Heres the deal, i got a 90' 240 with the sr20det swap, it ran awesome for monthes, then i put a no cat three in exhaust on it and had the turbo rebuilt cause the seals went and was fillin my intake system full of oil, ran even sweeter i was lovin it! Then one day i got into it to fire it up and it would not idle. It seems to run decent warm over 2000 rpms, but below that it pops sputters backfires out the intake and all kinda nasty stuff. I did a compression/leak-down test on it and it came back all good. and my ecu is showin 55 which to my knowlege is all clear. At this point i really started to get stumped and i went to freshalloy and got some pointers and people told me to clean my IACV Valve. So i did this and is wasnt all that dirty but it was dirty enough to MAYBE cause problems, so i cleaned it. While i had the upper half of the intake off i noticed that intake port number 3 was all crispy and burnt on the inside. Other cylinders were starting to show signs of this but 3 was just really black. I was like ah ha! i found my back fire through the intake but why would it be doing this, might i have a sticky lifter? or something...my very uneducated guess is that the intake valve(s) in that cylinder are hagin open during the compression stroke and shootin fire back out..i think it even cracked my intake to intercooler pipe, its plastic but still! Is it timing or do i need to get into the valve cover? Any and all suggestion would be appreciated...Thanks guys

 

switched up the closed thread at your request

 

Thanks for the speedy switch!

 

is there anything in the ignition system that can cause this? I have good compression and did a leak down test and all cylinders are good and within 1 or 2 psi of each other.....