Has any owners of cars with the DPF filter removed had any issues with emissions during their MOT. Mine has just failed it's MOt due to high emmisions. I didn't think this would be an issue to be honest. Further to that, i've been having a few probs with the light for the DPF filter coming on for a bit then going off. This happened before and was diagnosed as a faulty lambda sensor. I'm thinking there might be either a dodgy sensor fitted or a loose connection to it. My question is, when the car had it's MOT done the light may have been on (not sure as my partner took it to get tested, but was certainly on when she picked the car up) can the dodgy sensor cause the settings for the fuel system to be messed up causing an increase in emmisions?

thanks,

Fitz.

Simple answer-yes. If the lambda sensor is faulty, then the engine could be under or over fuelling causing an emissions failure. If over fuelling then you could have high CO and HC's, if under fuelling then you could have high NOx.

Thanks for the quick reply. I hope it's only this but i'm slightly sceptical of having a duff lambda sensor replaced by a brand new duff one. I know it can happen though.

Sorry, just re-read and realised your TDI. Did you have your main cat removed too? It sits in the same housing as the DPF (before the actual dpf).

It's not that uncommon for new lambda sensors to be faulty or just not run right when fitted the car. NGK do a range of sensors that have oe plugs on them. Keep away from the ones on flee bay, had many friends gone down that route to save money, and all were faulty in differen ways each.

It's a TDI.

Did it fail the smoke test?

If so what was the reading?

It's a TDI.

Did it fail the smoke test?

If so what was the reading?

Not sure which test it failed. I'm out of the country at the min but my not very technical girlfriend just said it had failed the emmisions test. She said the tester said try some fuel system cleaner.

The lambda sensor was hopefully a pucka one as it was nearly 100 quid.

Not sure if the CAT was removed, i'll have to ask Jabba about that one.

Would it make a difference as to what test it failed on?

Cheers.

Diesel emissions themselves are not tested, the car is only subject to a smoke test. Poor remapping can cause the car to fail an mot in the case of a diesel.

Currently a properly mapped diesel can pass the MOT with no CAT or DPF fitted.

The Lamda sensors could also cause issues.

I think I recall seeing something similar on another thread, but I can't find it at the minute. A lot of diesel owners recommend giving the car a right good thrashing before the MOT test (I think we like to call it an Italian tune up). This generally results in lots and lots of smoke and clears the system out enough to then pass the 'smoke test'. Might be a cheap fix ???

I think I recall seeing something similar on another thread, but I can't find it at the minute. A lot of diesel owners recommend giving the car a right good thrashing before the MOT test (I think we like to call it an Italian tune up). This generally results in lots and lots of smoke and clears the system out enough to then pass the 'smoke test'. Might be a cheap fix ???

Thats what I'm thinking. Can't see it being a poor MAP on my car as Jabbasport were the ones to carry out the re-map. The missus drives quite slow and every time I get in it I get the usual smoke cloud when it's booted. Trouble is i'm only home 3 times a year for a few weeks so convincing Gem to give it some beans might be difficult.

Fitz.

Managed to get the fail figures from the certificate.

It failed the smoke test which has a limit of 3 1/M

test one value of 5.36

test two value of 5.92

test three value of 5.87

test four value of 4.91

test five value of 4.71

test six value of 4.3

Zero drift 0.02 1/M

Mean value was 4.62.

No idea what any of that actually means except 4.62 is above the limit of 3

A properly tuned car won't smoke. Speak to Jabbasport as it's unlike them to provide poor mapping. Alternatively we have an MOT testing station next door and can do a back to back test with our map if you'd like?

It certainly looks like your car is in need of a good italian tune up. The smoke figures are dropping as the test goes on indicating the system is cleaning itself out.

I usually take my car on a long uphill stretch just after filling the fuel tank, when the car is at it's heaviest and put my foot to the floor in 2nd, 3rd and maybe 4th until it stops accelerating. It won't do the car any harm. Have you anyone who will give your car a good hard run and then drive it to the MOT station?

Ian

I'm in Lincolnshire and so is Brimma if you need a local member to take the car for a short clear out, we both drive mk2 Octavia vRS's also

Talking about giving cars some beans before the MOT, i noticed my diesel vrs wont rev above 3000rpm when it's stationary.

Talking about giving cars some beans before the MOT, i noticed my diesel vrs wont rev above 3000rpm when it's stationary.

Mine is the same, but seem to remember it only holds at 3000rpm if the car is stationary, in gear with the clutch in.

thanks for the offers of taking the car for a clean out but i've been assured by Gem that she understands what needs to be done to clear it out. For some reason she is hell bent on trying to squeeze as much MPG out of it as possible so she constantly short shifts and keeps the rpms as low as poss. She has far more restraint than me.

Luckily we did not get charged for the MOT so the tester said just nip in some time next week to have it tested again.

Thanks for all the helpful info guys.

Fitz.

Talking about giving cars some beans before the MOT, i noticed my diesel vrs wont rev above 3000rpm when it's stationary.

This seems to be a designed-in software characteristic of the new cars. A lot of Yeti owners are reporting the same phenomenon with their cars.

Ian

A properly tuned car won't smoke. Speak to Jabbasport as it's unlike them to provide poor mapping. Alternatively we have an MOT testing station next door and can do a back to back test with our map if you'd like?

Ben,

It only has a quick cloud of smoke after it's been booted. This happens very rarely and like I mentioned before, it's only when I get back off leave and drive back from the airport. Do you think this should not happen?

Fitz.

Ben,

It only has a quick cloud of smoke after it's been booted. This happens very rarely and like I mentioned before, it's only when I get back off leave and drive back from the airport. Do you think this should not happen?

Fitz.

Visually when driving perhaps that's the case, however it seems the MOT test shows a different result. The MOT test is only for smoke and in that respect it shouldn't be any worse than a standard car, DPF removed or not.

I thought the whole point of the DPF was to remove the smoke?

I understand the reasons / needs to remove them but surely a side effect of DPF removal is increased smoke output?

I certainly agree with giving the car some beans on the way to the test station, giving the engine and exhaust a good clean out for the emissions test...

This seems to be a designed-in software characteristic of the new cars. A lot of Yeti owners are reporting the same phenomenon with their cars.

Ian

My DSG equipped CR140 Yeti will only rev to 2500, much to the annoyance of the noise testers at Castle Coombe.

I thought the whole point of the DPF was to remove the smoke?

I understand the reasons / needs to remove them but surely a side effect of DPF removal is increased smoke output?

Well, yes, but that doesn't mean it's allowed to smoke like a chimney without one.

For some reason she is hell bent on trying to squeeze as much MPG out of it as possible so she constantly short shifts and keeps the rpms as low as poss.

Not a good way of driving for the longevity of the engine.

This will be putting extra strain on your DMF and also because your turbo will not be getting a work out you run the risk of the vanes sticking as well.

Best sticking around 1800-2200 rpm which is bang on where the power is, so you only need light throttle to keep moving.

If you are driving everywhere at 1500 rpm you are putting undue strain on components, just as bad as over revving. This is why when running in a new engine manufacturers tell you that laboring the engine does just as much damage as revving highly.

Hi John,

We can investigate this when the car comes down for service if you'd like, even pop it into our local station to test it. As you say, it could just be Gems driving, but don't let her know i said that..

Cheers

Kev

Kev,

Don't worry mate, i'll not tell Gem that lol.

The car is being tested next sat at the same place so if it still fails i'll get your local tester to take a look.

PS. Did you get my email ref poly console bushes and poly anti roll bar bushes?

Fitz.