MOT failure on emissions

[DanM]

Took my car for an Mot on Tuesday passed everything fine apart from the emissions

It passed the CO levels but failed on the lambda test - I believe it has to be within 0.97-1.03. My result was a 1.06

The car had been sat for a week and my dad had to drive it a mile to the mot station as I was away. Would this have made a difference I had been told a few times to give the car a good thrash before taking it for an MOT?

Its got a plm header, sports cat and custom exhaust, skunk2 intake and tegiwa induction all mapped with Hondata only 2 months ago.

Any ideas where the problem could be - dodgy lambda sensor itself? Or would something like cataclean work?

 

[Dan Evans]

After a 10 mile drive on a warm morning to the MOT station, mine failed on emissions, it was well over. The tester left the car running throughout the test saying it would need heating up still, passed no trouble at the end of the test.

Get it hot and take it in again? Or drop in to any MOT station and they should check emissions cheaply while you wait. I had mine checked on a previous car for £5.

 

[Erm]

the tester is an arse then.... Go for a 20 minute drive before the retest let it all heat up and run nicely on idle, get high up in the rev range too.

It'll then pass no problem.

 

[DanM]

Thanks

I will give it a good drive then before I take it back for the retest and tell them it might need to be warmed up properly. Good idea to get it checked elsewhere first cheaply to avoid another MOT charge if it does fail again.

 

[Erm]

Thanks

I will give it a good drive then before I take it back for the retest and tell them it might need to be warmed up properly. Good idea to get it checked elsewhere first cheaply to avoid another MOT charge if it does fail again.

Surely they offer a free retest?

If not get yourself a new MOT place

 

[DanM]

Took the car back again and its failed again giving the same results. Could there be something wrong with the sports cat or the lambda? Or are those results probably about right?

 

[Benneh]

Just checked my results from the MOT in May and it came back at 1.013 on the Lambda, was 1.002 the year before that. Could be a possibility that the Lambda is on the way out, but at the say time cats don't last forever...

 

[DanM]

Thanks Benneh

The cat is new as of 4 months ago (200 thing) - I ran it for 6 weeks before I got the car mapped at TDI. Will have a look at Lambda prices. Any chance I burnt the CAT out in those first 6 weeks?

Really annoying as the car runs fantastic!

 

[Benneh]

I'd say it's very unlikely to be the cat then unless something is seriously wrong with it!

Any change in fuel recently or anything? Just trying to think of possibilities to rule out!

What were the CO, HC and engine temp readings like?

 

[DanM]

Everything was spot on apart from the lambda reading.

I only ever used Shell V power in the 6k I have had the car. If the sensor is on its way out that's fine I don't mind fitting a new one, but I don't want to waste money if that is not the cause!

 

[Benneh]

Only other thing I can really think of then is an air leak in the system somewhere. Did you put the new cat on yourself? There's a possibility that it isn't mated / seated perfectly so some air is escaping. If the cat is sat fine then anywhere upstream of that, so exhaust manifold, could have a leak / small hole somewhere. Not the easiest thing to check unless you can get it up on a ramp though!

 

[DanM]

The CAT was put on part of system. I put down 251bhp with the sports cat so doubt its leaking

 

[Benneh]

Well if you're adamant that everything is mated correctly and there are no holes or cracks in any of the exhaust system, then the problem gets much more complicated and the fuelling isn't correct which could just be down to an O2 sensor, resulting in a lean A/F mix, or it could be worse.

Personally I think you've got an air leak somewhere.

 

[DanM]

Ok thanks - I will take another look and see if I have an air leak somewhere. Certainly got some stuff to go and look at that. cheers

 

[Rom]

What are the exact readings. All of them, not just lambda.

Your running lean if your lambda is high. But the hc, co, co2 and o2 readings will tell us more.

You running k100 or kpro?

 

[DanM]

I am running Kpro

Here were my results...

Fast Idle Test - Fail
Engine Speed - Not Checked
CO Level - 0.00% max 0.30
HC Level - 17ppm max 200
Lambda - 1.06 0.97 - 1.03

 

[CaLi]

perhaps a leak on the exhaust system?

 

[Erm]

Did the tester raise the revs at all? Or did he leave it to idle?