I have an 01 wrx. After changing burned pistons with forged ones, and assembling all together again I start up the car and everything looks ok, but then I rev it up to 4000rpms and after aprox 2min the rpms drop to idle. To rev it up again I have to take my foot off accelerator and hit it again. This only happens when I rev over 3700/3800 rpms. I think this must be something wrong with my turbo or boost solenoid. Can anyone help me?

Thanks

 

why would you want to hold it at 4000rpm for 2mins?

I presume the ecu is trying to sort the idle and as you are at light throttle input you are within idle critiria so the ecu pulls the rpm down..

does it drive okay at all other times and any check engine light?

Simon

 

Hi. I was holding it at 4000 rpm because I was refilling the coolant, so I have to heat the engine so the cooling liquid circulate and then leave it to cold down, refill coolant... and so on so on... until reach the correct level, as stated in a document I read.
I have not drived the car yet, because I have to take it to the "MOT" here in Portugal.
No check engine light, no fault codes.


Thanks

 

you can so that at normal idle.

I suspect it is purely the ecu trying to sort the idle..

Simon

 

Long shot here but you might want to look for an air leak. Its a cheap start to eliminate things.

 

already checked for air leaks....