I have a standard 1993 WRX which has developed a flat spot at 4500-5000rpm.
If you gently ease off the gas and then give it full pedal again, away she goes.

It tends to do it after about 30 mins driving and the max boost then is 0.6 bar, however if I drive for 20 mins or so off boost, i get 0.8 bar and the flat spot isnt noticeable.

So far Ive had new plugs (PFR6B) and a new coil pack, No 3 was cracked.

Has anyone had experience of this?? could it be electrical even though there are no fault codes??
What about boost control, blocked hoses even though its internmittent possible heat related.

Suggestions much appreciated...
Im at abit of a loss!!

Cheers Richie

 

Richie,

Check the condition of all your turbo hoses.If they don't have hose clips,zip tie them.I'm not certain if the '93 has a dump valve.If it does,take it off and see if you can blow through it.You shouldn't be able to.Try pushing the piston,and see if it moves freely.You can clean it with carb' cleaner.Make sure it's dry,and then give it a light spray of wd40.Clean/dry off any excess.

It's possible that the solenoid is playing up.Or the waste gate/actuator could be sticking open.

Sorry,but it's very hard trying to pin point a problem.These are the mechanical things I can think of.

Hope this helps,

Mark.