Hi all

I origionally had a jerk down low at 0.6 bar and above so i changed the y pipe under the intercooler and that went away now it jerks anything above standard boost ie 0.8 bar ... really confused cos i know its not the fuel cut ... could it be that another pipe is leaking .... ??

any thoughts welcome ...
leeps
my98 uk impreza turbo sedan

Jerkyness can be faulty sensors. Namely air flow, o2 or the idle control. If you got a friend with a similar model who is happy to play swapsies that would be the easiest way to sort it.

Could be lack of fuel.. do you have an AFR monitor?

Or a spark problem..

I have a single judder at 5k rpm when running more than 1bar which I think is spark plugs or coil packs.. need to find the time to investigate..

Also you will get judder if fuel pump or pressure is low.. fuel not getting in to cylinder quick enough..
Which like said could be lambda or more likely MAF sensor, or if the car is modified it could be running lean.

You need to check the AFR when it judders ASAP.

Also when was the fuel filter last replaced?

JGM :)

You say you have a jerk? Is it the violent type such as the fuel cut jerk?

Are you getting the boost reading from one of your guages?

It may be the case that one of the hoses has a split in it, and overboosting, but as there is a leak, only showing .8 bar on your guage.

Are you down on power, or does the turbo seem to spool up pretty quickly (a sure sign of a leaking pipe)?

I would be very careful if it is overboosting, as you could possibly cause it to detonate :(

But then again, it could be nothing to do with this at all ;)

If this is any help?
My 93 WRX is has the simalar problem
Had it in for a service/Cam belt change etc last weekend(big bucks)
3 of the coil packs were goosed
plus ecu diagnostics showing that the O2 sensor is dodgy

Best to change all four at once.. btw..

JGM :)