My 2003 Blobeye Impreza WRX went in for a re-map as the fuel cut was kicking in causing it to loose power (or so I believed). It turned out that apparently the MAF sensor had gone which was responsible for the running problems I'd been having, this was changed and the car was mapped.

It ran brilliantly for about a month and then out of no where the same problem came back. It feels like the power has gone from the turbo it just doesn't pull as much and feels like it's holding back. My first thought was that the MAF sensor had failed again. I had it tested and have been assured that it's working perfectly and within the parameters.
The weather seems to affect it in some way as it occasionally goes back to normal again when the air is cold.

Do any of you have any ideas what could be causing this loss of power in the turbo?

Any help/advice is greatly appreciated.

 

anyone?

 

If you are sure the MAF is fine, then contact the person who did the mapping for advice. Has anything changed since the mapping, different fuel or filling station for example. Yearly I take mine to the guy who maps it for a rolling road session just to check things out, on one visit I was down 40bhp. Two weeks later I was back upto the 360bhp. At the time of the RR session we said it could be fuel as I had filled up about 150 miles prior to arriving. This was proved as I had not done anything apart from refuel, prior to the RR shoot out when it was back to 360 bhp.

 

Thanks for your reply 360ste. I've been using exactly the same fuel Tesco 99 ron (from the same petrol station) which is what it was mapped to, so it can't be that.