High Lambda Figures

crankshaft · December 21, 2005, 01:04

I just did a search & found 3 threads, but there did not seem to be an anser so..

My cats are gutted, my Lambda figure was 1.02 with a max permissable of 1.03 !

What would be a likely cause of this ??

Thanx

so.simple · December 21, 2005, 01:34

The main cat is knackered?

crankshaft · December 21, 2005, 09:48

I certainly hope not s:(

s:(

Could it be that the petrol is 'stale' - It's been in the tank for 4 months as the car has been garaged since August ?

PeterC

Anonymous · December 21, 2005, 10:30

Just lambda? Or are other emissions out as well?

James

Slacey · December 21, 2005, 11:08

I've got this issue to sort out as well - the car is due an MOT (well, a while ago actually...) and I had an emmisions test done by my dealer when I was last there out of interest - it passed on the emmisions part but failed on the lambda test. My guess for me is that I am running rich for the turbo and only have a small race cat in place. For a stock N/A car I would say that it definately points to a poorly cat as the car if anything runs a little lean as standard.

markiii · December 21, 2005, 11:50

can anyone explain exactly what a lambda failure is?

I understand teh emmisions particulates stuuff but lamda is rather confusing.

aaronjb · December 21, 2005, 12:27

Quote from: "markiii"can anyone explain exactly what a lambda failure is?

In the tested conditions (I think it's warm idle, but it could be fast idle too) the lambda reading (taken from an exhaust sniffer) must be close to 1 (stoic, I believe - so 14.7:1 A/F).. I can't remember the lower limit, but it's quite a strict limit.

IIRC, E&OE etc

markiii · December 21, 2005, 12:59

but was is lambda?

so.simple · December 21, 2005, 13:03

"Lambda Sensor" is another name for "O2 Sensor". They're one and the same.

markiii · December 21, 2005, 14:47

that I kind of figured.

however a lamda failure isn't a physical 02 failure, since they aren't using our 02 sensors.

Sio I assume we are simpl;y refering to and overly rich AF Ratio as read by teh probe they shove up teh tail pipe?

in which case simply increase teh correction factor of the emanage so that it backs of teh injectors more? hence it will run lean?

so.simple · December 21, 2005, 14:52

Right. I didn't know crankshaft had an eManage.

markiii · December 21, 2005, 14:56

shoot me now he doesn't

I read Slacey's post and got turbo sidetracked. s:oops: :oops: s:oops:

Tem · December 21, 2005, 15:10

Quote from: "markiii"however a lamda failure isn't a physical 02 failure, since they aren't using our 02 sensors

Yeah, basically it means the mixture is off. But since the ECU uses to O2 sensors to make the mixture stoich, it probably means the sensors have worn down.

That's for a stock car anyway, once you mod it, it might be anything s:lol: :lol: s:lol:

Slacey · December 21, 2005, 15:37

Right, my MOT is tomorrow so I guess I will have to deal with this issue rather soon! Whether it passes or fails on the Lambda reading I will ask for some detail as to what the test is for and what it looks at so we will have a definitve answer.
Ian (mr-s_turbo), if you are reading this expect a phone call if I fail to get those tips you mentioned a while back s:wink: :wink: s:wink:

crankshaft · December 21, 2005, 16:13

Hi;

Mine is Normally aspirated but unichiped & setup on a rolling road by millway 1 year (2000 miles) ago.

Here's the full set of readings from the crypton gas test done by kwik fit during the MOT yesterday:

Co Level---0.0 %
HC Level---34 ppm
Lambda----1.02

I have the performance curves from Millway but not the Emissions tests !

I have a feeling that my stale petrol may be a contributor ?!

PeterC

PS: Are the o2 sensors resistive ?? - could they be 'tweaked'

Tem · December 21, 2005, 20:24

Quote from: "crankshaft"Are the o2 sensors resistive ?? - could they be 'tweaked'

They are actually voltage generators...but like any electrical stuff, you can alter the signal s8)

s8)

Anonymous · December 21, 2005, 22:22

I'm here Sean, if you need me give me a call.

The problem when the lambda is high is definatly O2 related (if the cat is fine), i couldn't get mine to pass my first year turbo'd and in the end i swopped the 2nd O2 sensor that isn't used on my setup for the first, i also cleaned it with carb cleaner, and i got better results.

Now it's the wideband in, it is better but it has failed on the last 2 MOT's through high lambda. The way i get through is to reduce the amount of fuel with the e-manage but the problem is you don't actually remove any fuel, you increase the amount of air,as it's impossible to minus duty from the injectors. So the bloody CO level goes sky high and as the stock ecu kicks in trying to fight the emanage to get stoich, the fun begins trying to level out the CO and lambda within limits. You need a patient tester that will run a few tests as you play with the emanage to get the pass result.

This obviously helps no-one that hasn't got a piggy back ECU that they can alter fueling (or a flashy standalone eh Tem).

So from experience i can say if your lambda is high then try cleaning your O2 sensors, if no difference they are knackered or as said, the main cat is dead.

spit · December 22, 2005, 17:38

Quote from: "mr-s_turbo"Now it's the wideband in, it is better but it has failed on the last 2 MOT's through high lambda. The way i get through is to reduce the amount of fuel with the e-manage but the problem is you don't actually remove any fuel, you increase the amount of air,as it's impossible to minus duty from the injectors. So the bloody CO level goes sky high and as the stock ecu kicks in trying to fight the emanage to get stoich, the fun begins trying to level out the CO and lambda within limits. You need a patient tester that will run a few tests as you play with the emanage to get the pass result.

Looks like I'll be coming your way for tweaking advice too Ian s:wink: :wink: s:wink:

I'm up for MOT in 2 weeks, so popped in to have a chat with my friendly testers and a quick probe job today s:shock: :shock: s:shock: . At idle, my wideband gauge indicated good stability around stoich, and the MOT machine showed Lambda a shade over 1 (1.073).

But I tried a few rev ranges and can't find a point where both CO and Lambda pass. Seems to be one or the other.....B*ll*x!

The range for a "pass" on both CO and O2 seems very tight. I can't quite get my head round why a FI '2 with flat EManage maps would struggle compared to a N/A '2 under test conditions (closed loop idle). Can someone explain? Is it because of a less efficient high flow Cat?

Thankfully, my garage are happy to let me play around with settings (EM and Wideband analogue's switching point) until we can register a pass s:lol: :lol: s:lol:

Anonymous · December 22, 2005, 18:08

It has to be the cat as nothing else is changed (that can affect the emmisions). That, and the MOT stations test equipment, how often are they cleaned and calibrated s:? :? s:?

It is strange how my WB shows stoich or slightly leaner, and the station says it's too rich, but i did try another station to see if it was their machine but got the same results, now i've got you lot going through the same so i know it's not my setup s8)

s8)

If you need me Ste give me a shout.

Comer · December 22, 2005, 22:43

Just a quick blast from the past.

My old car failed on the Lambda (def o2 related) and there was leak in the gasket between the main cat and the H&S exhaust. Check those studs are tight and / or replace the gasket if necessary.

Slacey · December 23, 2005, 07:53

I had my MOT last night and I asked the guy what exactly the Lambda test was. He stated that the perfect reading was 1 (he did give the technical jargon name of the figure but I can't remember, but this equates to stoich) and that any reading OVER meant it was running lean and any figure UNDER 1 was running rich. This surprised me somewhat as I'd always figured that I would run rich, but it seems that both times I have had a test that as I was around 1.3 I am running lean.
Anyway, I didn't realise until I got there but the testing station I used was also the base for Severn Valley Motorsports (Ford specialists) with aeons of tuning experience, so 5 minutes later it passed s:wink: :wink: s:wink:

Tem · December 23, 2005, 08:04

Quote from: "Slacey"(he did give the technical jargon name of the figure but I can't remember, but this equates to stoich)

Stoichiometric?

Quoteany reading OVER meant it was running lean and any figure UNDER 1 was running rich

Yeah, you can convert these to AFR, if you're more familiar with these s;)

s;)
AFR=14.7*LAMBDA

markiii · December 23, 2005, 08:24

Quote from: "Slacey"I had my MOT last night and I asked the guy what exactly the Lambda test was. He stated that the perfect reading was 1 (he did give the technical jargon name of the figure but I can't remember, but this equates to stoich) and that any reading OVER meant it was running lean and any figure UNDER 1 was running rich. This surprised me somewhat as I'd always figured that I would run rich, but it seems that both times I have had a test that as I was around 1.3 I am running lean.
Anyway, I didn't realise until I got there but the testing station I used was also the base for Severn Valley Motorsports (Ford specialists) with aeons of tuning experience, so 5 minutes later it passed s:wink: :wink: s:wink:

come on then more info, what did they do to get it to pass?

Slacey · December 23, 2005, 10:13

They jiggered the Emanage map to suit, then returned it to my original map.

aaronjb · December 23, 2005, 12:19

Quote from: "Slacey"They jiggered the Emanage map to suit, then returned it to my original map.

I have a feeling Mark was after what they did to your eManage map, Sean s;)

s;) s:D

s:D

I guess perhaps add some injector duty (if it was lean) and perhaps adjust the timing a little for a more complete burn (to lower the CO figure back down again) - probably advance the timing a little, at a guess.

Sound right?

[edit] Oops, got advance & retard backward s:oops: :oops: s:oops: [/edit]