Hi all,

I'm having trouble getting my 6N1 1.0L Polo through ithe MOT test! It has done about 125k miles.

It has failed on me twice now, both times on emissions.

First time round my catalityc converter seemed to be broken down, it was an old one it had on it when I bought it a year ago. The readings that time round were as follows:

Engine oil temperature: 83 Deg C

Fast Idle Test: FAILED

Engine Speed: 2450-2850 rpm MANUAL CHECK Pass

CO: 0.614% % Fail

HC: 459 ppm Fail

lambda: 1.112 Fail

Second Fast Idle Test: FAILED

Engine Speed: 2450-2850 rpm MANUAL CHECK Pass

CO: 0.687% Fail

HC: 565 ppm Fail

lambda: 1.113 Fail

Natural Idle Test:

Engine Speed: 550-850 Pass

CO: 0.496% Pass

When I took it for the retest after fitting a new catalytic converter on the readings were actually worse!

Engine oil temperature: 62 Deg C

Fast Idle Test: FAILED

Engine Speed: 2450-2850 rpm MANUAL CHECK Pass

CO: 0.800% Fail

HC: 823 ppm Fail

lambda: 1.213 Fail

Second Fast Idle Test: FAILED

Engine Speed: 2450-2850 rpm MANUAL CHECK Pass

CO: 0.869% Fail

HC: 477 ppm Fail

lambda: 1.106 Fail

Natural Idle Test:

Engine Speed: 550-850 Pass

CO: 0.489% Pass

The guy at the MOT Centre said it seemed to have a slight misfire and that it was burning some oil. About a month ago, before both tests, my Polo had a serious misfire.

I found one of the spark leads had gone so I replaced the spark plugs and leads with new ones, this seemed to solve the problem. At the time, I noticed the crankcase breather was full of oily sludge and it had made its way into the air box. I cleaned the box replaced the air filter.

Over the weekend I got under the car and check for any exhaust leaks, made sure the new cat was attached correctly to the rest of the exhaust system, I reinspected the airbox and found no sludge in the crankcase breather. I also gave the car a good old italian tune up as well, just in case.

I find the trouble with the emissions failure is that solving it seems to involve a lot of fault hunting! My next course of action is a change of oil to a slightly thicker gradient and new oil and fuel filters as it could be the case that the oil is making its way past the piston rings...

What are your thoughts on this? Really hope I get to the bottom of this one!

Cheers guys!

Melo

Edited 25 November, 201312 yr by Melo

It might pay to carry out a compression test, or at least have a look at the electrode end of the new spark plugs and see what condition they are in - keep the plugs in order, so that if there are any differences in colour or contamination, you will be able to identify the cylinder that is causing the problem.

It may also pay to buy a tin of carb cleaner (Halfords) and give the throttle body a spring clean.

Regards

engine oil temps look a bit low...try and make sure its tested when piping hot

Edited 25 November, 201312 yr by steveo3002

It might pay to carry out a compression test, or at least have a look at the electrode end of the new spark plugs and see what condition they are in - keep the plugs in order, so that if there are any differences in colour or contamination, you will be able to identify the cylinder that is causing the problem.

It may also pay to buy a tin of carb cleaner (Halfords) and give the throttle body a spring clean.

Regards

Cheers caretakerplus,

,

I'll check them this evening and post an update, the previous set of spark plugs I changed were worn! Fingers crossed these aren't oil fouled!

engine oil temps look a bit low...try and make sure its tested when piping how

Yeah, steveo3002, next time her I'll make sure she's pipping hot!

Cheers!

As above really but also make sure your coolant temp sensor is good and has it had a recent oil change, some times the oil can become heavily petrolated and this can have an effect on emissions.

Well guys, I've got an update on my Polo...

Changed they oil on her, checked the compression, checked spark plugs and leads... Took it in for the retest yesterday and it failed.

This time the CO readings were 1.200%! I was told it is the engine and the work to have it done would cost around £400.
Don't know what to do, my only question is whether the lambda sensor could have an effect on oil burning.

Does it run ok otherwise?

Try some fuel system cleaner?

Give it a good blast around.

I'd say an oxygen sensor is to blame if the rest is fine.

I'd try a new lambda sensor and before the test give it a proper thrash.

Cats work best when they are hot.

Also I'd like to know what 'engine' work they are going to carry out to justify £400?

Lambda sensor seems like it maybe paying a part of this.

Have you checked the ignition timing?

Does it run ok otherwise?

Try some fuel system cleaner?

Give it a good blast around.

I'd say an oxygen sensor is to blame if the rest is fine.

It runs ok otherwise! Used some redex before the first test!

I'd try a new lambda sensor and before the test give it a proper thrash.

Cats work best when they are hot.

Also I'd like to know what 'engine' work they are going to carry out to justify £400?

Anti-freeze: £17.50

Cambelt kit: £41.71

Head set: £65.32

Head bolt: £14.81

Skim: £50.00

Labour: £160.00

Subtotal: £349.34

Vat: £69.86

Total: £419.20

Water pump: £37.96

That's what they've quoted me :/

Was wondering if it were the seals is Wynn's Engine stop leak

Lambda sensor seems like it maybe paying a part of this.

Have you checked the ignition timing?

If there were an oil leak, would that in turn affect the lambda sensor? What I find strange is that she doesn't show blue smoke when I'm driving around. It's only when she's at 4000 rpm! I've also given her an italian tuneup...

By the way, I appreciate your advice guys!

.

Edited 5 December, 201312 yr by Melo

how much oil does it use over say 1000 miles

maybe worth seeing if theres any local recomended mechanics that can give an honest opinon

* i think* the co is unbured fuel? more likley a cat /o2 sensor problem