back firing p38 !!!!!!!

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andrew j

New Member
put a new crank sensor on today with a new maf the only thing it wants to do is back fire down the exhaust ive got spark etc ( its not gassed ) if the ecu and becm weren't talking surely i wouldn't get spark etc and would the cam sensor cause so much grief ? all the threads and links ive looked at seem to say no it would only slow the starting process . all the symptoms point towards the timing being out,as if it had a distributor. if you can make sense of this. bloody annoying . any ideas anyone??????
 
i fitted new plugs and leads before i changed the maf and crank sensor its driven me round the bend i had it checked last night thats how i changed these told they were dead it doesnt even show its cranking on the tacho then you get it poping down the exhaust it feels as if the timing is out obviously it can't (?) be . the only thing i haven't done is wire brush the tangs on the fly wheel is this my next move ?
 
i keep thinking that , but ive gone ( looking from the front of the motor )odd bank my right , even my left, i put the leads from coil packs to corresponding pot , i was thinking maybe the tangs have corroded somewhat and they are not giving the cps enough of a "pull " magneticaly if you can see what i mean ?
 
you could try it, dont see it doing any harm, also try the coil pack, its numbered, recheck leads and also the leads at the back of the block on the passenger side, you might need a mirror and torch.

i'm not sure how it connects with original problem, is it still the same, not firing on one bank only? i think they work on the principal of redundant spark, 4 coils and 8 plugs, i would assume it would miss on both banks if thats the case. is it random pots or the same each time?
 
baffling aint it ! couldn't tell you if its only one bank now bugger wont try to start , just pops down the exhaust when it feels like . ive cranked it to god knows where and back its also connected to my disco so i know theres enough batt power the coil plug feels and looks solid and tight ive got continuety thru the coil wiring ive even moved the coil positions in the cage (admittidly before i changed the bits today but even then it would only fire on 3 cylinders my thread 137 hot etc ) so you could very well imagine how i feel ive had a guts full of pulling my trousers up and down :violent: p38 when this ones done never again:boink::censored: ill buy a push bike first even if it was for free !!!!!!!!!!!!!!!!!!!!!
 
you have sparks though? on mine i got the coil pack connections the wrong way round and it wouldnt fire at all, dunno if this helps you as i think you have spark!
 
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