mot emissions, no cat and ecu?

with a fully programable ecu, rather than replace the cats for MOT would it be possible to make a "clean" map and still pass without them?

i guess its possible, but you have to run it so lean that it wont be driveable

just download the "butterflys from the exhaust" map just before the sniffer test and revert back as soon as it's done

i think if you run too lean the emissions get worse.

i also think i can remember something about honda messing about with a cruising AFR of 17:1

nobody got any input on this?

it's looking a bit trick to do this but i guess there is no finding out until the analyser is up the pipe.

the test is designed to test the cat specifically. the test (basically) is as follows:-

CO is measured at idle and then fast idle (2500-3000 rpm) and compared to a manufacturers spec in the test book, probably something like 0.5% at idle and 0.3% at fast idle. with the CO in spec then the HC are measured at idle and again compared to manufacturers spec in the test book, probably

so the trick is to have low CO and low HC at the same time, which is tricky without a cat. i thought they where two separate tests, which would be quite easy. it's tricky because running leaner (>14.7) produces less CO but more HC and running richer (

in theory, i'm going to get the CO just in limit with the fuel map and then try and bring the HC down enough with the ign advance.

does anyone have an analyser report sheet for a decatted supra?

would any specific fuel be cleaner?

any useful (fuel) additives?

any other useful tricks? (apart from the friendly MOT man who doesn't do emissions tests and putting the cats back on)

I would of thought this would effect your LAMBDA readings running too lean. IT has to be withing a certain range, not just below a certain limit.

Its not bad like CO or HC's, but they will still fail you on it.

I'm working on one for my emange, drive it there, put the probe up the exhaust, laptop over the new map, test, laptop over original map.

hmmm, it didn't say anything about being in a lambda range in the literature i read but it would make sense and it seems to be the case with hornets fail sheet. i wonder what happens with the honda lean burn engine design, that doesn't run at lambda 1?

that would still give you a legal range of 14.4 -> 15.2 ish AFR, maybe enough t make the difference??

I'm working on one for my emange, drive it there, put the probe up the exhaust, laptop over the new map, test, laptop over original map.

when are you doing it?

hornets failed test results:-

Fast idle speed - CO =

Second Fast idle - CO =

lambda - 0.970 - 1.030 - mine = 1.040 = Fail

Fast Idle test - HC =

Second fast Idle test - HC =

sort of 75% through it, but I need to get back upto my friendly MOT that have been letting me use there MOT gas tester thing. I won't be able to get back there for a few weeks due to work. But all I am doing is leaning it off a little around the 4000 rpm range to bring down the crap that comes out of the exhaust.

neat, what sort of numbers have you got so far?