Hi there,
i have a 93 Impreza WRX JDM.
Well since a few weeks it behaves strange,
at about 4000 rpm it starts stuttering until 5500.
Pressure is stable at 0,7 bar (10,8 psi),doesn't spike.
Electrical i can't find any issue, no fault stored no check engine light, nothing.
After some time i figured out that i can control it in some way, if i accelerate with Throttle about 60% open the Problem doesn't occur, only if i go Full throttle, he'll do it.
Mass Air Flow sensor is new, replaced it after the Problem occured.
What i've done until then was a AEM 400 fuelpump, ran fine with it.
as the Problems couldn't be solved by mAF, Spark Plugs and ever goddamn sensor this EJ20G has i changed to a Adjustable Fuel Pressure regulator.
But now im confused, i read something of a base Pressure of 3 Bar (43,5psi).
(Base plus intake pressure = Main Fuel Pressure)

But, as i could find out due to several Afterburns it runs too rich.
The Service Manual talks about a Main Pressure at Idle of 24,6 to 29,7 psi.
With that setting it runs to lean(Oil Themperature rises to Fast when starting cold and driving in normal condition)

Somewhere i read something about different Pressures of early JDM Models an UK/EU Models.But there was no guarantee for correctness, so i looked over to a Subaru Car Seller, who could only tell me the Pressure i already new from the Service Manual(which is for the UK/EU Models).
An Email to Subaru (Germany and Europe) was absolutely Helpless.
They told me to ask a Subaru Dealer(which i already had done and i also wrote it in that mail, dumb a...).Seems there is no one able to write a simple Mail to Japan.....strange in a World full of Modern Communication Forms.

Here in Germany, the Subaru Drivers are pretty rare, if you search for Information you get mostly very expensive rumors, told from People who don't know much, just heard someone telling it.....

So i hope Here is someone Who can help me with that.

Greethings from Germany

Marcel

 

Did you set the fuel pressure static with vacuum off the regulator?

Coil packs are most probably your stutter problem. Uprate to new age coil packs and job done

 

Thats what i mean with Base (Vacuum off) and Main(Vacuum on).
I Tried both ways, 3 Bar with vacuum off at idle.
And 2,1 with vacuum on at idle, like the service manual says.
Coils are new.
Is there a DIY for the newage packs?Its already the second set of packs in about 2 Years, pretty expensive....

 

yeah there is a thread on DIY for the coils. Fairly simple job and future-proof.

 

New age coil conversion How To...

http://www.jamessimpson.co.uk/classi...ck-conversion/

 

Thanks, thats Great, i thought about a change to newage, but also thought it would be very complicated, but im astonished how simple it really is.


As far as i now replaced FuelFilter i noticed something which came short after changing to that AEM Fuelpump.You can hear the pump when u turn ign on(thats okay, otherwise it self or the cables should be damaged).
But As the Pump starts its short runup, you can hear gurgling noises, everytime you turn ignition on without starting the engine.
As far as i remeber, the old Pump(Walbro 255, found it out when i already had the AEM one, thought there was still that oem one inside as the one told me who sold it....)diddn't do that.Also there was a difference in size of that pre filter.So i diddn't know better and used the AEM one, which is smaller than the Walbro one.

Could there be any reason for my Problem?
Tomorrow, if the weather is dry i'll take that aem one out and have a look at it, hopeful for finding something that might be wrong.

Allthough i'm thinking of heading back to the 255.
Can i run it on E85 with that walbro?(That was the point why i picked that aem one,i was planning for a dual Fuel Setup, and the capacity of 320 liters per Hour by nearly same Price tag)

That AEM was declared as a "without Mapping Plug n Play change", but over time i suspect thats not true, it seems to deliver more than that 255, due to a different voltage stepping.(That was when i had the original Fuel Pressure Regulator until it died(membrane killed, Intake was flooded with fuel)

Hope i got my Scooby back to Normal performance soon, driving in Snail mode is worse.