Author Topic: Help required with MOT failure on emissions  (Read 554 times)

mavbill

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Help required with MOT failure on emissions
« on: September 12, 2021, 09:25:52 PM »
Hi all,

I just got the wife's car back from the MOT garage. Its a Honda Jazz 2008 1.2 Petrol Engine

The two main failures are: -

Parking brake efficiency below requirements [1.4.2 (a)(i)]
I am a little bit confused about this one. Parking brake is the hand brake, right?
I applied the handbrake to the car and tried moving the car forward and backwards, but the car could hardly move so not sure how this would be an MOT failure.


Exhaust carbon monoxide content at idle exceeds manufacturers specified limits (8.2.1.2 (b))
A little bit of context. The EML on the car has been on for a while. I was told issue was the EGR valve. Anyway, before this MOT I decided to buy an egr/carb cleaner. I removed the egr valve and cleaned it.
The car was completely worse, running roughly and stalling on idle. At this point I did an obd scan and codes for egr valve and misfire on cylinder 2 came up. I cleared both codes and purchased another egr valve from the breakers yard. Car started ok, runs fine, EML light stays off and the cylinder misfire code has not returned.

The car's catalytic converter was stolen off the car just over  2 years ago and we had to buy a new exhaust online so it’s gone through 1 or 2 successful MOT's

I took the car for MOT and it was failed for the above. My knowledge in this area is non-existent so was wondering what I need to do to fix the issue. Attached is the MOT report of the failure. I have also included the Live reading from the OBD Car Scanner & Torgue app


Thanks


embee

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Re: Help required with MOT failure on emissions
« Reply #1 on: September 12, 2021, 11:09:26 PM »
Can you find the emission readings for the previous MOTs with the replacement cat? This might give a useful clue as to whether the replacement was performing as one would hope or whether it was marginal in previous years.

The lambda is within limits but it is slightly on the richer side of stoichiometric, possibly more than I'd expect from a std car of that era. It would be useful to see some typical figures for other Jazzs of that age. Being biased to the rich side will increase the raw HC/CO so the cat must be working efficiently in order to cope. The CO are fails but the HC is also high.

Low conversion efficiency can happen if the cat is not hot enough, some cars are a bit marginal if the MOT tester doesn't make sure it is hot enough though I'd expect a std Jazz to have a pretty high conversion rate, an aftermarket cat is an unknown quantity in that respect.

It could be that the lambda sensor isn't performing very well, or there is a poor electrical connection (voltage goes high with rich mixture, resistance could suppress the voltage seen by the ECU so it could potentially have to go richer than it normally should to get the feedback response).
« Last Edit: September 12, 2021, 11:16:03 PM by embee »

mavbill

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Re: Help required with MOT failure on emissions
« Reply #2 on: September 13, 2021, 09:21:18 AM »
I don't have previous years mot results as I tend to bin them. I tried looking on the got (check MOT) site but it does not show emissions info. I wonder if the MOT place could still have/print me the results ....

Taking a stab in  the dark, could the O2 sensor be the issue?. Also is it something a mechanic can figure out easily?

sparky Paul

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Re: Help required with MOT failure on emissions
« Reply #3 on: September 13, 2021, 07:18:50 PM »
It could be that the lambda sensor isn't performing very well, or there is a poor electrical connection (voltage goes high with rich mixture, resistance could suppress the voltage seen by the ECU so it could potentially have to go richer than it normally should to get the feedback response).

+1

As said above, an "Italian tune-up" before the test might help, but emissions look like excess fuel - I would also suspect front o2 sensor. Check the sensor connections are all in good order. On diagnostic, check live data from front o2 sensor for expected voltages & oscillation. Otherwise, substitute a known good sensor.

Shouldn't be difficult for a garage to solve.

mavbill

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Re: Help required with MOT failure on emissions
« Reply #4 on: September 14, 2021, 09:20:25 AM »
Thanks guys.

Just reading top about what Italian tune up means, So I'll do that 1st and read the live data again to see if anything changes in the readings. Its booked in to the mechanics tomorrow as well.


mavbill

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Re: Help required with MOT failure on emissions
« Reply #5 on: September 14, 2021, 03:33:44 PM »
Some good news!.

I added Redex to the petrol and gave it the Italian tune up blast on the motorway, Engine now run's smooth, silently idles at low rpms. All the sections of  emissions test in the obd diagnostic reader is  now showing as passed. I think think/hope it should pass the emissions at the test centre ....(fingers crossed!).

Now I have to deal with what's left, i.e. handbrake and leaking tie rod.

Thank guys.

Neil Ives

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Re: Help required with MOT failure on emissions
« Reply #6 on: September 14, 2021, 03:45:03 PM »
When I was young I always drove old bangers. A fast and long drive would give them a tune-up, (decoke) Another noticeable thing was an improvement in performance when it was raining.
Neil Ives

zzaj

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Re: Help required with MOT failure on emissions
« Reply #7 on: September 14, 2021, 07:23:12 PM »
Some good news!.

I added Redex to the petrol and gave it the Italian tune up blast on the motorway, Engine now run's smooth, silently idles at low rpms. All the sections of  emissions test in the obd diagnostic reader is  now showing as passed. I think think/hope it should pass the emissions at the test centre ....(fingers crossed!).

Now I have to deal with what's left, i.e. handbrake and leaking tie rod.

Thank guys.

Well done - all fingers crossed too!

Let us know the result.

culzean

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Re: Help required with MOT failure on emissions
« Reply #8 on: September 14, 2021, 07:47:40 PM »
I am a great believer in redex, have seen it perform pretty much miracles with engines over many years,  it is the cheapest thing to try as well.......

Engines do not like constant local short journeys and low revs, it causes all sorts of mischief. I have found redex and a long journey making the engine work can work wonders.  Our Jazz now done 300+ miles to Cornwall ( long delayed holiday ) and I put a whole 500ml bottle of redex and a tank of 99 octane in before the journey and it really feels like a different car, seems to have much more pull from low revs, smoother tickover, cleaner pickup and running all round. The MPG fibometer saying 56 at the moment after M5 / A30 blast and some local ( hilly ) miles..
« Last Edit: September 14, 2021, 07:52:05 PM by culzean »
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

culzean

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Re: Help required with MOT failure on emissions
« Reply #9 on: September 14, 2021, 08:45:12 PM »
When I was young I always drove old bangers. A fast and long drive would give them a tune-up, (decoke) Another noticeable thing was an improvement in performance when it was raining.

Two stroke motorbikes used to run much better in cooler damp conditions.
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

E27006

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Re: Help required with MOT failure on emissions
« Reply #10 on: September 15, 2021, 03:16:03 AM »
When I was young I always drove old bangers. A fast and long drive would give them a tune-up, (decoke) Another noticeable thing was an improvement in performance when it was raining.

Two stroke motorbikes used to run much better in cooler damp conditions.
When the 500cc GP bikes such as the Honda of Mick Doohan were north of 170bhp,  the Honda 2-stroke had a water injection system,  the Harrier VTOL has a water injection system for the Pegasus jet engine, my Metro 998cc of 1982, the engine seemed to run better when driving through the country roads when there was plenty of mist trapped by the trees. I believe the mist is turned into steam during combustion in the cylinder,  steam can be a very quiet as driving force comparing steam traction engines with vintage industrial engines at country fairs

mavbill

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Re: Help required with MOT failure on emissions
« Reply #11 on: September 16, 2021, 01:25:17 PM »
Ok, I am not so pleased with the outcome of the MOT even though it 'passed'.

After my Italian tune up I had all other outstanding faults done by another garage before taking it back to the test centre.

Tester told me quietly that all is fine however he put another car through the emissions bit of the test.

My genuine belief is that the car should sail through the emissions rather than someone thinking they have done me a favour. So its either a case of tester (a) Using another car from the start of emissions test rather than mine thinking it would fail OR (b) It failed and then he used another car.

I did not want to go about interrogating him considering it was a busy place so I am still left with a burning desire to know the 'real' emissions results. 

Is it possible for me to go someplace else and have an emissions test done again but not part of the mot?.


UKjim

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Re: Help required with MOT failure on emissions
« Reply #12 on: September 16, 2021, 07:18:26 PM »
That Tester is taking one hell of a risk with his livelihood.


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E27006

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Re: Help required with MOT failure on emissions
« Reply #13 on: September 16, 2021, 08:54:39 PM »
That Tester is taking one hell of a risk with his livelihood.


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The Mot tester is taking a risk with his licence to test, but this "piggybacking" of using a substitute car to fake the test figures is not uncommon.
i would simply carry on driving the vehicle, even if you Jazz is slightly out of specification, there are far more damaging  cars on the road for pollution, Range Rovers and the majority of diesel cars.

Andyroo

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Re: Help required with MOT failure on emissions
« Reply #14 on: September 18, 2021, 07:29:11 PM »
I've just joined the Forum and am also suffering with emission problems (with my Jazz, that is...) It's a 2005 1.2 litre engine, with 110K miles, which suffered a catalytic converter theft 3 years ago. A patented (non-Honda) one was fitted, together with a new exhaust system & O2 sensors and all has been well for several MOTs since. So far fo good....

At the last MOT it failed for headlamp beam (an easy fix) and emissions, which, to quote the tester, were "all over the place!" He did a diagnostic for free, which threw up a failed pre-cat O2 sensor error. He also suggested new plugs.

I went a bit over the top, and fitted eight new coil packs. eight new plugs and a new lama probe.... The test result was still a fail, with the emissions every bit as bad as before.

I'm a retired mechanic, so am not a complete novice with cars, but this has me foxed! Poor compression in one cylinder? Worn rings? Are there any other items in the engine that are worth examining and possibly changing? I love this little car, it's as cheap as chips to run (NORMALLY!) and this is the first serious problems it's had.

Any thoughts out there in Jazzland?
I don't know what you've done to me, sir, but you've done me the power of good!

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