Misfire or backfire on gear change

[93R33gtst]

Hi all im having an issue with my r33 gtst rb25det it has a misfire/backfire when i change gear its doing my head in an im not sure where to go from here if anyone has any suggestions that would be epic.

 

1993 R33 gtst

*new plugs

*splitfire coil packs

*walbro 450

*fmic

*gfb bov

*hks mush pod

*3" exhaust unsure what it is tbh

 

Thanks in advance everyone.

[turb33gtst]

What heat range are your plugs and what gap?

how much boost are you running?

No vacuum leaks ?

[93R33gtst]

Plugs are at 0.8 ngk i cant remember the particular numbers have search for a vac leak and nothing about 11-12psi boost

[turb33gtst]

Backfire under acceleration or deceleration ?

 

[turb33gtst]

Tried cleaning the MAF ?

CRC MAF cleaner is the best for that.

[93R33gtst]

Deceleration and yes mate thats been cleaned

[turb33gtst]

not uncommon to backfire under Deceleration my S2 does occasionally when slowing down

[93R33gtst]

Oh..... it happens every gear change everytime unless im extremely soft accelerating

[turb33gtst]

ouch hmmm

[turb33gtst]

Charcoal canister still connected

[GH05T]

i had the same thing. im not sure which fixed it but i had my AFMs resoldered and had the car retuned.

try resoldering the AFM solder joints (how to on here somewhere) cos its cheap and easy to do. and it sounds like a rich issue your having anyway.

[admS15]

Is the bov plumbed back or atmo? Atmo could be a problem.

[93R33gtst]

Bov is vent to atmo

[KiwiRS4T]

There you go. Return BOV to stock or plumb yours in if it is possible. MAF is measuring air coming in and adjusting fuel to suit but some air is escaping via BOV instead of beng recirculated as per the stock set up - hence running rich.

[defari]

Run the flamin mongrel rich buddy.