Backfiring On Decel - B18CR...

[iijjee]

I have an EG I do only 7 or 8,000km in per yr. I drive it 4 or 5 times a week but not many kays. I recently changed pugs, oil, fluids etc b4 a hillclimb and the car runs a microtech stand-alone ECU. Noticed after the hillclimb the car was backfiring on zero throttle between 3500 and 2500rpm on deceleration. Has also started stalling when cold and idling. I doesn't really bother me too much, a bit of snap crackle and pop, but was wondering if it might be a spoiled 02 sensor or something fuel or fuel pump related. I know I could fork out for a full diagnostic tune but 'round here that's a 4 wk wait and a couple of hundred bucks for a possible no cure. Ideas???

The car is running beautifully in every other way and making excellent power for a NA 1.8! I always keep the tune on the rich side of things but it's never been like this before.

Anyone else had microtech b series experience. My old H22A was a dog for idling and warming up on the same computer, but this setup has been fuss free and like a OEM ECU with a cherry on top!

[tiksie]

You getting any CEL's ?

[iijjee]

CEL? If that is a red light on the Microtech, then, yes.

[iijjee]

Ahhh, Check eng light? I didn't sleep last night... No CEL. (Penny drops!)

[tiksie]

Hows your plugs ? Are they wet ?

Could be load of unburnt fuel due to faulty o2 ?

[iijjee]

Pretty sure the CEL would only work if the stock ecu was connected. Plugs should be fine. Went hillclimbing again today. Won my class by 5.5 seconds with a 31.190!!! Still backfiring... Still stalls on cold start. Still running rich but very well!!!

Still looking for ideas!

[TODA AU]

Play with the Decel Cut value, around 25"~24" is about right but if it's tuned in normal mode & the cruise trim is at the default 16" you'll have issues.
Otherwise if it's in matrix, you'll need to look at the 30", 25" & 20" sites at 2500, 3000 & 3500.
Don't worry about your O2 sensor, it plays no role.
Re cold start, to get the microtech starting real nice, you should have a thermostatic bleed bypass valve fited for high idle when cold.
Plus the ignition & fuel trims vs coolant temp need to be spot on, the adjustment is quite coarse but it can be made to work quite well.
But without a means of additional air, you're fighting an up hill battle,
Hope that helps.

[LowEk]

your running microtech man it may need another tune... and microtechs dont have idol control unless you have the idol speed control unit for the microtech... my bros evo runs microtech and sometimes his idol can sit at 2k and others it can struggle for 800rpms... not that this is bad cos he runs 272 deg cams so it sounds really loud and tough on idol...

take it to your tuner to have it checked..

[geeang]

I had these exact symptoms (except for the huge backfiring - mine is mediocre all the time) - but it turns out I had bad spark plugs - whacked in some Iridiums (correct part this time) and solved ALL my problems; rough idle - dying when cold - struggling when cold etc.

[VT3C]

your running microtech man it may need another tune... and microtechs dont have idol control unless you have the idol speed control unit for the microtech... my bros evo runs microtech and sometimes his idol can sit at 2k and others it can struggle for 800rpms... not that this is bad cos he runs 272 deg cams so it sounds really loud and tough on idol...

please if you going to give some technical advice, learn how to spell the word you're using..

idol = or

...you're looking for 'idle' which means 'not doing anything - just ticking over awaiting effort etc.

sorry to bring up this point but it just bugs the hell out of me and is getting worse and worse on OZhonda forums !!