1st MOT failed...

Chris · March 15, 2006, 09:58

Had a rather disturbing call from the dealer last night that my '2 had failed it's 1st mot - co2 emissions too high apparently!!

I can only think of three possible causes in my case, as i don't have any other engine mods:

1) unichip
2) damaged o2 sensors when removed for heatshield painting
3) h+s inlet elbow

I reckon the unichip is most likely - anyone else had problems? I've still got my precats by the way, so i was a little surprised that it failed...

spit · March 15, 2006, 10:59

I'd go for O2s as the prime suspect

I'm no expert (get the disclaimer in early and please s:flame: :flame: s:flame: if I'm talking bunkum!) but here's my logic on this....

Under MOT test conditions, the car's ECU should be self-regulating fuel using feedback from only the O2s. So, even if your MAF is grubby and you've changed the intake, the O2s should feedback any mix problem and the ECU will adjust.

.......or the garage probe is grubby and poorly calibrated - not unheard of.

I'd clean the sensors, reset the ECU, go for a good punt and try again. & when it passes get those precats out s:wink: :wink: s:wink:

I've heard suggestion that mapping timing adjustment can play a part but I still haven't got my head around how the extent of the burn isn't picked up and adjusted through the O2 feedback to ECU s:oops: :oops: s:oops: Perhaps others can elaborate.

Ernie Ball · March 15, 2006, 11:04

Just out of curiosity, why wouldn't you take the unichip out as a precautionary measure prior to the MOT?

Chris · March 15, 2006, 11:55

yeah thinking about it now, i probably should've of done ernie, but i just didn't think of it at the time...

Chris · March 16, 2006, 11:41

well, that was an expensive mistake!!!

it turned out to be the unichip, and the nice dealer charged me 140 quid for investigation and removal!! s:evil: :evil: s:evil: s:evil: :evil: s:evil:

Note to self - take out unichip before next years mot...

spit · March 16, 2006, 11:47

Quote from: "Chris"it turned out to be the unichip

Quote from: "spit"I'd go for O2s as the prime suspect ..... I'm no expert ....

but keen to learn s:P

s:P

So, what is it about unichip mapping that upsets the MOT emissions test? Does the unichip over-ride the ECU's closed loop regulation? Confoosed s:shock: :shock: s:shock:

Chris · March 16, 2006, 12:01

no idea, all i know is that it failed the first fast idle test at 0.49% vol and then failed the second test also, but at the lower level of 0.25% vol.

The pass mark is 0.20% vol and the test is done at 2500-3000rpm. When it was repeated running on the stock ecu, it easily passed at 0.02% vol s:shock: :shock: s:shock: At least it proves that the o2 sensors and cats are working ok i guess... s:roll: :roll: s:roll:

roger · March 16, 2006, 12:04

Quote from: "spit"So, what is it about unichip mapping that upsets the MOT emissions test? Does the unichip over-ride the ECU's closed loop regulation? Confoosed s:shock: :shock: s:shock:

Interested to know if this is possible. Don't think anybody else has had this problem though!

AFAIAA the Unichip (well those mapped by Millways, any way) only come into play on full throttle. I doubt if this is the case on the MOT, probably run at 3 - 4K.

Any ideas?

<edit> Just read Chris' reply. Can't see how the Unichip can induce a ten-fold increase in CO2 emmissions, unless its programming is totally up the chute! Come to think of it, Millways had a probe stuck up the exhaust when they were mapping, presumably they were checking thisa sort of thing out</edit>

Two's Company · March 16, 2006, 12:39

Quote from: "roger"AFAIAA the Unichip (well those mapped by Millways, any way) only come into play on full throttle. I doubt if this is the case on the MOT, probably run at 3 - 4K.

Any ideas?

As I understand it the dyno run is done at full throttle but the fueling and timing are still adjusted at different RPMs. When Hedley mapped mine he said that he was seeing up to 14 BHP increases at certain points in the range. He said that mapping it at different throttle positions takes too much time and the benefits aren't worth it.

Chris · March 16, 2006, 14:58

Quote from: "roger"unless its programming is totally up the chute!

That's my suspicion, as mine is one of the pre-mapped us spec ones..

looks like i'm gonna be better off getting it remapped over here on the car anyway, like everyone said at the time of the GB.. s:roll: :roll: s:roll: oh well, live and learn...

Anonymous · March 16, 2006, 19:08

Mine passed on emmisions with UC fitted & tuned by Millway

heathstimpson · March 17, 2006, 19:59

I have my first MOT at the end of the month. Looks like I'm going to have to removed the ICE to get to the Unichip to remove it before I go as I'm running the American map at the mo; a real pain in the backside. Shame it can't be switched out s:? :? s:?

Chris · March 18, 2006, 00:28

if it wasn't such a pita, it would interesting to leave it in and see if yours fails as well.. I was even running on the less aggressive map a..

spit · March 18, 2006, 00:37

Quote from: "Chris"if it wasn't such a pita, it would interesting to leave it in and see if yours fails as well.. I was even running on the less aggressive map a..

It would be good to have some feedback, but if the MOT station is on the new networked system it'll cost you for a re-test s:cry: :cry: s:cry:

If its a friendly garage though, why not pop down for a free probing before your test date Heath?

heathstimpson · March 18, 2006, 06:06

Quote from: "spit"
Quote from: "Chris"if it wasn't such a pita, it would interesting to leave it in and see if yours fails as well.. I was even running on the less aggressive map a..
It would be good to have some feedback, but if the MOT station is on the new networked system it'll cost you for a re-test s:cry: :cry: s:cry:

If its a friendly garage though, why not pop down for a free probing before your test date Heath?

It's booked with the service at Toyota unfortunately s:? :? s:?

Anonymous · March 18, 2006, 07:32

Quote from: "Chris"
Quote from: "roger"unless its programming is totally up the chute!

That's my suspicion, as mine is one of the pre-mapped us spec ones..

looks like i'm gonna be better off getting it remapped over here on the car anyway, like everyone said at the time of the GB.. s:roll: :roll: s:roll: oh well, live and learn...

Interesting. If you've got a US spec Dastek tune then its possible its the one off my car. That map was tuned to come on anytime the load was deemed sufficient to enable open-loop. Something like at the 150th out of 233rd throttle position. This could be as low as 2500 rpm under certain conditions. Of course, it would not alway be in open-loop and so a bit of a fight between the OEM and Dastek ECU would ensue. Not that the driver could notice these conflicts but its most likely the reason for the MOT failures.

Is 2500rpm a range where the MOT testing takes place?

Anyhow, the final tune raised the power 3-5% throughout the RPM band not just at WOT. I know this is so because I had it tuned both ways and could feel the difference. Originally the unichip went active only at WOT. Years later iI had it tuned much more extensively. It took ~80 dyno pulls over a 3 week period before Unichip USA copied the map off and used my setup as the final test fit of their PnP harnesses before shipping them to S.A. for duplication and distribution.

Anonymous · March 18, 2006, 22:18

Lo all,

Just joined ur club..........impressive webby!

Love my mk3 '2 (Chose it over elise as much better package all round......i.e. couldn't walk after 20 min test drive!!!) she just needs a bit more umph.....dont want to turbo her or drop the 190 and reckon from reviewing all the posts on the subject that the unichip is the way forward (Maybe with an induction kit).

Got a few more questions.......(sorry!! s:lol: :lol: s:lol: )

Setting up for two settings: Normal 95ron and GoGo juice 97 - good idea?

Can anyone recommend a tuner/supplier near s. wales?

Any further info out there esp bout new system from US?

Thoughts?

Cheers s:)

s:)

kanujunkie · March 19, 2006, 08:15

Quote from: "Jonotaff"Lo all,

Just joined your club..........impressive webby!

Love my mk3 '2 (Chose it over elise as much better package all round......i.e. couldn't walk after 20 min test drive!!!) she just needs a bit more umph.....dont want to turbo her or drop the 190 and reckon from reviewing all the posts on the subject that the unichip is the way forward (Maybe with an induction kit).

Got a few more questions.......(sorry!! s:lol: :lol: s:lol: )

Setting up for two settings: Normal 95ron and GoGo juice 97 - good idea?

Can anyone recommend a tuner/supplier near s. wales?

Any further info out there esp about new system from US?

Thoughts?

Cheers s:) s:)

i've replyed to this on your other thread, please keep on track

Chris · March 19, 2006, 13:33

Quote from: "wts"Is 2500rpm a range where the MOT testing takes place?

Yep, it sure is - between 2500-3000rpm according to the failure report..
WTS - Did you have any other mods on the car when they took the map?