Misfire issues under boost, WOT, 5k RPM+

[Coup D E'Tat]

Some background - 2.3l - 185 compression across, 272's, GT30R with a chewed up turbine wheel, AMS 880's, etc. Brand new Accel wires and BPR7ES.

When I bought the car, it came with COP. I have never been a fan, so I pulled it off. I replaced it with a '90 coil, wired in bypassing the tach interface, Magnecores, and the BPR7's that were in the car.

I started tuning finally, and noticed it was breaking up really bad up top. Wideband was pegged rich, so I leaned it out some and bumped some timing, just trying to get a base tune. 11.60:1 now, still breaking up.

I switched out the plugs and wires for brand new units, and swapped in another '90 coil thinking it may be the problem, no luck. New plugs are gapped between .026 and .027.

Is the '90 coil different enough to cause problems? (I was under the impression that all of the actual coils were the same.) Could it be something like injectors?

Something else I noticed, is that sometimes, either starting off or after switching gears, the car will go lean, 16-17:1, briefly, the fall back down (while on the throttle, not the free falling of revs.) The car hesitates during this. I searched and read that some people have had experiences like this with PTE injectors and such, but only when cold. Mine seems to do it at random.

Log 1 - WOT log, 3rd gear.
Log 2 - Cruising log.

 

[JayRolla]

How much boost are you running, what type of fuel. Also what are you tuning with? Do you have any boost leaks?

 

[Coup D E'Tat]

Apologies. I copied/pasted from the 'Link forums, where some stuff is assumed.

93 octane, ~14-15psi, DSMLink, zero real boost leaks. Bleeds pressure roughly 1PSI per 3 seconds down from 20.

 

[JayRolla]

Hmm you should not be breaking up at that boost level. Where you breaking up with the COP? Have you tried different wires just in case. I had the same issue with some new Accel wires and I never would use them again.

 

[Coup D E'Tat]

Yea, I know. I might close the gap anyways to see, but at 51lbs/min around 26PSI on my old SC61-powered 1G, I only had to bring the gap down to I believe .024."

I never tried anything WOT on the COP, but I might toss it back on just to see what happens.

I've always had good luck with Accels, and I tried with a friends Magnacores as well.

 

[Coup D E'Tat]

Gapped the plugs down to .022, still breaking up. Logged PLXWB and battery (battery to check voltage.)

I'm somewhat stumped here. I've read it could be a mechanical problem such as something in the valvetrain sitting properly, but the car runs pretty smoothly the rest of the time.

I might borrow a set of injectors to try out.

 

[Ace_gst]

Has this ever been resolved. I keep running into dead threads and am having the same issue. Changed coil, plugs, wires, fuel pump, filter, maf, injectors, fpr. It does the same dip to 16.5 or lower after shifting while cruising And breaks up at 5k WOT.

 

[bling5tatus]

P T U

 

[Ace_gst]

Nice...that's what I'm on the hunt for now. Thanks for replying to a thread 7 years old also. It's no longer a dead end road!

 

[bling5tatus]

No problem. I try to help people that need it. I've chased my tail with ignition issues a lot so I've been familiar with all the components involved.

The PTU's can be finicky too. I've had ones that are fine when they're cold, go out and drive a few miles and then it runs on 2 cylinders. Running on 2 cylinders is always a "good" sign because it eliminates a lot of things right off the bat. That's how I look at it anyway.

So, if you end up testing a PTU, try to take a spare with you in the car for when the one your testing intermittently fails when warm.

One time I took one apart and removed the gel coating to see why it was failing. I found a very small hair line crack in the board and then it made sense to me that it would be "ok" when it's cold but have a problem when the warmed material expands. It likely warms up from the inside during it's normal operation as well as from the outside due to engine bay temps.