My scooby backfires on a fairly regular basis. Usually on the overrun but sometimes when changing gear. As far as I am aware it is a standard ECU, Sti 3 VLTD with an hks induction system and dump valve with magnex back-box. Does the backfire mean it is running too rich or is it just a characteristic.

cheers Scott

ps i am happy with the sound if it is not an indication of a problem or if it will damage the cats.

 

Hi Scott
I dont know the technical explanation but I am sure the dump valve is making your car backfire. I had one on my Sti 4 Type R and I would get crackling and popping all the time. It sounded good but I was not sure it effected the performance so I took it off. Almost all the noises them stopped. I am sure someone will offer a technical explanation to why this happens, I think the dumpvalve alters the fuel/air mixture.
Thanks
CJ

 

The ECU determines how much fuel to send via readings from the mass airflow sensor. When the BOV dumps everything into the atmosphere during off-throttle situations, there's suddenly a lot less air going into your manifold than that reported by the MAF. The ECU still sends fuel for meant for more air (because it doesn't know there's less now) and as a result, you run overly rich for one instance. Backfire is a common result. If you can live without the cool sound, pipe the BOV back into the intake. If not, get an aftermarket ECU to take readings from your MAP sensor and decide fuelling from there.

Regard.

 

Thanks for the replys guys. Do you think the popping is likely to cause any damage or will it just cause a the vehicle to be slightly more fuel hungry.

thanks Scott

 

Call me sad, but I love it. Gets rid of tail-gaters on the Motorways !

Damage ? Dunno but I've got a very black tailpipe ! Its been doing it for yonks so far with no problems.

Would the popping put additional strains on the turbo ? The rev counter bounces on each pop ~ sometimes by 300 / 400 RPM.

 

Read you post with interest as my V5 Sti does exactly the same with HKS inlet/back box and Blow off valve on it.

Funny thing was that it didn't do it before i had the ECU reset (after being forced to gently run it on Regular during the fuel crisis)

Do agree tho - love the noise!

Rus