Misfire / hesitancy on 01 Bugeye
10 March 2014, 11:58 AM
#1
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Misfire / hesitancy on 01 Bugeye
It's me again - after more advice 
I have been chasing a problem for a while now and may have come full circle
The car has the following mods:
VF28, 550cc pink injectors, STI TMIC, Walbro 255, K&N panel filter, decat downpipe and 'exhaust', std uppipe, FSE/Sytec fuel reg
The car is new to me and it started off with a big stutter underload at WOT.
The car has been given:
New fuel filter
New air filter
New Platinum plugs
2nd hand coil packs
2x Oil and filter changes
New timing belt / tensioner / water pump / thermo
2nd hand MAF
The stutter was tuned out by a specialist but reappeared following day. A few days later the 2nd hand MAF was installed along with a stock air box. This cured the stutter.
The car now has a misfire / uneven running that comes and goes.
Cylinder compression measured as 160psi on all cylinders.
The after market regulator was removed and this made the misfire / uneven running worse.
The car still has the stock regulator installed. The after market regulator is on the fuel return on the passenger side.
Once the after market reg was reinstalled the pressure was increased to 50psi which appeared to improve but not eliminate the misfire / uneven running.
During the diagnostic work it was always possible to get the desired AFRs.
Should the stock regulator still be on or replaced with an adapter?
What is the correct fuel pressure to set on the aftermarket regulator with 550cc injectors and a Walbro 255?
I have digested the contents of the following article but cannot be sure of the answers to the two questions above:
http://www.iwsti.com/forums/2-5-lite...e-2-setup.html
Thank you for any info on how I might sort out this problem.
Korgua.
I have been chasing a problem for a while now and may have come full circle
The car has the following mods:
VF28, 550cc pink injectors, STI TMIC, Walbro 255, K&N panel filter, decat downpipe and 'exhaust', std uppipe, FSE/Sytec fuel reg
The car is new to me and it started off with a big stutter underload at WOT.
The car has been given:
New fuel filter
New air filter
New Platinum plugs
2nd hand coil packs
2x Oil and filter changes
New timing belt / tensioner / water pump / thermo
2nd hand MAF
The stutter was tuned out by a specialist but reappeared following day. A few days later the 2nd hand MAF was installed along with a stock air box. This cured the stutter.
The car now has a misfire / uneven running that comes and goes.
Cylinder compression measured as 160psi on all cylinders.
The after market regulator was removed and this made the misfire / uneven running worse.
The car still has the stock regulator installed. The after market regulator is on the fuel return on the passenger side.
Once the after market reg was reinstalled the pressure was increased to 50psi which appeared to improve but not eliminate the misfire / uneven running.
During the diagnostic work it was always possible to get the desired AFRs.
Should the stock regulator still be on or replaced with an adapter?
What is the correct fuel pressure to set on the aftermarket regulator with 550cc injectors and a Walbro 255?
I have digested the contents of the following article but cannot be sure of the answers to the two questions above:
http://www.iwsti.com/forums/2-5-lite...e-2-setup.html
Thank you for any info on how I might sort out this problem.
Korgua.
02 May 2014, 05:34 PM
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Good news Subaru fans.
The problem was diagnosed as a faulty injector on cylinder #4.
A bit of trial and error with running the car with each spark plug or injector disconnected in turn.
No CELs were being generated.
A new 550cc pink was sourced and problem solved.
The car was then remapped and now sounds and goes great.
The problem was diagnosed as a faulty injector on cylinder #4.
A bit of trial and error with running the car with each spark plug or injector disconnected in turn.
No CELs were being generated.
A new 550cc pink was sourced and problem solved.
The car was then remapped and now sounds and goes great.
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