car is struggling to start when hot have to try 3 times and use accelerator pedal as well, also idling low when pulling up to traffic lights, then sorts itself out and holds at 900 rpm but drops to 300 initially, has cut out once as well same thing when slowing down not on gas, also very jerky when going onto gas with light throttle and when lifting off it jolts a bit, if revs are higher than 3k it's o.k when you lift off and go back on again but when revs are low it jolts and shudders before picking up, apart from that when on boost it's going really well!!

Sorry for rubbish description but not really sure how to describe it!

Other than very jerky when on and off the gas at low revs!

Any help greatly appreciated

 

what year?

is 99/00 then probably maf.. if older then perhaps an intercooler or vaccum leak

 

Hi Simon,

It's a 1995 JDM WRX

 

probably coil packs..

 

They are new !
As are the plugs, only does runs crap when hot, when cold all is tickety boo!

 

You were right 1st time it was a vacuum leak, pipe under the intercooler has a tiny split in it!

 

time for an upgrade

 

Good idea, it's not silicone like the rest of them!

 

temp fix if you have the right size silicone to go over it though

 

just a thought mate, check your earthing

if you have a bad earth, the car will struggle to start when hot
scoobs are badly earthed cars really

 

The brightness of the lights goes up and down when sat on idle (noticed this tonight)

Also it's now hesitating off boost at 2k revs (like it doesnt want to go, kind of holding back) when it's on boost it's flying though!

 

have you had the alternater & battery checked at all

i always check the simplest things first, then work to the tec side

 

I thought the problem was solved?

 

It's was until I wound the boost back up to 1.4 bar, in hindsight I probably should have left it on 1 bar until getting a new hose

Im going to replace all the boost hoses this weekend with shiny new samco ones, going to get some silicone vacuum pipe as well, sort it out once and for all!!

I have same symptoms as before, lumpy running under 3k, jerky throttle response, judder when lifting off the throttle and a pig to drive slowly!
Im putting it down to a vacuum leak somewhere!