Help needed

Im a newbe from Australia on this forum thanks for having me

I have a my09 spec b with basic bolts incl vf 52 stock IC

Car was running dreamy until recently

Recently under wot the car misses and backfires. Normal throttle and it is ok

Same in i s or s#. Blows black smoke like fuel gets in but cant burn it up

The more you give it the worse the car runs. Cant overtake as the power is lost etc.

Mechanic discovered issues with cyl one and two?? (well the front on either side were having trouble when he logged it.

Spark plugs were changed earlier but no difference

Air flow meter changed no diff

Coil packs replaced and still no change.

Wot it will splutter and misfire and backfire

Mechanic is a good guy but isnt sure what it causing the issue. Maybe a sensor?

 

Anyone else had an experience like this or suggest where to next?

Tia

Tony

Have you done a compression test? Misfires could be something like a burnt valve or low compression.

First off, tell us the car is tuned for the vf52 ?

 

have you done a vacuum leak test ? that should have been done before the compression test.

 

 

If you have a air compressor, plug the hose off the air filter box with a pint size paint can. pull the small hose off the blow off valve, give that hose a quick short blast of air, put you thumb over the hose. Listen for leaks. When you remove your thumb, you should hear air come out of the hose.

Mechanic said no compression codes were recorded none at all so not done. He also said the issue would be constant at all revs if it were compression or valves

When driving sedately there is no apparent issue

Yeah all mods tuned to suit on 98ron