Hi

Just got my Stack AFR installed
Nice bit of kit, easy to install and fits nicely next to the SPA gauges

Im running closed loop from MSD on a T3 peaking at 2 bar
on idle I have 14,7 (sometimes it takes a little while to settle though)

on wot my AFR shows....10 , to me that is a "bit" rich - correct?

on cruise it fluctuates from 14,5 to 15,2 - very rapidly.

I would have thought that on cruise it should just settle close to 14,7 like it does when idling.

my CO screw on the ECU is centralized - so thinking of adjusting it to go a little leaner, and aim for about 11,5 AFR on WOT.

what do you think?

thanks

 

10 is rich

Cruise seems ok, as the lamda is constantly trying to keep it around that.

2bar on a T3 , i don't think it will last long

Steve

 

if its accurate that is alot rich, im only running 11.1 - 11.2 at 2.05 bar over 800 hp.

 

thanks

btw...2 bar, ALS and no Dumbvalve lol



thanks - I'll try and see if I can reach about 11.5

 

i dont know how you will alter wot fuel fella ?

 

Go and see a professional tuner for a set-up!!

 

I believe the CO screw is global adjustment - so turning it anti clockwise should make it leaner to my knowledge

keeping a close eye on the AFR naturally

correct my if im wrong

 

if your cruise fluctuates from 14.5-15.2, you really don't want to be making the whole range leaner.
otherwise you will compromise idle and off boost driving, what you do need to do is make sure the gauge is accurate and get it to a tuner.

 

The fluctuation is the closed loop control. You should speak to MSD, they may have set the ignition timing to match the current WOT fuel.

 

What is you're fuel pressure set to? what injectors?

 

it has to on closed loop control as the sensor is non linear and essentially is just a switch so that the ecu knows it's either rich or lean so it cycles around that point.

adjusting your global modifier will affect the whole range whilst out of closed loop (with attendant potential problems as already mentioned by Rick), but as you seem to understand already there should be enough adjustment available by the closed loop control for it to be able to stay under closed loop control around stoich at idle and cruise.

 

I've been there mate, and I'd just get someone to set it up

 

The stacks I have seen all show rich under boost, So I would guess its about right, Get it checked by someone has a good meter and not a cheap gauge.

Mark

 

my stack from rainbird showed 11.4 on my old msd mapped cossie, and it was mapped at 11.2 - 11.3 by stu, i remeber commenting at the time on how chuffed i was with how accurate it was compared to stus ŁŁŁŁ gear.

 

Would it make sense that a live mapped car would have some much nicer afr numbers compared to a of the shelf chip, wich I would believe would be made safe (obviously from the same company)

 

Thanks guys for input

Just a couple of comments and questions


very good point didn't think of that - but still 10....
unfortunately Stu is not in the office at the moment, so will have to wait til his back.

3 bar at idle as per Stus instructions, dark greens.
My fuel pressure peaks at 5,6 bar according to the SPA.

But why doesn't it cycle on idle? - it sits perfectly at 14,7

To my knowdledge I can go adjust +-25 on the IAW monitor and still maintain closed loop operation on cruise etc. as you also explain (1 turn in either direction is about +-15 on the IAW) I have actually tried going from the centralized CO screw to 1 turn leaner, and it made no difference to WOT that I could see.


Your not the first on this thread to suggest that. And although it does seem a good idea, I do feel that I should wait for the tuner who made the chip in the first place to clearify. Being an of the shelf chip, I did also make the choice to save some money and sacrify a little on the 100% perfect setup. I just find the readings a bit strange. Another issue is that, here in Denmark I wouldn't know who I would trust to make adjustment

In you mind, what is a good meter - for dashboard installation ?
I recall some high powered cars to run these - are they really that bad?

what I have thought, but didn't think it would be this much.


another aproach is that the chip is fine, but I have a fault somewhere.
What could cause this besides the chip being set to this
I mean what faults could cause this?
knowing that no sensor faults is shown on the IAW monitor.

thanks again

 

Lambda 0.68 (what you call 10:1 AFR) is filthy rich, the engine does not produces its full power potential and does not need much more to start misfiring. I'd also start to worry about cylinder washing.

Perhaps the tuner was not so sure about his ignition map and preferred to err on the safe side by dumping so much fuel, drowning some detonation in the process?

 

probably because the base map points around that area are so well mapped and close together that the inevitable averaging that you will get are masking it.

 

That's strange, I have compared the Stack gauge to our dyno DD AFR reader (Autronics make it for DD) and have found them to almost spot on (give or take .1), I did find that the reading was incorrect during warm up though.

 

I'm running the same chip by the looks of it, and remember reading the instructions that 25psi was max boost for it (2bar = 28-29psi).
I'd adjust CO screw to lean the WOT into the 11's, and idle should still be controlled by closed loop.
Just confirm with a garages CO meter that yours is about similar.

 

Martin you are using the Bosch sensor I guess, I am using the Ł500 NTK one on the meter and there is around .5afr diff between the two depending on the temp of the Bosch sensor.

Mark

 

Ł500 sensor, big ouch when that packs up !

 

If you want to trust the AFR you are seeing its a must, I prob average one ever 6 months depending on how much I use it.

Mark

 

So when your slating the Stack kit - you are actually slating the sensor from Bosch ?

genuine question here - not trying to be awkward

 

Yes its the sensor thats the problem, The only cheap meter I recomend is a NGK meter with the NTK sensor upgrade and not with the Bosch sensor,
The DD rr sensor is a diff bosch one also its not the same as the Stack sensor.

Mark

 

Nice. good to see you go to that extent when some tuners just rely on a Innovate poked up the tailpipe.

 

Do you have the part number for that Mark?? I may give it a try and see.

 

Its sold by Autronic for there meter so it comes through me,
You will be suppriesed how much faster the meter reads and changes afr compared to the bosch one, which I never use now due to the diff,
Autronic sells the Bosch sensor to cover 90% of your tuning needs but for the turbo cars we need the final 10% which is where the cost is,
You have to much more carefull with them over the bosch as you can damage them,
You would need to make sure your dyno has the model B meter as the up to about 5 years ago the dynos came with Model A meters and these only use the bosch.

Mark

 

Totally agree with Mark Shead. The Stack AFR 52mm gauge all seem to read around 0.5AFR too rich on boost, though they seem to to reasonably accurate around stoich. For example a true 11.5:1 will show up as 11.0:1 on the stack. The Stack gauge is an re-branded autometer item for those that did'nt know!

 

I reckon mine is an 'A' How the hell do you know??

 

I dont know as its badged DD when its got autronic on it this has the number on the front,
Speak to DD and ask them to check, or do you have another lead that has ntk o n it or the single lambda cable instead of your 2 connector bosch one.

Mark

 

Is this the one you mean Mark?

http://www.ngksparkplugs.com/product...rmance/afx.asp

 

Yes thats the right one.

Mark

 

Just wondering what the reason is that it is on boost that it should read wrong?

I mean how does the sensor "know" that the car is on boost.
How about a high reving NA engine - would that read correct?
does it make a difference if the boost is 1 bar or 2.5 bar?
what about the size of the turbo - does that influence the incorrect reading?
and what if the boost comes in lower revs compared to higher revs - is that still the same.

I am just mildly sceptical to the statement: "it reads 0.5 AFR rich on boost"

Is that just a very simplified explanation, or is there no more to it?

 

Temperature, perhaps. The NTK sensor is heated in closed-loop.

 

Probably just not correct at that point in the scale