98 R34GTT 4k engine stumble

[JC71]

98 r34 gtt

Been rocking my latest setup and car running like never before.

Have put a good 200 miles on it since all the latest changes and additions.

everything is dialed in and have been driving it a bunch.

 

However, all a sudden last weekend as soon as I pushed throttle passed 4k and the engine stumbles, (slow or fast acceleration) hesitates and doesn’t go above 4100 or so, like a misfire. Everything else seems fine.

I had a “good” set of coil packs that I removed from car when I first got it when I changed them over to new coils.

I swapped out current ones for those, but no change. I also changed the plugs, no change.

Seems to rev over 4 when out of gear with no load just fine no “misfire”, but as soon as its in gear with a load of any kind, it “misfires” as soon as rpm drop back below 4 k it runs perfectly, smooth, starts, restarts and drives fine as long as I keep it below 4 k while in gear.

All readings look fine, no CEL

 

Any idea as to what could all a sudden cause an issue when pushing rpms passed 4 k?

[GTSBoy]

It's either an ignition failure or a fuel failure.

[Spearzy999]

Hi mate I am having an identical issue with my 98 R34 GTT. The engie suddenly cuts out under load at about 3-4k, black smoke out exhaust. Almost feels like traction control kicking in. No CEL but still going to check codes later today.

Car was sitting in the shed for about 5 months before hand and only idled a few times, took her out with about 1/4 tank, filled up and thats when the issues started happening. 

Threw on a spare set of coils/harness and checked plugs which was no help. Recently had fuel pump/filter changed so surely thats not the issue unless condensation in fuel, I just havent had the time to drain it

It's running a hi flow turbo, bosch 1000cc injectors, walbro 450L, Z32, Nistune etc... All about 2000km old.