Rb20det strange misfire

[Huriel791]

Hey, i'm new in the forum, I have an Rb20det with an electromotive tec3r ecu. A few days ago the car started to do a misfire while in idle. This misfire only starts when the car revs to wards 4,500-6,000rpm when it goes back to 900rpms it stays nice for 5 to 10 seconds and suddenly the misfire starts, its stays for about 30 seconds and goes away. We have cheeked everything related to fuel/air components, Sparks, sparks plugs , ignition coils, fuel injectors, fuel injectors connectors, but nothing seems to be the problem. We did a compression test, 4 of the cylinders gave 145 and 2 of them 125. The strange thing its that in the dyno it gave 308whps at 21lbs and nothing went bad just in the idle as always . If any of you have gone trough this and found an answer to it, i would appreciate any information for the sake of solving this idle problem. Thanks in advance.

[Carl H]

are you using the electromotive coils?
where are you located?

[Huriel791]

Yes i'm using them, but they doesn't seem to be bad. I was wondering if it could be a ground problem or something similar. Either way ill be using my friends coils to verify them. I'm from Puerto Rico thats in the Caribbean Islands.

[Huriel791]

We tested the coils today, they were all good. But we noticed that the car puts up temperature when you rev it up in 5th gear from 80°C to 95°C. So we suggest a bad head gasket. As it picks up pressure trough 5,000rpm and 7,000rpm it leaks a little of water to the pistons an thats when the idle starts, as soon the water is out of the pistons the idle ends. Thats our teory.