Massive CO level jump from last years MOT now @ 8.04%!!!

Tony Harrison

Tony Harrison

Member +
Hi,

Hope the technical know its can help me on this, since the last MOT my motor has covered 2500kM, and last year my CO level was well within the 3.50% max.

Now I have not done a thing to the car since then that would have upset it it such a way. So my asking is this?

What would cause it to give out such a high reading?

Lambda sensor?
Coolant temp sensor?
Any other sensor that doesn't sensor anymore?

Any useful feeback will be received gratefully.

Cheers Ty
 
Jay

Jay

Admin
Take a good look round your vacuum piping first, last time I had a reading that high it was because the aftermarket boost gauge was leaking where it connected to the MAP sensor piping. Knocked my emissions for six.

Jay
 
Tony Harrison

Tony Harrison

Member +
weeJohn, thanks that one too!

Had a thought last night. Could the fitting of a uprated fuel pump cause this? Am I right in thinking though that the FPR would have issues to do this not the fuel pump in this scenario? I havn't fannied about with the FPR just to clarify.

MAP sensor? Would that be a cause?

Ta muchly
 
Jay

Jay

Admin
Fuelling will have a direct effect on emissions. If you are uber rich you will be uber high in emissions.

What sort of modifications are on the engine?

Jay
 
Texx

Texx

Super Moderator
A high CO reading is the direct result of either excessive fuel or insufficient air. Assuming the air intake isn't blocked or restricted in any way it's probably safe to assume the problem is too much fuel. You should be able to pass the non cat emissions test by reducing the fuel pressure at the FPR, however it would be best to reset the ECU before doing this as the long fuel trim values can cause issues. Once you've got your MOT certificate, turn the fuel pressure back up to at least 2.6BAR (vacuum hose disconnected) and have the fuelling checked by someone with the necessary equipment.
 
Tony Harrison

Tony Harrison

Member +
Hi,

As far as the mods that could affect it, are

-uprated fuel pump (which I fitted earlier this year)

Everything else was EXACTLY the same as when it was tested last year. And also, im running stock FPR, so may it be benificial to fit the adjustable one I have to accompny the new fuel pump?

Today I have taken off the air filter, not dirty or blocked in any way, cleaned the Coolant Temp plug and socket, removed and cleaned the Idle Control Valve, which incidently had a bolt missing (!??!), checked the MAP sensor and that was fine, NOT checked the lambda though.

Failing all of that fails again, could i swap my Watanabe ECU for the standard one I have, would that help? I hope its not the fuel pump cos I launched the OEM one, but as I said I only have the standard FPR, so regardless of how much fuel is pumped to it, I thought that the FPR would still be "stock" pressure?

Thanks again for you knowledge guys, means alot!
 
weeJohn

weeJohn

Lifer
I got a few through MOT with an uprated pump and PNP ECU, worth trying it with the stock ECU to see if that sorts it.
 
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