fuel additive to full tank of BP ultimate.
b. treated with upper engine cleaner, revved as directed......then the nightmare began.

If you came across this same issue before and resolved it, could you please share your thoughts, I need some direction please. Thank you.

[Shaz]

Have you reset the ECU?

I know, it's obvious, but it's normally the most obvious things.

Cheers,
Shazza

[alexGT]

how did you "clean up" the oxy sensor. AFAIK once they are gone they are gone!

[aekOne]

where did you spray the uec?

[BlackLazarus]

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.

[alexGT]

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.

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

[CodeBurn3r]

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..

[BlackLazarus]

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.

[BlackLazarus]

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.

[CodeBurn3r]

Car is '02 B4 manual.
Thank you.

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?

[BlackLazarus]

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.

[implanted4]

guys the whole point of the oxygen sensor is to monitor the O2 levels in the exhaust gas. if the sensor has gone bad, then its likely the culprit. Just unplug it, the ecu will just run from base maps, wont run richer, just wont have closed loop capability until its replaced.. if the sensor is intermittantly causing the issue, better off disconnecting it anyway.

[Eddie]

Have you checked fuel pressure/fuel flow/air leaks etc as this is a common thing to bring up these codes.
Cheers

[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.

[Shaz]

Intercooler piping split, or popped off mate?

[12.SLOW]

try changing the knock sensor dnt know if it will help but its a cheap repair