rb25 cyl #5,#6 Rich

[redline racer510]

I have a Stock RB25det(except Greddy IM) and I have replaced spark plugs 4 times already for cylinder 5,6 including properly gaping them. I checked the coil packs which are made by splitfire which don't appear to have any signs of arcing. Could it possibly be that my timing is off or is the IM causing a lack of air to enter the last 2 cylinders. This has been a problem that has haunted me since the swap during idle you can hear a faint misfire and this is problem is driving my up the walls. Can anyone help please?

[BlewByYou]

I would bet its that intake manifold. Is It a Knock off? Pull it off an port match it.. Timing would affect all cyl..

[96Turbo]

how do you know they're rich, color of the plugs?

I would check your injector o-rings. If they're leaking, then gas will leak into the cylinder around the injector

[redline racer510]

Yes it is a Knock off. The plugs for cyl 5 and 6 where much darker than the rest. I need to check injector o rings.

[96Turbo]

does the fuel rail line up fairly well with the manifold? i had an freddy manifold on my RB, and the fuel rail didn't line up for shit. The rubber rings that are supposed to seal the rail to the manifold would allow air leaks (which would cause it to run lean, but still something you should check).

unbolt the fuel rail from the manifold, and turn the key on so the fuel pump primes. This will pressurize the fuel rail. Look at the tips of the injectors to see if any fuel is dripping out. If you see any leaks, replace the o-rings on the fuel injectors

[redline racer510]

Will try to inspect fuel rail for leaks and i will give you an update. And I don't have any problems lining up the fuel rail with the IM.

[redline racer510]

Checked my fuel rail for leaks and after cycling the key on and off about 4 times I don't see and leaks and i even used a piece of paper towel to see if there is any fuel that I cant see and nothing. What do you guys think i should check next?

[OutToWinPAHC]

I'm not a fan of those coil packs, but I would move them around and see if your notice a change. Cylinder is always the one to go first, I wonder if you seeing oil blow by on the plug and not fuel.

[redline racer510]

I really hope its not blow by and I tried moving the coilpacks around and it is always the last 2 cylinders. Now that I remember when I did my compression check the last 2 cylinders were at least 10 psi lower than the others i think it was like 145,150,155,150 140,137 but the fsm says its ok if its within 20% difference. I really hope that my piston rings aren't responsible for the rich condition and small misfire. It is a really faint misfire (doesn't happen all the time)and when i come to a stop i can smell gas(smells like its running rich)BTW its not an oil film on the plugs its just soot like some one spray painted the tips of my plugs with flat black spray paint.