Wrx reaches 4k rpm then starts stuttering and won't climb

[larrysteve]

Hello, I recently bought a 1997 legacy rs that had a single turbo sti motor swapped in and it doesn't go past 4k rpm it's almost like hitting a wall and it won't climb in rpm. Until that rpm it boosts to around 5 or 6 psi and feels normal. Even when going down a steep hill it will not climb but still stutters away as if it's starving of fuel or lack of spark, done spark plugs, coil and apart from fuel pump I don't know what else It could be? Maf? I've tested for boost leaks but seems to be completely fine, idles a little funny but not horrible, won't hesitate when revving out of gear but as soon as there's a load on the engine it won't climb rpm. Any ideas?

Set the title to wrx only because it's a wrx sti motor and that's what I'm having trouble with. It's a v4 motor for those wondering 

Can post video of problem

Cheers 

[savage bulldogs]

Did it run ok for long after the conversion ?

Have you checked the ECU for codes and done a ECU reset ?

Could try cleaning the maf with brake cleaner before buying any parts .

When you changed the spark plugs did they all look the same colour , if one plug was wet with fuel or a different colour to the rest ?

it might indicate a misfire on that cylinder , as the symptoms sort of sound like that might be the issue 

 

[larrysteve]

On 3/29/2020 at 2:06 AM, savage bulldogs said:

Did it run ok for long after the conversion ?

Have you checked the ECU for codes and done a ECU reset ?

Could try cleaning the maf with brake cleaner before buying any parts .

When you changed the spark plugs did they all look the same colour , if one plug was wet with fuel or a different colour to the rest ?

it might indicate a misfire on that cylinder , as the symptoms sort of sound like that might be the issue 

 

Ran mint for a week, cruising at 100, stopped at a stop sign, and when I took off it started doing this. Gonna try the codes soon and plugs all looked alright