Emmisions test?

DanW · Post by **DanW** » Wed Sep 22, 2004 9:05 pm

does anyone have their emmisions test results?

what should the lambda read as well?

cheers

Dan

Tahrey1043 · Post by **Tahrey1043** » Fri Sep 24, 2004 1:16 am

somewhere, from the last MOT, but you'll have to call out the midlands metropolitan constabulary with their shovels and sniffer dogs to find where that "somewhere" is...

somewhere around 1.0 volts isn't it? 1.2??

metz · Post by **metz** » Fri Sep 24, 2004 7:35 am

MInes going in for its mot in the next couple of weeks so i may be able to tell you then.

DanW · Post by **DanW** » Fri Sep 24, 2004 11:14 am

cheers lads, I've got the figures here. I'm just trying to see if the lambda is healthy at all. Could possiably be within limits but not healthy couldn't it ?

LogIK · Post by **LogIK** » Fri Sep 24, 2004 4:42 pm

The Lambda should read 1.00. It performs a calcualtion of every readout as kind of like a checksum, which should equate to 1.00, if it's healthy.

DanW · Post by **DanW** » Fri Sep 24, 2004 6:02 pm

it's got
Lambda = 1.038
on the emissions test.

Tahrey1043 · Post by **Tahrey1043** » Fri Sep 24, 2004 9:02 pm

The Lambda should read 1.00. It performs a calcualtion of every readout as kind of like a checksum, which should equate to 1.00, if it's healthy.

huh? isnt it just some simple analogue probe thingy?
the 1.0 i was referring to was the voltage output from the probe when the exhaust gases come out fully combusted... too rich a mix makes for a change in one direction, and too lean, the other way (though i'd be screwed to tell you which is which)

1.038 sounds fine as it's a good few tenths of a volt difference the probe can put out, and the middle ground voltage fluctuates slightly with the various random factors that act on the engine anyway (and in it's own gently oscillating feedback loop - if you have a tacho, push the throttle at tickover enough to get it up to around 2000 and watch the needle waver back and forth a smidge every second or so)

DanW · Post by **DanW** » Sat Sep 25, 2004 1:48 am

Tahrey1043 wrote:
if you have a tacho, push the throttle at tickover enough to get it up to around 2000 and watch the needle waver back and forth a smidge every second or so

yeah I noticed this

might adjust the idle point back down to what it was originaly, I've been playing around in the traffic the last few days and I can pull of with out and throttle

. Sounds like it might also be in for some new leads (a whole set this time, the last change looked like the guy only changed one)

Tahrey1043 · Post by **Tahrey1043** » Sat Sep 25, 2004 3:15 pm

how does one adjust the idle point at all, then?
thought it was kind of fixed by the ECU

mebbe you've tweaked the throttle stop so it's not actually idling, and thats why the emissions are borderline

(er, was it yours that just scraped it?)

LogIK · Post by **LogIK** » Sat Sep 25, 2004 3:53 pm

1.038 is a little high. That should have failed it's MOT, but since they measure it to 2 DP, it may have scraped through. The max it should be is 1.03 IIRC. The Lamba should be reading 1.00, ideally.

Tahrey, the checksum calculation that I mentioned was something a professional car technician told me, however, we were talking about modern cars at the time, so maybe it is different on older cars (i.e analogue) and what you say is right, but that's what I've heard.

My Lambda reads 1.01.

Tahrey1043 · Post by **Tahrey1043** » Sat Sep 25, 2004 8:35 pm

well i'll bow out on this as you were talking to the actual tester!
maybe its something that happens in the ECU?

LogIK · Post by **LogIK** » Mon Sep 27, 2004 6:51 pm

Well, it wasn't actually the MOT tester who told me, but it was a guy who makes a living from diagnosing car problems by plugging his magic computer into it. He had these special adaptors to fit any car. The kit he had was amazing!

He has a computer programme that then reads every readout, such as C02, HC, C01 and so on. It then shows what the Lambda reads, and he told me that the Lambda is a calculation of all other readouts, which should always be 1.00.

I suppose it's a bit like ISBN numbers that have the check digit on the end to verify if every other digit is as it should be, or checksums when transfering data across networks. Maybe not that complex, but the same principle.

Tahrey1043 · Post by **Tahrey1043** » Mon Sep 27, 2004 7:34 pm

C02, HC, C01

it does all that?!

thought you needed to hooky the cars exhaust up to a sampler doobry, thats quite special that

LogIK · Post by **LogIK** » Fri Oct 01, 2004 3:13 pm

Ah yes. Now I remember! He used an exhaust probe aswell.

So the exhaust probe may have worked out the Lambda figure by doing the checksum, then matched that to what the actual Lambda probe is reading to see if it is reading correctly.

Makes more sense now!

hardhitter · Post by **hardhitter** » Fri Oct 01, 2004 7:05 pm

Lambda is only checked on post Aug 92 cars, on the catalyst emissions test.