1G Missfire Under Boost

[garrek11]

Ok long story short car was cutting out under boost 30+ psi so I installed a ARC 2. Got everything running good Cruise/Idle go to hit boost and it does the same thing.

Short list of mods
Built block / heads
Super 94 turbo
Walbro 450 feeding A1000
Speed Density
etc etc

Things replaced / Checked with known good working parts
coil pack
Spark Plugs gapped to .022 and or .020
Spark plug wires
Ignitor
fuel filter
FPR
Boost leaks
Compression and leak down test


What could I check next? Ive been told it could be a bad lifter or rocker?

 

[boostdawd]

What type of spark plugs are you running? Have you tried using br8es? Not the bpr8es. I had a similar issue at 25psi where it will stumble/hesitate. Gapping them different did the trick but was recommended to us the spark plug without the "P"

 

[garrek11]

Im 90% sure br8's one thing I did notice when switching from taylor made race wires 10mm ones back to ngk wires was the misfire wasnt as violent with the taylor wires vs the ngk's. Sounds like im hitting 2 step on the ngk's.

 

[toddrs93]

Are you sure you are spot on with the AC2? Fuel Pressure staying OK and wideband reading up to the point of the cut out?

 

[GST with PSI]

I was recently having some issues with ignition breakup near redline. Someone suggested I try iridium plugs, which normally I would never even consider. However, desperate for any solution, I swapped in a set.

I went with a set of NGK BR8EIX plugs gapped down to .18 and have had zero issues since. I also updated my COP ignition system with all new components. You should be in the same boat since you just installed the ARC2.

http://www.dsmtuners.com/threads/gstwithpsis-galant-vr4-1837-2000.482807/page-6#post-153587328

 

[gofer]

Ok long story short car was cutting out under boost 30+ psi so I installed a ARC 2. Got everything running good Cruise/Idle go to hit boost and it does the same thing.

Short list of mods
Built block / heads
Super 94 turbo
Walbro 450 feeding A1000
Speed Density
etc etc

Short list is an understatement on a DSM running a Super 94 turbo, build a profile when you've got time. Asking for help with that list a mods forces us to give you bad advice because we have no idea what's done to your car. --->Create A Car Profile<---

 

[garrek11]

Ok sorry I updated my profile.

ARC 2 seems to be fine idles and cruises fine but there is no real way to tell if its doing its job during boost. Wideband is logging just fine until it breaks up and it throws a false lean. Only reason why I know its a false lean is because my plugs are jetting. One thing that I did find today before work which gives me hope is my car might be tuned for the wrong MAP sensor. Previous owner installed and always thought it was a GM 3 bar but looking closely at it there are no markings referring to a GM # so I messaged the previous owner and he thinks its a 4 bar omni.... Not sure if that will explain my problem or not but yeah.

 

[garrek11]

The only part # I could find on the MAP sensor was 1004B02 and that was it.