Hi

can anyone help.

Had my MOT recently with no issues apart from high emissions on tick over.

The guy said it’s supposed to be 0.2 and it was up in the 6-7 range.

On reving the car they did come down considerably but as soon as it went back to tick over it went straight back up to 6-7.

Everything is standard apart from a map and stainless exhaust.

Any advice would be appreciated 

thanks

@goa200d What are the actual emissions figures, not just the numbers?

Sorry I don’t have any specific figures as he did manage to get it to pass.

52 minutes ago, goa200d said:

Sorry I don’t have any specific figures as he did manage to get it to pass.

Good enough for now then. Before next year's MoT, maybe on a dry day in September? give it a good ragging for maybe 10 minutes on a road where you'll spend a lot of time accelerating or braking, then let it idle for a minute before switching off.

Good advice for a general emissions failure at all revs but unlikely to help with the tickover emissions problem, I would suspect either the remap, the EGR valve or whatever valve or flap that engine has fitted to stop the engine over-running on shut down, I should know what it is having owned the same vehicle & engine & having declagged all these components but the detail has gone from my memory.

1 hour ago, J.R. said:

whatever valve or flap that engine has fitted to stop the engine over-running on shut down

It's usually called an "anti-diesel valve".

Thanks, I had brain fade.

This is a petrol engine, isn't it?

Must be something very wrong to be putting out 6-7% CO at idle. 

Never be in an enclosed space with engine running before that's sorted.

 

Oops, I must have misread Kens post and decided that the OP had a 110TDi MK1 Octavia.

Yes sorry petrol 1.8t vrs

I would start by getting the voltages read on your precat lambda sensor at idle, over 6% more than specified CO at idle says you have a fair little problem looming there. Did he mean 0.60% - 0.70%, or was it actually 6.0% - 7.0%?

 

It would also be worth a code scan too.

 

Is the exhaust system clear of any blows or leakage?, also, did you get an emissions test sheet with your mot test?

 

I would also check your wiring at the maf is sound.

 

I bet it smells a bit when it ticks over I'm guessing?.

 

As Wino said, don't work with the engine running in an unvented garage with those readings, as it won't end well for you.

 

Hope it helps,

 

Phil.

Edited 15 November, 20214 yr by kentphil1

It was 6.0%-7, extremely high. But only at tick over.

The exhaust was blowing but I fixed that prior to the mot so it’s not that.

I’ll have to get those sensors tested.

It sounds like I’m going to have a nightmare solving this issue 

 

2 hours ago, goa200d said:

It sounds like I’m going to have a nightmare solving this issue

Checks - When were air filter and oil filter last changed? When were spark plugs and oil last changed?

 

If they're all good, check fault codes, and suspect a lambda sensor fault.

I do oil and filter myself every year.

could probably do with a new air filter I’ll replace it.

I did spark plugs a few years ago.

 

 

7 minutes ago, goa200d said:

could probably do with a new air filter I’ll replace it.

 

Replace your air filter annually or correct to a high annual mileage etc. I left mine (as it was alright when changed the oil and oil filter) and got to the end of summer and the car was running like it was in limp mode because of how bad the filter had gotten. Swapped the air filter for a brand new panel one and the power increase was staggering because of how bad the old one was.

Edited 16 November, 20214 yr by AnnoyingPentium

48 minutes ago, goa200d said:

did spark plugs a few years ago.

And what sort of mileage? We're chasing an emissions fault, which is most likely airflow, lambda, sparks or dribbly injectors. So I'm working the issue from ease of checking first.

2002 petrol vrs 107k miles

 

Mate had a fail on his Passat 1.8 turbo and it was the cat which needed replacing. His mileage was 113k. His was 2001 reg

Edited 16 November, 20214 yr by edbostan

52 minutes ago, goa200d said:

2002 petrol vrs 107k miles

 

If you're answering the question I asked "What mileage have the current spark plugs done?" then I'm surprised you didn't get this issue years ago.

Oh god no, my mistake. The car is on 107k not the plugs

No idea how many miles the plugs have done. Would this make much of an issue?

The car runs fine so I presumed they would be ok

1 hour ago, edbostan said:

Mate had a fail on his Passat 1.8 turbo and it was the cat which needed replacing. His mileage was 113k. His was 2001 reg

I’ll have to consider the cat then thanks for the heads up

7 hours ago, goa200d said:

The car runs fine so I presumed they would be ok

Well, IME old plugs don't run as well as new ones. Ever.

9 minutes ago, KenONeill said:

Well, IME old plugs don't run as well as new ones. Ever.

 

My Grandad's old Punto was living proof of that.

I see you mention a stainless exhaust in your original post, was it a full exhaust and de-cat, or just cat back?

It’s just a cat back

8 hours ago, kentphil1 said:

I see you mention a stainless exhaust in your original post, was it a full exhaust and de-cat, or just cat back?

Just a cat back buddy