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MOT mapping a squirt
coyoteboy - 18/6/13 at 08:10 PM

So I've made a heap of changes to the tin top including new injectors, intake, intercooler etc and it's time to get it tuned up. Last time I tuned it on the road with a little help from my other half. This time it isn't MOT'd so no can do. I have it running, moving on the drive isn't an issue and my no load AFR values are pretty stable. Has anyone got their car through a MOT while not having a mapped ECU? Im thinking that if I just tune 2500rpm to within the lambda limits using the wideband it's about all I need? 1991, non cat test.

mark chandler - 18/6/13 at 09:09 PM

Non cat test is visual smoke, does it smoke a lot? If not you pass.

matt_gsxr - 18/6/13 at 09:16 PM

Tune the idle so no missfires and 14.7 AFR and it should be fine.

Maybe autotune with tunerstudio on the way to the MOT station and take the long way around.

They don't drive it during the test except for the brake test.

mad4x4 - 18/6/13 at 09:43 PM

So is the Non cat test a visual only , my zetec fell into the non cat but I can't get emmission correct to pass as garage use analayser and say fail

[Edited on 18/606/13 by mad4x4]

mark chandler - 18/6/13 at 10:34 PM

Above is for a tin top as per OP,s query, on an IVA'd kit it's different unless your kit is 20 years old.

MikeRJ - 18/6/13 at 10:54 PM

quote:
Originally posted by mark chandler
Non cat test is visual smoke, does it smoke a lot? If not you pass.


I thought the non-cat test was an emissions based test but with wider limits? That's certainly the case for normal tin tops.

coyoteboy - 19/6/13 at 07:17 AM

Non cat is still emissions based, limits are just higher. The visual test is for much older vehicles. I can get it to idle smoothly at 13:1 and sit at 14.7:1 @2500 but other than that I need a decent bit of time on the road. MOT station is 400 yards away so but might be able to be lost in the fields for a while lol



[Edited on 19/6/13 by coyoteboy]

matt_gsxr - 19/6/13 at 09:02 AM

I don't quite understand.

Surely idle tuning is all about tuning at idle.
Why would time on the road help (except to give it all a run to clean things up).

By my estimates, as long as it is firing cleanly on all cylinders then you will have no problem with HC, but for the CO you will need to have a stable idle with AFR of >13.5



Sounds like it is close, maybe increase the idle slightly, clean the plugs and take it along? The worst that can happen is it fails.

mackei23b - 19/6/13 at 09:20 AM

I took my laptop to the MOT station and changed the VE map to get a pass using the gas analyser. (I visited the garage before hand so they know what was coming and they were supportive to allow me a little more time to tweak the emissions)

I went form a fail (running rich) to a pass in under 20 seconds changing the map, you'll only need to tweak a couple of the load sites and it doesn't matter about the rest of the map.

Cheers

Ian

coyoteboy - 19/6/13 at 05:57 PM

quote:
I don't quite understand.

Surely idle tuning is all about tuning at idle.
Why would time on the road help (except to give it all a run to clean things up).

By my estimates, as long as it is firing cleanly on all cylinders then you will have no problem with HC, but for the CO you will need to have a stable idle with AFR of >13.5


I struggle to idle at >13:1 (low compression, batch firing injectors) and I'm not 100% convinced of the accuracy of my WB02 sensor. If they leave it idling for 10 mins it'll get heatsoak in the IAT sensor and the AFRs will drift to the point that it misfires.

Regarding time on the road - I'd like to have it easily hand-over-able, especially as it's permanent 4WD and they have to take it out to do the ticker-tape brake test, if they stall it/flood it/take it outside its safe zone that is currently tuned it's fooked. I can deal with that, but they won't and they'll just fail it. They are not overly helpful. They won't allow me to tweak the map in the center, they won't allow me to even BE IN the center when testing it "for insurance reasons, init".

All I can really do is tune it at idle to ~14:1 and hope it doesn't misfire much.

mark chandler - 19/6/13 at 06:10 PM

If your car was built originally without a cat then visual, cats became mandatory in Aug 1992 ( I think), I had an XJS that was made in march 1992 which was visual only as no cat fitted.

So back to the OP's query, his tin top car was made in 1991 so can be visual only if he pulls the cat, fit a cat and it all changes although it will be the very wide limits which you should achieve without a cat anyway.

coyoteboy - 19/6/13 at 09:31 PM

Mark, that flies in the face of the MOT testers manual (image above) and every mot I've had at different stations since 2004 with that car. It isn't a cat test but emissions limits still apply (1200 and 3.5&#8453. car was built with a cat but it isn't ever cat tested and doesn't have one now.

[Edited on 19/6/13 by coyoteboy]

matt_gsxr - 19/6/13 at 10:40 PM

Why not take it to a friendlier MOT station. Why support unpleasant people?
I don't think there are any rules that say you have to take it to one close by.

My experiences with MOT stations (and SVA) are only positive so there are some decent guys.

coyoteboy - 19/6/13 at 11:22 PM

They are hit and miss to be honest, depends who out of the 4 testers I get. I could take it to the local vosa centre, but other than that I don't know any who are not out to make a quick quid out of you. These ones are sort of a known evil lol. If anyone north of Glasgow could suggest one who will let me tweak I would give them a shot.

Back near my old house I used the same guy for over a decade and he was very helpful and let me help out some years, talking me through the whole test and why he was advising, failing or passing with a 'I know you will fix this as soon as you go home (and I would) so I will advisory it'.

[Edited on 19/6/13 by coyoteboy]

coyoteboy - 13/9/13 at 06:41 PM

just put off completeness, I tuned for 14.2 from idle to 3k, enabled ego with 10℅ authority and 14.4 AFR target. passed no questions asked, and it's barely drivable as that was the only region I paid more than a cursory glance at!