New impreza running problems

[jmj]

Hi all, new member from Kent with my first Impreza UK 2000 with 104k miles. Unfortunately it's not running quite right. Apologies for the long post but trying to give as much info as possible.

It ran fine at first but in the last week or two it's throwing a CEL on the motorway under load in 4/5th gear. It also went through a stage of low boost around 6psi and on one occasion the boost  dropped so quick it threw me forward quite hard, but it's only ever done that once.Tthe car idles fine and doesn't misfire, the CEL codes were 23 MAF and 32 Lambda. I cleaned the MAF and the code hasn't come back but the Lambda code has. Since the MAF clean it boosts up but will either quiver between 12-14psi, or it will gradually drop to about 8psi. 

I've cleaned the boost solenoid, MAF and have a new set of NGKs ready to go in. I haven't changed the Lambda as I'm reluctant to spend the money on a new one if it's throwing the code because of the decat. Has anyone had a similar problem? Could it still be the old MAF knackered?

According to the last owner it's running around 270bhp with the following engine mods:

Remap
Decat
Yellow injectors
Aftermarket induction kit
Boost gauge
Dumpvalve
Samco hoses
Shortshift
FMIC (fitted but not plumbed in yet)

 

Thanks

[Swino]

Do you have proof of the map?


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[savage bulldogs]

What year uk 2000 is it ?

Could be a boost leak but proof of the remap would be good , as if mods haven't been "mapped in" it can cause major running issues .

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[jmj]

No, theres no proof. I got the car at a decent price but with barely any paperwork. Is there an easy way to tell? 

[savage bulldogs]

It depends on what version it is , version 5 (98 0nwards ish) can have the standard ecu remapped with ecutek software . So the ecu will look stock inside .

Pre late 98 have to have a daughter board soldered in or replacement aftermarket ecu to allow them to be re mapped

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[jmj]

It's a year 2000 so guessing there's no easy way to tell. 

I've booked it in at a specialist now so I will see what they come up with.

[jmj]

Just an update for anyone with similar issues - had a smoke test done and the dump valve was leaking. Had FMIC plumbed in and a new DV, it now holds boost and runs much better.

Still getting the odd code for Lambda sensor but assuming this is the decat.