Boost spikes.. sometimes ? Greddy profec boost controler EVO

Hi

I have a Greddy profec (blue with the large display and dial) Installed on my lancer evo 5.. stock engine larger exhaust, filter, pump, FPR...

Problem is that my boost controler sometimes overshoots its targets.. even within minutes.. Some pulls it goes as planed.. up to around 1.45bars and holds it to what ever rpm i rev. to.. then it might spike.. other times it goes to around 1.45 first and tampers off to 1.2 same gear same road same time.. same drive..

Im not seeing any knock.. thought that it might pull timing or something.. AFR seems fine to.. But it is running with the lean spool engaged still.. maybe that has something to do with it..

My problem is that its not the same.. so i would think even that the wastegate is around 0.8bar stock it would sometimes be fine at 1.45..

Any hints to what to check.. (still using MAF so i can see on the AFR if any bigger leaks in boost pipes btw)

It's hard to say what might be going on there with a standalone boost controller as you can't directly see what the controller is doing to the wastegate duty cycle. It may be that there is a mechanical issue or it may be that there is an issue with the controller itself. I have used the Profec boost controllers several times and actually stopped using them because I had two that occasionally just gave all of the boost for no apparent reason. not an ideal failure mode!

Funny you should say that.. my friend just bought one also.. and at 53% duty the boost was fine around 1.35bars.. and was ok stable.. but at 54% we got like spikes and stuff.. :-(

Would you recomend going 3 port.. ecu controlled insted?

I always try and get the ECU to control as many functions as I can. I'd use a MAC 3 port solenoid.