High Exhaust Emission + Hoigh Idle Speed!

[Williboy]

Went for a MOT today and failed due to high CO2 emission (double the limit!) and a high resting idle speed.

I have the following mods, anyone with a similar story?

99 reg

45k miles

supercharger

pre-cats removed

standard main cat

prolex exhaust

otherwise no other engine mods

no exhaust warning lights on either

Took the car in for a diagnostic and they said it wasn't due to the engine management. He recommended me to put the pre-cats back in and then re-test. I just wanna ask you guys if anyone has had a similar problem? Is this guy talking crap or is it true?

To be fair, I went to the same guy last year for a MOT when my car didn't have the supercharger and pre-cats still installed and passed no problem.

I dont really want to get new pre-cats fitted as i spent money getting them removed in the first place!

Spoke to Mark at Tdi and he said you have to really warm up the main cat, (didn't seem to help tho today during the re-test).

Also, the resting idling speed has increased even after a good spin in the car, does the supercharger cause this?

What do you think i should do, get new pre-cats, change main cat or is it something else?

Anyone know where i can get an emission test fro free?

Lots of questions i know, but really need help as my tax disc has expired and so need this :tsktsk: MOT certificate!

[Gord]

With your pre-cats gone the main cat, as Mark says, needs to be very hot B4 YOU TEST FOR MOT :D i know place that you can test your emissions but its just outside of Manchester :D clean your air filter toooo :D

[ColinBarber]

what was the idle speed?

[Steve ( West Mids )]

and turn the air-con off ...............

[Dave-Ellen]

Mine was same as yours and scrapped thru

Mark is correct in that you need to go for a good high speed run before testing.........

[Williboy]

The idle speed was about 100 rpm over?!! The guy said he can adjust it to pass the MOT but the main problem still lies with the high emissions. Even though i get the cat really hot, there's no guarantee that they'll test the car immediately when i drop it off. May sit there for a few hours? Wouldn't i get the same problem if i went for a performance manifold as opposed to just taking pre-cats out?

Solution anyone?

[ColinBarber]

you are not meant to adjust the idle speed. The ECU should take care of it. Sometimes you need to let it idle for a period of time for it to adjust. If it doesn't then there is another problem like a dirty MAF sensor, throttle body or idle control valve.

[Williboy]

anyone still have their pre-cats i could buy?

[Lexus Jim]

your car still should pass the mot with s/c and pre-cats removed. There must be a problem with the engine (see Colins post) take it to another garage