Failed MOT: Emissions - Unichip?

Sam · February 21, 2004, 15:56

Hi all,

3 Years have zoomed past and I put my car in for an MOT today and it failed due to excessive CO emissions.
Its going back into the dealer on Monday to fix, but I am just wondering could the Unichip I have fitted cause this?
I am guessing that because it adjusts fuelling/air timings and mixture it could?

I just want to check because I dont want to get a bill on Monday when they say it isnt going to come under warranty. If it could be I could remove the Unichip before then.

Just seems a bit strange as I only had all 3 cats changed about a month ago at the dealer.

Any advice appreciated. Thanks.

aaronjb · February 21, 2004, 16:39

What caused you to have the CATs replaced?

If it was oil contamination causing their breakdown, did the dealer replace the O2 sensors at the same time? If not, it's highly likely that the O2's are contaminated and not reading properly - hence the rich running..

If properly mapped, I'd think it's unlikely that the Unichip would be set to run particularily rich at idle - there's no benefit to it AFAIK.

Aaron

Anonymous · February 22, 2004, 10:37

Well i'm having the same problem, so please keep us informed of your results.

I'm going with a highly contaminated O2 or/and MAF being a problem as even with your unichip, firstly the installer/tuner wouldn't alter a map for idle and secondly even if they did the car is running closed loop at idle so the unichip is not doing anything.

Sam · February 22, 2004, 13:10

Quote from: "aaronjb"What caused you to have the CATs replaced?
Aaron

Well I never really got to the bottom of that - the dealer was blaming the HKS induction kit, and for a while I did suspect that the intake may have sucked up some metal shavings, but in the end I was just leaning towards the 'standard mr2 cat failure problem'.

Quote from: "mr-s_turbo"I'm going with a highly contaminated O2 or/and MAF being a problem as even with your unichip, firstly the installer/tuner wouldn't alter a map for idle and secondly even if they did the car is running closed loop at idle so the unichip is not doing anything.

True I didnt think of that - the map only kicks in at a few thousand rpm.
Accoring to the paperwork I received from the warranty work on the CATs they didnt replace the O2 sensor - so maybe its contaminated with oil and causing the problems.

Its going in tomorrow so I'll keep you posted.

Anonymous · February 22, 2004, 13:21

Well i've just pulled my O2 sensor and it was really black and sooty. Gave it a good clean, now that's got to cause some problem with readings.

Let us know anyway Sam because there seems to be a few crop up recently with this problem.

Ian

Sam · February 23, 2004, 15:43

Just got off the phone to the dealer - O2 sensor on order.
Should be delivered and installed tomorrow - I'll get the full run down when I go into the garage then.

You'd have thought they would have changed or at least checked that when they replaced the CATs wouldn't you? s:? :? s:?

Anonymous · February 23, 2004, 16:14

Is this under warranty? If so then fair enough new is good s:D

s:D but if your paying for it i'd want them to clean it and check if that cures it first.

I'm going to have my emissions re-checked again tomorrow after cleaning my O2 sensor. If it fails i'll take out fuel with my e-manage cause i've had enough messing about just for a MOT. s:roll: :roll: s:roll:

mph · February 23, 2004, 16:46

I'll be popping by Millway on Thursday, I'll check on emission levels then.

Anonymous · February 23, 2004, 16:52

s8)

s8) I was about to shout out to you to see if you've had any problems, as we've been turbo'd nearly same amount of time. Can't remember what you've done with your cat? still on, or straight through? or even high flow one?

Sam · February 23, 2004, 18:20

Quote from: "mr-s_turbo"Is this under warranty? If so then fair enough new is good s:D s:D but if your paying for it i'd want them to clean it and check if that cures it first.

Yeah the standard warranty is up at the end of the month, and due to my recent problems (belt tensioner, gearbox, and cats) I took out an extended warranty anyway for a further 2 years. So I'll happily settle for new s:wink: :wink: s:wink:

Hopefully that'll sort it - just got to mess about putting reg plates on now as mine aren't standard and that was the second thing they failed the MOT on!

mph · February 23, 2004, 23:07

Quote from: "mr-s_turbo" I was about to shout out to you to see if you've had any problems, as we've been turbo'd nearly same amount of time. Can't remember what you've done with your cat? still on, or straight through? or even high flow one?

What's a CAT? /innocent

The custom exhaust place was v unhappy with the PE downpipe (way to restrictive in their opinion), so the exhaust goes all the way back to the turbo. Has caused a few headaches to allow it to have sufficient flex as the engine moves but seems ok now. It might not look anything special from the outside, but it's 2 1/2" core all the way back with a straight through silencer so efficient and light.

Anonymous · February 24, 2004, 19:12

Sam you had any news on yours yet? Couldn't make it today to test mine s:x :x s:x

Sam · February 24, 2004, 20:03

Quote from: "mr-s_turbo"Sam you had any news on yours yet? Couldn't make it today to test mine s:x :x s:x

O2 sensor replaced today - going back in for the test tomorrow - been faffing about with reg plates today s:roll: :roll: s:roll:

Will get the emissions specs before and after tomorrow if I can and confirm if the O2 sensor was contaminated.

Anonymous · February 24, 2004, 20:07

s:x :x s:x OK i'll wait till tomorrow to see if it's that.

What's up with your plates then to fail?

Sam · February 25, 2004, 10:19

Non-standard font size (personalisied plate) and its a sticker plate on the front.

Sam · February 25, 2004, 17:25

Quote from: "mr-s_turbo":x OK i'll wait till tomorrow to see if it's that.

No MOT slots today so wont be getting her back and the full rundown till tomorrow.

Anonymous · February 26, 2004, 13:15

Well took mine yesterday for a re-check. A reset of the ECU and a clean of the O2 sensor brought everything down but still a fail. Cue the e-manage and a A/F map. s:D

s:D

Results in the end

CO allowed 0.30 result 0.00%
HC allowed 200ppm result 3ppm
Lambda 0.970-1.030 result 1.030 !!!

Cat screwed or not it's sorted. It was, mind you, a battle as it was pretty obvious the ecu kept adjusting against the e-manage's values to try and level it out, and the more fuel i took out the CO went down but the lamda went up, hence the 0% CO and at the limit lambda. 3/4 of an hour to map it so it held the values but they're now saved for next year.

I did have to swop the two O2 sensors over in the end as the first one which is where both banks read from would not adjust right at all. The second one that was just used as an bung for the hole, was moved to the No1 slot and it went alot easier.

Conclusion is, if anyone else has this problem, the O2 sensor was faulty.

DAZ400 · February 26, 2004, 13:41

I am coming to the conclusion these O2 sensors may not be as reliable as we would like.............. s:twisted: :twisted: s:twisted:

GSB · February 26, 2004, 13:43

Quote from: "DAZ400"I am coming to the conclusion these O2 sensors may not be as reliable as we would like.............. s:twisted: :twisted: s:twisted:

Well, to be fair, you turbo boys are using them at temperatures a little beyond what the original designer had envisaged, so you're going to have to expect them to have a shortened lifespan.

Sam · February 27, 2004, 13:30

Sorry all - didn't get a chance to update yesterday.

As we suspected it was the O2 sensor, the final one in my case, that was faulty/contaminated when the CATs broke up.

Got it changed and passed:

Fast Idle (3000rpm)
CO Allowed 0.3 Actual 0.2
HC Allowed 200 Actual 8
Lambda 1.03 Actual 1.02

Anonymous · February 27, 2004, 13:39

Looks like we both had same problem.Thanks for the update. s:)

s:)

mph · February 27, 2004, 17:19

My results:

CO Allowed 0.3 Actual 0.25
HC Allowed 200 Actual 150

Anonymous · February 27, 2004, 17:51

Martin, have you ever replaced your O2 sensor?

mph · February 27, 2004, 18:00

Nope.

Notes I should have previously included:

- No pre-CATs (obviously).
- Custom position of header O2 sensor.
- Single sensor with clever box'o'tricks to split signal.
- No primary CAT.
- A 'conditioner' on the final O2 sensor.