MOT failure - emissions

[Peter Carmichael]

and ...

 

... this good advice

 

1. Ensure all of the exhaust is properley sealed (with HT silicone if possible).

2. Silicone and lead are poisonous to a CAT so be careful not to let any get in to the CAT.

3. You will need a decent sized CAT that works.

4. The CAT will only work if it is at the right temperature and the lamda value is correct.

5. Once you get it set up correctly you will see a major reduction in your measured emissions and wonder why you thought it was so difficult in the first place.

---

[oilyhands]

... no mention of closed loop settings

 

Get your reading glasses on chief car wally.. 😬

 

You dont need any self-learning, you just need to lean the fuelling off at idle and at 0 load 2500-3000 and turn on closed loop. It takes about 20 minutes to do this at a friendly MOT centre.

---

 

I've put around 50 modifed K series through MOT's, it's a cinch

 

oily

[k80rum]

Thanks Peter, and point taken..

 

I should have been more careful with my wording, because reading it back, that looks exactly like what I'm offering.

 

To clarify:

 

What I should have said was, if come MOT time anyone feels or knows that they will need to adjust their fuelling around the MOT sites, the Emerald-supplied documentation helps to explain the process involved and the two map files (the normal and the MOT variant) might be a useful aid in understanding the differences involved when looking at the map (very small changes at the right area can be enough to make all the difference).

 

I don't mean to propose the MOT variant will get someone through the MOT. Even on the same car, passing or failing is also likely to be subject to variances introduced by the test operator and the equipment.

 

Closed loop would be hugely beneficial (for wideband users?) in trimming the fuelling, based on what the lambda sees and comparing it to the AFR target. It's what I plan on using at my MOT map test sites, with the corresponding AFR targets set at or below the MOT target figures.

 

My understanding is that adaptive mapping mode should not be used around the idle sites in any case, since it makes for a lumpy idle. Closed loop is much better at these sites.

 

I hope that looks a bit more reasonable..

 

Darren E

 

K80RUM Website and Emerald maps library

 

Superlight R #54

 

 

[Nov-07]

My MOT experience seems to have stirred things up ❗ I am sure that the reason for the original problem (high CO levels) was that the operator allowed everything to cool down before the test, and was unskilled at maintaining a constant engine speed. The actual trimming of the injection map at 1,000 and 2,500 rpm was very minor, only one or two "clicks", and the procedure followed was exactly that recommended by Emerald, and by Oily. The car is fitted with a catalyst, so there should not have been a problem in the first place.

What was significant about the test was that the operator was unswayed by the "N/A" entries on my SVA certificate for CO and HC emissions, and this is consistent with the latest guidance from Caterham/Simon Lambert (see 7FAQs). The mechanic was evidently confused about the likely differences between Q-plated and other self-built cars. He said "if it had a Q registration I would pass it". This seems to be an area where the regulations need clarifying.

[jeremybu]

Peter, I am not scared silly by talk of MOT maps. I realise it's straightforward passing the MOT if the ECU is adjusted right, but I needed some help to understand how to do it.

 

The instructions I have for leaning off at the required revs are clear enough, so I think the MOT side of things can be resolved this week.

 

Moving on from that.

 

After checking my current setup, I show that:

 

Closed loop is not active - should I have this applied for idle purposes etc?

 

Fuel cut off is not active - is this recommended and what settings should I use for this if so?

 

AFR target is 12.5 on every site which I assume isn't helping the CO at test time and means the car is running rich everywhere. It seems to me this will need to be corrected and I have the RR session booked as previously mentioned. However, is there another way this can brought nearer to 14.7 beforehand with the narrowband Lambda and no special kit.

 

In the end I suppose, I want to know if once the MOT is passed, I should leave any further adjustment to Dave Walker as:

 

1) really I have no way of doing it myself.

 

2) the car running rich at 12.5 will cause no damage if I wait for 1).

 

Thanks

 

1.6 SV - GJ02JLO - If there's one thing I've learned, it's that it should have been something else.

 

Edited by - jeremybu on 24 Feb 2008 17:42:23

[Peter Carmichael]

The instructions I have for leaning off at the required revs are clear enough, so I think the MOT side of things can be resolved this week.

---

 

When you make changes, review them in the graphical view of the map. The ECU cannot hope to deliver appropriate fuel if the map is up and down all over the place. The map should have gentle gradations from one site to the next.

 

Closed loop is not active - should I have this applied for idle purposes etc?

 

Closed loop is useful for many running conditions, but only once the base map is close enough. Closed loop means running with a naroowband lambda switching the fuelling either side of lambda 1 (14.7:1 AFR). This is required for healthy normal operation of the cat and is usually applied at most cruise sites, giving good fuel economy, with the feedback assuring that the fuelling is where it should be. Step 1: good base map. Step 2: closed loop with a narrowband lambda. It should definitely be active for the MOT test points.

 

Fuel cut off is not active - is this recommended and what settings should I use for this if so?

 

Fuel cut-off is difficult to implement well. Fuel cut-off causes a fuel deficit in the inlet tract next time you crack open the throttle. This requires some compensation using Load Site 1 fuelling sites (sometimes) and accel fuelling. Many people give up on trying to get it to work well because it results in a jerky on/off throttle response and kangarooing.

 

AFR target is 12.5 on every site which I assume isn't helping the CO at test time and means the car is running rich everywhere. It seems to me this will need to be corrected and I have the RR session booked as previously mentioned. However, is there another way this can brought nearer to 14.7 beforehand with the narrowband Lambda and no special kit.

 

AFR target is only for self-learn with the wideband lambda. It is irrelevant with narrowband and open loop running. The narrowband, by definition, has a characteristic response at 14.7:1 AFR and can exactly be used to trim the low revs running positions to 14.7:1.... but it is not always easy to do on the road.

 

In the end I suppose, I want to know if once the MOT is passed, I should leave any further adjustment to Dave Walker as:

 

1) really I have no way of doing it myself.

 

2) the car running rich at 12.5 will cause no damage if I wait for 1).

---

 

It isn't running at 12.5:1. It has no way of knowing what it is running at, at present. Could be all over the shop. Highly likely if your idle is causing 9% CO.

 

The car does need a mapping session.

 

 

Edited by - Peter Carmichael on 24 Feb 2008 17:34:13

[Johnty Lyons]

Peter I usually find that ticking the overrun Auto box in the Throttle pot setting page looks after the overrun fuelling fairly well provided the car has been mapped properly

 

Always works for me anyway.

Just my tuppenceworth

jj

 

jj

N.I. L7C AR 🙆🏻

Membership No.3927.

 

[jeremybu]

OK all, thanks very much for now.

 

1.6 SV - GJ02JLO - If there's one thing I've learned, it's that it should have been something else.

[robmar]

Peter - 😳 but that is not the only thing i have done recently to reduce the weight will see how it goes emissions wise and work on aplan from there

 

it is the fog light, horn and driving lights that are currently non operational that it will fail on, and number plates if that is in force ☹️

 

rob 😔