Help please...4200 failed emmisons

[Tom4200]

Aside from emmisions formalities the mot tester checked the car out fully underneath it's in fantastic condition and there is nothing else wrong with the car!

 

[CatmanV2]

We live and learn

C

 

[allandwf]

Do what the TVR folks do, have MOT cats Then resort back.

 

[Tom4200]

It's probably running better being more free flowing lol!

 

[alfatwo]

Do what the TVR folks do, have MOT cats Then resort back.

Thats not a good Idea any longer as It's illegal and will also void your insurance...

Dave

 

[2b1ask1]

There is no lambda sensor after the secondaries so their removal won't throw an error. but they are there to do a job at cleaning the gasses up...

There was a complete OEM system up on fleabay last week, may be still about £400 I think.

 

[jayblue]

Time to resurrect an old thread for some advice! Took my GS in for its MOT today and it failed on emissions. My car has US spec manifolds with the cats in the headers and Supersprint decat pipes which i recently fitted to replaced the secondary cats.

It passed the natural idle test ok but failed the fast idle tests with readings not dissimilar to the ones Tom got in post #1 of this thread, blowing 650 on the first fast idle test and 530 on the second one. The lamdba reading was also a fail on the first fast idle test, but not the second one.

Since i bought the car a year ago i have had two emissions warning lights on the dash, both of which flagged the code P0431. Once i did a battery reset in both instances the light went out and the car has no current running issues. The secnodary cats were in very good condition when removed from the car. Any suggestions as to the source of my woes?

 

[Gp79]

Did you find the problem and pass the mot in the end?

I am considering gutting the secondary cats but dont want the same issues / hassle come mot time.

Thanks

 

[jayblue]

Did you find the problem and pass the mot in the end?

I am considering gutting the secondary cats but dont want the same issues / hassle come mot time.

Thanks

Took the car to my specialist for a service and MOT on Monday. He rang today to say it passed the MOT just fine and he didn't ask any questions about the emissions so it is a bit a mystery why it failed the first one. Incompetent tester maybe or incorrectly used equipment?

In any case its a relief and a reminder to always take the car to the people who know them best rather than the garage around the corner. The secondary decats are a great mod, easily added many smiles per mile to the car - go for it!