Paulo P

iTrader: (42)

Hi everyone

I put my car on the rollers at g-force last Saturday and I've been getting conflicting opinions to the lambda readout on this graph. Some people are telling me the car is running too rich and someone has now said that the car is running a bit lean especially between 5,600 rpm and 6,000 rpm and now it's left me a bit confused

What do you reckon to it please?



Thanks

Paulo P

iTrader: (42)

nobody got an opinion on this?

RichWalk

Paul, if you are using a normal narrow band zirconia lambda, the average mix should be 0.45v, if its running lean it will be down towards 0.2v and conversly if rich, it will be around 0.8v, so as your revs increase its getting richer.

Normal lambda only wo*k within a small tolerance around the 0.45v average, after that they are largely in-effective at telling the ECU that the cars is over/under fuelling. The Bosch 5 wire 'wide-band' type wo*k over a larger voltage range and using a 'current-pump' allow much more accurate adjustments to the ECU, hence better fueling.

ZEN Performance

The scale is in lambda direct, not voltage.

It's okay, perhaps a little lean on the plateau near 0.8lambda between 5500 and 6000rpm.

Paul

Paulo P

iTrader: (42)

Thanks Paul that confirms what someone else had said What can I realistically do to cure this? I am open to opinions about what to do next.

Thanks

Delboy2

As Paul says - it is a little lean at around 12.4 AFR, is there a boost spike/step @ 5.5k?

Cheers

Tripple'O G

Alloy and I had the exact same readout from G-force and again they said our cars were running "dangerously lean" which is dribble.........don't worry about it mate....

Paulo P

iTrader: (42)

There wasn't any boost spike as such but the boost was wondering up and down and the graph wasn't straight like it should be. I wasn't impressed with that but it stays around the same level. On the road you get a real stab in the back at 5.5k though

G-force said the car was safe to me but I've been hearing comflicting opinions since showing the graph.

RichWalk

Whats the difference? I thought you could only read AFR's in milli-amps using the wide-band sensor, is there another test used? Or is it pure lambda where less than 1.0 is rich & greater than 1.0 is lean, so you simply percentile the diag's by the required amount to re-adjust?

alloy

As triple says i had an experience like yours. My STi was .84 on the lmbda at g-force and i was advised it was scary lean, so a week of conservative driving later I took it to TDi and their HKS power writer said it was rich and we "leaned" it out. I think stick to what your mapper says he knows the car etc.

Although you have to check these things on advice from others.

ZEN Performance

Lambda as a measure of AFR is the ratio of Stoich AFR, so lambda of 1 is 14.7:1 AFR.

You should take a little more care over what you quote me as saying, I never mentioned 12.4:1 AFR

A lambda of 0.8, the highest on-boost figure, translates to 11.76:1 AFR.

Paul

harvey

iTrader: (48)

11.76 :1 on full boost is a bit on the weak side.

Paul : Don't you think it is quite astonishing that people who frequent this board and are clearly capable of typing are incapable of reading the written word and sticking with it. Seems to be a common problem.

Delboy2

I converted from a table which appears incorrect when AFR = lambda * AFR(stoich)

ZEN Performance

Probably a table of lambda voltage Del, please be more careful and specific.

Harvey,

I agree 11.76 is a little lean, but 12.4 is OMFG lean!

Paul

Tripple'O G

Food for thought here.......

Went to G-force for a dyno and they stated my car was 271bhp and running dangerously lean (like yours Paul).....

I've just been to get my car mapped my Steve Simpson and straight away it made 319 before the mapping even begun.....and it's wasn't running lean, it was running spot on.....

So.........either Steve Simpson who has been mapping/tuning cars for a lot longer is wrong........or someone's got a naughty dyno.......