MOT emissions fail help

[danjama]

What could this .3% be people?

I had a suspicion during the test that the tester was over-revving it so was annoyed to see the engine speed reading missing. Is that allowed?

It's my first MOT so not sure.

The readout suggests over-fuelling which would align with poor-ish fuel consumption. But I'm wondering where to start to be honest.

Please help!

She recently had new plugs and oil/filters too.

[RikH77]

Carbon Monoxide reading, and it scraped it on idle

[Willenium]

Could try a fuel additive and giving it a good rag before taking it back in?

[Rob66]

Hi Dan

Just had mine tested this week and mine doesn't show Engine speed either, just not checked like yours. Although your tester is literally just down the road to me i haven't used them in the past.

My emissions were way higher than yours and i ended up changing the Water Temp Sensor, then the CAT and finally the Oxygen Sensor to get it down to below the limit and pass.

Good luck with it, Peter from SBITs is worth a call for advice.

Rob

[2tmike]

If the guy was really revving it he was probably trying to help you get a pass !!!
The HC is well in so it's unlikely to be a cat problem and as you said it looks like slight overfuelling. On retest a fuel additive plus a really hot engine might get you through but there's no way to tell. Also check the airfilter. Otherwise it might be the lambda sensor or temp sensors ?

[danjama]

Thanks everyone.

I really don't want to change loads of expensive bits to solve the problem.

I recently went from stock airbox to k&n induction kit but people say this should still get you through no problem.

I have since reset the ecu by disconnecting the battery for a bit as someone said this might reset the air/fuel values in line with the new filter type?

The car is going back in on Monday, so might go and grab a fuel additive as has been suggested.

I don't think the problem was the engine/cat temps as I was ragging it around the B186 for about an hour before hand.

If it fails again, i think my first step will be the lambda. Does that seem right? Or would it be better to change water temp sensor? Where would i find the water temp sensor on the thermostat? Might be able to check the condition?

It's really crazy how low the tolerances are on the emissions test.

[danjama]

Hi Dan

Just had mine tested this week and mine doesn't show Engine speed either, just not checked like yours. Although your tester is literally just down the road to me i haven't used them in the past.

My emissions were way higher than yours and i ended up changing the Water Temp Sensor, then the CAT and finally the Oxygen Sensor to get it down to below the limit and pass.

Good luck with it, Peter from SBITs is worth a call for advice.

Rob

Brutal amount of work there to get it passed

Where did you take yours?

[burtosa]

just one quick point to try had my car in for mot today passed but queried
proceedure tested left hand exhaust when viewed from back he said would have failed on that one
he then put probe in right hand exhaust much lower figures passed?
strange but true perhaps worth a mention
try it and see unexplained fact

[Rob66]

Hi burtosa

Thats interesting i 'think' they are meant to place a sensor in each pipe.

Hi Dan

Yes it was flipping expensive - had it done at Mr T as they owned me a tank of fuel from a previous 'willy up' they made, so while i was there got them to do it, They said i needed a new full exhaust (no way the Mongoose back box is only 2 months old and like new) but i was aware that my Cat was not the best so picked up one from CATMAN (1/3 price of OE), (good service by the way).

Before i had it fitted i spoke to Peter G at SBIT who suggested a Water Temp Fault, so i changed that first. That dropped the emissions but not by enough, so on when the CAT, down but still not by enough, so last chance changed the Oxygen Sensor and way down and PASS.

I have a feeling if i had changed that first i would have passed then but hey ho live and learn, no more Mr T for me. The overall cost was embarrassing

Good luck with yours mate. The Oxygen Sensor by the way is made by Denso for Toyota but from Denso they are 1/3 of price.

[danjama]

Thanks Rob, very helpful