Please Help Me With Missfire Prob It Only Happens When Under Load I Cant Work It Out Checked Everything

[danny14]

hey guys this is really frustrating has anyone had this prob before , when it sits still it revs out but when under load on the road it just breaks down , i have put brand new coil packs in , changed the plugs for the 2nd time in one week that didnt fix it i got em gapped at .7 i checked all the loom wirng voltages earths cant track it down like i said when it sits still it revs out but when on road it just breaks down

im desparate for help if anyone could please help me out would be much appriciated .

dan.

[paulr33]

check the basics

when did it start

whats changed recently

[blaikier33]

afm mate. mine was doing the same thing, somtimes it would have no throtle at all and just stop. i would wind the engine over and it would fire but wouldnt run.

other times it wouldnt rev over 2 2.5 grand. it would just bounce there violently my tuner and i pulled it apart and fixed it . or u could just replace.

but that is were ide be starting.

[OMGGTR]

Lets say for diagnosis purposes if its not the AFM... what else could we consider ?

[blaikier33]

i was thinking cas but when u disconect that your fuel pump does not work, is it a gtst or gtr

tps maybe..

fuel pump..

[OMGGTR]

scrap fuel pump.. its its something in the combustion process to do with spark... electrical problem.. ( ECU ) ?

[blaikier33]

there is an earth on the fire wall for the coils check that. check them all. iwould seriosly try afm first but. unplug it and plug it back in thats what i did to mine and it would work for a while anyway. if it runs the same with it disconected thats probably the prob. they wont rev past 2.5 rpm disconected

[Chris32R]

If the AFM is the problem (which is what i suspect to be the problem with my car too) does the car run super lean when it loses it's throttle while still revving and also when it missfires?

I've got a forged built bottom end and don't want to do any damage to it.

Thanks