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Hi everyone,

I've been lurking in the shadows reading posts and completing repairs on my 1995 TF 4 door 2.6L (Australian model) but I'm bamboozled by this odd backfiring issue it has.

Issue - While under slight load/soft acceleration it backfires when between 2500 - 2900 RPM. At no other revs does it backfire.

Setup - 2.6 4ZE1, 5 speed, Redback header, 2.25" exhaust, no cat or 02 sensor. I think this truck was produced just before the cat/02 was mandatory?? The vehicle has 310,000km on it thus far.

Maintenance/troubleshooting thus far - Timing belt/tensioner, valve lashing, MAF clean, plugs, wires, cap, rotor, ignition coil, air filter, done at 300,000. All vacuum lines, rear main seal, fuel filter done at 280,000km.

History - The truck pulls hard and responds to throttle well. I drive 70ish km each day to and from work over a small mountain pass where I spend most of the time in 3rd gear between 3-4000 RPM. I average just above or just below 12L/100km. I have only owned the truck for a few years and it has always had this odd backfire issue.

Any thoughts or advice is greatly appreciated.

Many thanks,

Phill

Double check the no 02 sensor. The efi should be using this to set mixture even without a cat. Engines of that vintage often had air pumped into the exhaust to control emissions. (I think the only effect was more gas out the back diluting the nasties) Normally I would suspect spark but that should be worse at higher revs or load