Hey guys. Struggling pretty hard on figuring out this issue so I thought I’d come in here and see if anyone can lend a hand.

The car is a full race prep 91 civic with a d16z6 motor swap. We went from a d15 to a mini me swap, to the d16 with no issues. We had been running the d16 motor for a few seasons without issues. We are running a stock p28 ecu with a Rywire jumper harness. We spliced in harnesses for the oxygen sensor and vtec and distributor.
Here’s the issue we have. At high rpm, and intermittently, it’ll lose power. You can floor the accelerator and the rpm will slowly come down but not up, and if you let off the accelerator the engine will lug the rpm down to idle. But as soon as the rpm’s drop to idle everything goes back to normal.
It also seems to be timed- for instance around Sonoma raceway I can nearly predict when it’ll happen. If I let the rpm drop to idle in my brake zone, it won’t cut out. But if I don’t let the rpm fall, it’ll cut out in the same spot every time. It’s not throttle position related, and there is no specific rpm other than being over 6k.
We have tried various oil weights, swapped in 3 different distributors, replaced the oil pump (as part of a rebuild), injectors, vtec solenoid, rewired the harnesses we spliced, and swapped com’s and the issue persists. Any info you guys can throw my way is EXTREMELY appreciated. Thanks guys.

 

Have you measured the fuel pressure and tested the FPR?

Are the MAP sensor readings as expected?

CEL codes?

 

Map sensor reads correctly.
fuel pressure is good at idle and under snap throttle. I don't have a way of checking fuel pressure on track in real time and its not exactly street legal to test off track.
FPR was changed and problem remains.

Ill check for codes and report back. CEL has been on since day one. Im sure there are several codes in there since we've removed all the emissions hardware.

 

Kinda running into the same problems. When I've first swapped the motor into the car there was no issue when I was trying to break in the motor. Did 2 pulls after breaking in motor just to hear that vtec scream and it seem fine like everything was running like a champ. After a week I took it out to Do some pulls I broke my driver side motor mount and havent replaced that till 2 weeks later. But after some pulls, the following next day I gassed it up to 6-7k rpm it would Bog. 1st through 2nd gear. Replaced the mount thinking itll solve the problem. Unfortunately it didnt. When I accelerate it seems like I'm losing power. Oil comes out from my driver side valve cover. What can be the problem??? If you want videos of how it runs Message me messenger
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