Hello im fitting a stacks AFR gauge to a mates car and wondered what the readings should be on it .

What should they be on boost , tick over .

I havnt got a clue and neither has he .

Its a stage 3 cossie .

Cheers .

Travis.

 

at idle, close to stoichiometric, 14.7 to 1, lambda 1

boost depends on the map that the car is running so consult whoever provided the map on the car

if you google it you'll find some rough estimates on what it should be under load, i assume the stack is a wideband as narrowband sensors aren't much cop

 

About 11.5 on boost and around 14.7 at idle

Steve

 

Cheers for that , so the higher the number the leaner it is .

 

Correct

You don't want it lower than 10 on boost either

Steve

 

Top info there. I never knew that.

 

Cheers for that 7ft steve .

 

For this application, it shouldnt really go under the mid 11s ideally as it starts to drink fuel if you do and there is no real need to run that rich.

On some cars with badly designed exhaust manifolds though you do need to be down that low just to control the temps.





The reason its a higher number for leaner, is that the ratio is part of AIR per part of FUEL.
So the less fuel in the ratio, the more parts of air per part of fuel.

Dont be surprised if you see 16s etc for a split second here or there when going on and off the throttle etc, its not an exact science on these cars so dont expect massively consitant results on every possible condition,they're a bit basic for that no matter who is mapping them!

 

Ive got a luminition AFR in my cossie , the one with the led's only and all the lights go out for a split second when i let the throttle off and on . I know there a bit cack but collins engineering said it wasnt far out when i had it RR tuned .

Might be buying a stack one myself , looks a nice neat bit of kit .

 

Is yours a narrow band sensor?
If so not worth a wank really TBH mate.

 

Probably is chips its one of these
http://www.newtronic.co.uk/new/suppo...structions.pdf
Doesnt say if its narrow or wide band though .

 

All sorted , his readings are 14.8 idle , 11.5 on full boost .

Very nice easy to read unit definatly getting one of these .

 

Steve

 

Narrow band, load of rubbish on a turbo car, worse than nothing in fact as it essentially lies to you.
At 14:1 it will read fully rich and yet on boost that's lean enough to risk melting.

 

Thought it might be a narrow band one . New stack one coming soon . To be honest i dont trust it , just looks cheap if you know what i mean .

 

Is it common for cruising conditions AFR to be above 14.7 by mappers, on say the webber ecu,s ?
Interesting thread .

Mike

 

If its a closed loop (lambda) ecu then it should held 14.7 anyway as it should correct, if its not then its not uncommon to run slightly leaner as you get better economy if you go just a touch leaner than that.

 

Cheers chip, its something i was thinking about for when mine gets a written or mapped chip with ( lean as possibly deemed safe) cruise conditions as i will do long journeys and every bit helps .

 

heres a simple little picture that might help some people, but as said normally richer than 12.6:1 for peak power,, i aimed for a bout 11.7:1 when i mapped my cosworth

 

My zetec turbo runs 12afr @2bar and 15afr cruse

 

Good stuff.

 

mines running 13.0 at 70mph , 12.5 idle and 10.2 on boost 1.5 bar at min, i take it that it far to rich

 

Yes

Steve

 

Glad this thread has popped up as I have just fitted one to mine!

I've got the standard 14.7:1 at idle and 11.5 on boost but see some real lean numbers when on off throttle like 19:1 be it only for a second and also up to 9:1!!!
when I first start the car (cold start) it idles with an afr of 10.4:1 until it reaches temp, does this mean the cold start of the map needs to be adjusted?
also when its had a bit of a boot it will idle at around 15.2:1.
Is any of that anything to worry about?
cheers

 

i run 12.5 on boost and i mapped the fuel out at some load sites light throttle at 70,80,90 mph so running 16's on cruise.my engine idles nowhere near stoich,it likes it richer at 13.5.I also leaned it out below 3000rpm on w.o.t to help with lag.

 

What ecu is it onand dose it have closed loop?

 

its on LINK and no closed loop

 

your cold start warm up is too rich Tiny
and your transient fuel correction requires some work for starters

 

Tiny the 19s etc when you back off are nothing to worry about if its only happening during deceleration

 

Tiny, sounds like nothing to urgently worry about, you probably would want to lean out the cold enrichment a bit though.

Mark Shead can map the link, so give him a bell

 

When you took some fuel out of your load site for cruise did you not see a rise in egt?
Im only asking as i tried this on my brothers zvh and after about half an hour of doing about 60-70 mph we pulled over and found the manifold glowing and we were only in the 14s afr so we richened back up to low 13s and all was fine for the rest of the journey apart from it using loads of fuel.

 

yeah it does hike the egt a bit but data logged at 800c so not worried,i nudge 900c on track,i have egt input into the my emerald and it has egt protection,I have melted an exhaust valve before years ago so its good to know it is protected.

 

my lamba is 10in from turbo is that ok

 

Yes that should be fine, just make sure there are no exhaust leaks before it.

 

I find if i go leaner than 15.3/.4 on cruise the car hesitates, so i try to stay around 14.7-15 on cruise...
Im currently low mid-low 13s at 5-7psi and high 12s at 12psi - too lean?
What i did find was turning the boost up to 14psi and making it 11s afr it felt slower than with 12psi at high 12s afr...

 

Obviously the leaner you run it the more power it will make

 

Only until you hit high 12s generally, once you are leaner than that the leaner the go the less power it will make.

 

True, you know what I meant though

 

Yes mate, but others who find this thread in future might not, so just making it clear.

Wasnt trying to imply you made a mistake or anything like that

 

It's ok Chip, I know you well enough by now