ey guys,

The other night i went for a bit of a spirited drive, having not driven it for a month.

Was going along, got to about 4k RPM when it felt like the engine backfired. There wasnt much of a sound, just what sounded like a little crackle from the exhaust. Like a single pop.

I recently changed the ECU to a manual one, also changing the ISC to fix up my rev issue.

Any ideas?

more info!

all the best.

was the ecu changed before or after the issue.?
the isc should have no effect in this way.

more info!

all the best.

was the ecu changed before or after the issue.?
the isc should have no effect in this way.

The ECU was changed to that which came from the manual donor car that I used for my conversion. It was done to test whether the old ECU was the cause of my poor economy and rich mixture. Now, I didnt go for a hard drive for a long time before the other day, so I dont know if its been there for a long time or not.

was it just a once off thing?

unless im mistaking backfires are fuel / ignition related how you checked your plugs and leads including checking the dizzy for crap buildup?

wouldnt know otherwise i dont let my cars rev out

Hows the back fire going?


It only happens when running rich so check the o2 sensor. Or replace. About $120 off ebay.

Also check general service items with the ignition.

All the best.

Hows the back fire going?


It only happens when running rich so check the o2 sensor. Or replace. About $120 off ebay.

Also check general service items with the ignition.

All the best.

I'll be replacing the o2 sensor soon enough. Today I let it rev out to 4.5k RPM with no backfire. needless to say i dont generally like doing this, maybe once every two months, so I backed off assuming that it's okay. however, I'll be looking very closely and reporting back to here.

Spark plugs were replaced about 15,XXXkm/s ago but were cleaned/gap-checked when the engine was replaced some 5-6XXX ago. Leads need changing but are still servicable as they're the ones I had when I bought the car three and a bit years ago. Rotor/Dizzy cap are in great condition and are regularly cleaned and spayed with WD40.

Air filter is brand new (replaced approx 3-4XXXkm's ago.

I'm stuped as to why it would backfire one night and be fine the next.

my car back fires. and shoots out flames too :P