I own a 1998 Type R Sti ver4 and have two questions. I have fitted a full decat with k&N panel filter also vent to atmosphere dump valve was fitted when i bought the car. I run the car only on Optimax and have noticed its seems to be backfiring when coming of the throttle especially when the engine is up to temp is this normal.

Secondly if this is fuel over run will this be causing problems with the engine in bore wash. Have a mate told me to get it sorted, and will this also create the exhaust flashes that some people are talking about on scoobynet.

 

There is an overrun fuel cut, but it's only active above a certain rpm, which can be as high as 2200. But until you actually hit zero throttle there will be fuel going in the engine, and as you correctly say, it's worse with a VTA dump valve.

If the valve is adjustable you may be able to tighten it up somwhat to only vent the worst of the air.

But a recirc vavle would be my preference.

Paul

 

Thanks Paul havent a clue what sort of valve its got. I am currently looking at getting the ECU changed to a Gems and also changing my Fuel pump will that have an affect.

 

fuel pump effect will be marginal, GEMS will sort it all out.

 

Great thanks mate