I got a small sputter at 5000 rpm and anything higher

[dsmoverboosted]

Well I am about ready to seriously smash this car into a pole. I got a small sputter at 5000 rpm and anything higher than. Its not bad but enough to lose all performance past 5000 and it shakes the needle on my boost gauge. My boost gauge shakes before it starts to sputter (@4500 rpm). I say its small because you can barely hear it and it not like running on 3 cylinders or anything like that.

I get no cel's and nothing I do seems to change anything. I am ready to drive this thing into a tree . I have done the following to try try to fix it with no avail.

Swapped the following with known working ones...
mas
coilpack
transistor
plug wires
ecu
cas
and I have bought new 6es's gapped to .028
I hooked a fuel pressure gauge up and the base is about 40 at idle w/o vac, 30 with vac and rises with my boost gauge when accelerating so that should be fine.

I have also boost tested with only a small leak at the tb seal but thats been there before this started happening.

I have the timing set to 5* btdc

physical timing and b-shafts checked 4x's

The only thing I can think of is a bad wire somewhere in the engine harness??? What else could it be?

Any other ideas what else it could be???? I gotta fix this so I can bring my new setup to the track. Right now its nothing more than a nice lawn ornament and go to the store car.

 

[Defiant]

Plug wires.

 

[dsmoverboosted]

Plug wires.

been replaced already

 

[dsmoverboosted]

Any other ideas ? I am ready to drive this thing off a clif

 

[perley03]

What is your fuel pressure when it starts happening? Clogged fuel filter?

 

[dsmoverboosted]

well the fuel filter is a year old (about 6000km's on it). My fuel pressure is constant from full boost at 4500 to 7000. It seems to rise at the same rate as my boost gauge toping out at 50psi with 10-11psi of boost.

My logs also dont show any drastic change at anytime during my logs.

 

[perley03]

well the fuel filter is a year old (about 6000km's on it). My fuel pressure is constant from full boost at 4500 to 7000. It seems to rise at the same rate as my boost gauge toping out at 50psi with 10-11psi of boost.

My logs also dont show any drastic change at anytime during my logs.

That is good, the FPR is doing its job. I really don't know what else to tell you, other than to check every connection for a loose wire. It looks like you covered everything else, and if I were you, I would be stumped as well.

EDIT: Just a thought, you mentioned you are on 6's for plugs. Try going to 7's, gapped at 0.025" and see what that will do. It will be a colder plug, but lowering the gap will be fine, maybe its too hot and throwing a misfire every now and then to screw things up. Had this happen on a sled a few years back, swapped colder plugs but smaller gap, and I'm still running on the same plugs and over 1100 miles.