for about a year now my sir-g motor has been having idle surges about from about 700-1200rpm at idle. its an on and off process, it could surge for a minute or for five minutes and then idle normally. some days it doesn't surge at all. i replaced my iacv with a working one from a friend and problem still goes on.
and for a couple of months now my motor has started having a lot of backfire when i engine break, i did a full tune up back in oct/nov last year so kinda puzzled what could be the problem.

anyways my setup:
jdm b18c sir-g
skunk2 68mm tb
skunk2 intake manifold
dc sport header 4-2-1
2 1/4 catback

unknown ecu due to serial code scratched off. i took it to a reputable local hondata tuner and he tells me its a virgin b16 ecu. thing is if it is a b16 ecu wouldn't it run lean on a 1.8 motor? so what can be the cause of the backfire?

do i just need a tune? thanks for any helpful advice in advance

 

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I'm not sure about the backfire, but as far as the idle surge....check the idle screw. Take it out, clean it and reset the idle. You have to unplug the IACV when you reset the idle. I've seen a lot of older Hondas with carbon built up around the idle screw. Also make sure you have some play in the throttle cable and make sure the butterfly on the throttle body is sitting flush against the housing. Perhaps this will fix the backfire. I recently was using Seafoam on a stock 96 DX and it backfired a couple of times. The car was running terrible and I later found out the coil was going bad. I know you've been driving it for a year or so in this condition, but how's the quality of the spark? Just taking a stab in the dark. If you're not getting complete fuel burn then you'll get a backfire as a result.

 

i've reset the idle screw before already so thats not the problem. the tb/manifold were new when this problem arose. after driving the car for about a month w/ the tb/mani the surging began. using an itr tb cable and it has good play. i'll check the butterfly when i get the chance. i use seafoam as well every 3k miles or so. i've replace the coil/plugs/wires/cap/rotor in oct/nov. but i'll take a look at the plugs condition though.

thanks for the information

 

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