[quote=joe p;293163]ovp, wiring harness, oil leaking into plug holes in the head, shorting a coil or, bad coil. (pull it, remove the resistor tip and look for oil in the hole, if it's leaking, it'll be bad now or soon, they overheat and break) dynamic chamber flap (resonance flap) on the manifolds will also fall apart sending rubber and plastic into it, holding valves open and causing it to skip and/or backfire. (pull it and see if the flap is coming apart)



nice one joe! good post!

i was just googling this resonance flap! since i got a problem with my c280 m104 engine 1996 revised engine harness version.

this is my exact problem! there is an lpg conversion on the car and it backfired abliterating the plastic flap! i took it out and there is no flap! it was gone. my guess is some of it has gone into the engine / and some of it is blocking the air flow causing the mixture to be too rich.

as a result the car now back fires a little running on petrol. the revs just drop sudenly, but only a little! i have been having huge backfires on lpg. now just running on petrol. changed some coils over from my e36 amg m104. and replaced the relay. but found out that the relay is already the 000 540 6745 one! waste of cash that was! tomorrow im going to take the air manifold apart and see if there is an obstruction! would anybody recomend doing more work than this? i.e. taking the head off to see if the valves are ok?

plugs are fine changed 4k miles ago!

air mass meter was swaped from my E36, definetly the problem lies with air obstruction. what exactly is the job of the resonance flap? idling issues? or better engine talk?

i know this post is few years late, but would appreciate any reply.

many thanks

paul