backfiring
 

I got a 88 tII, e6k haltech, ais meth kit running pure meth & running all trailing plugs.

Car has been tuned by myself this summer and has been running very good. I stopped driving it when it got colder. I decided to drive it to work today because the roads were clear and decided to hit some boost on the freeway onramp. when i hit full boost the car would pop (heard it through the wastegate). AFR's were in the 11.5-11.8 range. Car has never done this during the summer. a friend of mine has a t2 with a haltech e6k with a hybrid turbo that started doing the same thing. To me it sounds like the cold air but i dont see how if it doesnt show it on the wideband. I also thought of my meth kit along with the cold air made my combustions temps too cold causing spark blowout? Couldn't be it if my friend that has no meth has the same problem. Has anybody has this issue?

??

any reason why im getting no replies??? thought we had some smart guys on here?

Maybe it's Christmas time and all the smart guys have better things to do? :)

What boost are you running? 11.8 is pretty lean for anything over 10 psi, even with methanol. What is your ignition setup?

Two things happen when the intake temp is very cold. One the charge is just more dense and dynamic pressure will be greater. That makes it harder for the ignition to jump the gap of the sparkplug. Two, fuel will form a homogeneous mixture more easily when the air is hot. As it gets colder it's easy for fuel to fall out of suspension. When that happens it's easier to get an incomplete burn or misfire.

ok...

Car worked fine before with intake temps as cold. Im still running stock ignition with all 9's all around for plugs. I know im due for upping the ignition but i know something happened differently because it worked fine before. Im going to change the plugs as they have been in there for 5-6 months. as for boost, im currently running 20psi on a t67.

Thing i notice after driving it today was that it only does it under heavy load (16+ psi) and its more of a consistant cutting out sound that i can hear through the wastegate. AFR's dont change at all when this happens, this is what gets me.