Car feels very Flat
 

Hi,

I have a 99 Forester Turbo S. I had an engine check light, seemed it was the Knock sensor. Replaced this and everything seemed fine for about 6 weeks. Just been on a long journey and the car feels very flat. Normally at about 75-80 on the motorway it is just coming on boost (Its a 4 speed auto) and usually feels very responsive. Now pretty much nothng happens when i put my foot down, it is certainly not on boost, then it shifts down, comes on boost and goes. It also seems to come on boost later than usual but when it does it sems to go fine. Driving up and down the Nork Yorkshire hills the car felt very sluggish. I originally thought maybe a split pipe but cant spot anything. I also thought maybe the seals on the turbo but there is no smoke. Any ideas on things to check will be much appreciated.
Many thanks

Dan

Have you tried resetting the ECU,
What fuel are you using?

I was about to say what fuel lol

Mix of Supermarket ****e & Shell. Probably more supermarket. Will stick a full tank of Shell in and see if this makes any difference

Thanks

And reset your ECU, if you have used crap fuel your timing wont be optimal,
Reset and have a 5 mins steady run, then see, it gives time for the IAM to find the sweet spot again.

a little delayed response. New baby arrived. Tried the above and still not right. Could it be a bad knock sensor? No engine check light on. Any other checks I can do ? Thanks

Changed your spark plugs recently?

Might be worth a post asking any local owners if they can try and read your ecu errors, as its a 1999 Im not 100% if you are OBD or the old SSM(IIRC) compliant,
They ECU may not be allowing full power anyway due to the EML being on.

It's OBD, I have both 1998 and 2000 model and both the same.

Blocked/broken up cat maybe?

No boost at all is always most likely to be a leaking/badly-sealed hose. I would look at the intake to turbo elbow first.