i'm running full decat, and i failed my emissions, so i borrow exhaust from a friend to pass.

so... on my next MOT, i took it to a different MOT'er and put in fuel injection cleaner - as one of its claims is better emissions... and it passes!!

however, i notice after i put in the injection cleaner, that it doesn't boost as fast as it should. so i reset my ECU, the boost comes back to what it was. also, the injection cleaner dampens the power off-boost too, which comes back after the reset as well.

so, does this sound plausible?

that fuel injection cleaner helped my pass MOT emissions?

somehow it cuts the power - and therfore emissions

maybe a kind of limp mode?

looks like on rom raider, IAM changed to IAM 16 after reset - was IAM 15 before when it got MOT'd (don't know if relevant)

so anyone have any input?

 

Sounds more like the mot'er just passed it anyway.

 

IAM will only really drop if there is evidence of knock/poor fuel so it could well be the injector cleaner caused that, to be honest though iam drop from 16 to 15 would be barely noticable compared to say 4-8.
Fill her up with fuel, reset the ecu and go out for a drive again and see how it goes now.
What year and model are you driving?

 

i don't know how MOT emission testing works, but after the injector cleaner, it was DEFINITELY producing less power - both on and off boost. and the injector cleaner was definitely the cause of the lower power...

wouldn't the lower power give out less emissions?

it's an 05 spec c.

 

Strange one, you really shouldnt have to run any additives to pass the mot with a regular catted system back in place. My Stage3 wrx passed its mot with no cats whatsoever (01 model so doesnt have to have a cat in place), emissions were perfectly normal.
Have you still got the catted system on?

 

no, sorry - i took the cat exhaust off after the first MOT, forgot to mention that... with a cat, it would pass no problem.

i meant decat was back on when going for second MOT, but with the fuel injector cleaner bumping the power down.