Hi,

Got a MY99 Turbo 2000. Generally runs fine, just been fully serviced including spark plugs, air/oil/fuel filters + engine and diff oil. I know it needs the hose from the block back to the recirc valve changing (some idiots replaced it with a hose of a Dyson or something, and it's a bit loose seeing the jubilee clips knackered also).

But - when accelerating gently, from around 2000-4000revs it's like its got a limp or its asthmatic, goes fine past 4000revs though? Took it to Subaru and they gave it a quick test drive and were vauge as you'd expect. All the mechanic did say was it was 'tailing off' and that if left could 'melt the piston' and therefore I should book it in - surprise surprise!

Suspecting a sticky solenoid or wastgate actuator or something like that? Anyone else got any clues?

Cheers
M

 

I'd sort the vacuum hose to the dump valve first, if it is leaking then on boost some of the air will be pissing out of this rather than going into the cylinders. As this is metered air (i.e. after it has gone through the MAF sensor) then the ECU will be injecting the corresponding amount of fuel and will therefore be over fuelling. This could well make it sluggish.

If you sort that and it is still not right then my money is either on the Lambda or MAF sensor. Lambda would be more likely as when the ECU goes open loop (e.g. 3-4k revs upwards and positive boost pressure) then the Lambda reading are pretty much ignored by the ECU hence it runs okay when pressing on.

 

Oh and I would get it sorted ASAP as failing MAF sensors are well known for causing engine meltdown

 

Thanks for that info, CD. It sounds exactly what I am experiencing AFTER I changed to a known good MAF. A bit hesitant (AFR dropping to 17:1 momentarily) below 2.5k and revs dropping to 500rpm when I dip the clutch.

Sorry for hijacking.

 

Nice one CD! I was wondering what the impact of that hose being a bit loose could be, and by the sounds of it that could well be playing a part, despite the jubilee clip I managed to just pull it straight off without any force. Got a new replacement coming in the post already so should have it in a day or two - once changed I'll see if there's any difference...freaking hope so coz my MPG is shocking! Failing that I'm going to clean the solenoid and wastegate actuator and change the MAF also.

 

Myles, did you reset the ECU after changing the MAF? The ECU will have stored various trims for fuel based on the MAF and lambda readings it had before, and the trims will no doubt be different when changing the MAF. It will re-learn these but a reset may be quicker.

JediJester it is quite possibly the Lambda sensor, I sometimes get the pulsing lack of power at 2000-3000rpm that you describe and mine has once thrown the CEL for lambda. I checked my lambda readings and the maximum it is ever reading is 0.69v which is too low, so could do with a new one really. BTW MY99 (AE800) cars are a little prone to this anyway when the engine has only been running for a few minutes. From some peoples opinions the AE801 ECU is a little smoother.

 

Question actually on this Lambda sensor. On Ebay and there seems to be 3-wire and 4-wire, both for Impreza Turbos - is there any real difference?

 

Yeah, I did the reset straight after the new MAF. That is why I am interested in how the front lambda sensor works, sounds like that may be my problem.