Ive had this problem pretty much since I finished swapping a 94wrx EJ20G into my 1993 L and I thought it might be some IC leak or cracked hose somewhere so I finally started poking around and I cant find any leaks or cracks. So far I swapped the TMIC for a better IC with silicone tubing instead of the crap plastic piping that comes stock and that had no effect. Checked hoses and couldn't find anything.

The problem starts happening somewhere around 8-9psi under wot. If I have maybe 3/4 throttle it doesn't seem to be an issue. I have a walbro pump so it should be starving for fuel. Any ideas?

 

Is it a complete loss of power or just limiting?

 

limiting when the studdering occurs... the rpm keep climbing but studdering is occurring the whole time

 

bump !!!

im also eager to see whats going on here as mine is doing EXACTLY the same , when i hold the throttle 3/4 theres no problem but if i floor it , it really really seems to boost funnily , my boost guage goes wild flickering around , i only bought my car yesterday its confusing me !!

 

Im going to try new plugs, checking coils and new fuel filter sometime next weekend. Ill keep you posted.

 

nice one buddy !!

 

Have you checked all the boost and vacuum hoses from the inlet manifold to the boost pack, wastegate etc? for splits, cracks, they can get brittle if OE items.

 

i checked they appear to be ok no crakcs.. The rubber is surprisingly soft after being in a Japanese graveyard for a while There is one that broke off of the intake though but someone said that one isnt needed? the ones going to the boost solenoid etc are fine though I think it comes from that cluster of solenoids to a resonator in the intake after the maf

 

I fixed this broken fitting on the resonator and hooked the wastegate cluster back up to the resonator and still have the same issue. I didnt notice any cracked plastic on the intake track.

 

try a dawes to take control away from the solenoid.

 

Sounds like coil packs to me, they could have hairline cracks or look like this...Damaged Coilpack

 

agree sounds like coilpacks.. they are not always visually damaged they break down inside due to the heat cycling..

Simon

 

Ok I guess thats next on the list. Ill have to convert to USDM wrx coils and see what happens. Thanks

 

Just converted to the new style coils and everything is working perfectly! Thanks for the help!

 

This proved to be true in my case as well.. I took the rubber boot of each coil as I replaced them and none of them showed any sign of cracking or fatigue in the plastic etc.. Thanks again

 

glad you sorted it