How are you calibrating / adjusting for water injection AFR?

[Sato]

Originally Posted by turboICE

An EGT reading will tell you that you are in a dangerous state - but it doesn't tell you why. It could be timing or fuel ratio.

AFR readings from anything other than a wide band lambda sensor is pretty much uselsess. When people talk about monitoring AFR for engine tune - it should be with a calibrated wide band limbda sensor.

A wide band lamda sensor measures partial pressures in the exhaust to interpret the components of your induction charge. Unlike O2 sensors which are only accurate around a very narrow range near stoic a good wide band lambda can provide you with your AFR from 10:1 to leaner than 20:1 - if it has been calibrated for your fuel inputs (i.e. gasoline, methanol, propane, etc.) and has been calibrated for any water injection rate (since water injection dilutes the partial pressures and apparently tends to cause readings closer to stoich than truly exist).

In knock limited tuning situations, most setups have known AFR limits. For instance a given engine may run fine at 20psi and 11.25 AFR at MBT with 93 octane, but need to be at 11.00 AFR with 91 octane and 10.50 AFR with 89 octane. This is why many prefer to tune by AFR - the target is known from many uses. Once you are at the target AFR the tuner is able to tune to MBT. This becomes the "preferrred" tuning and monitoring tool for tuners that want to run at MBT and use fueling levels to suppress knock.

Yes if you run past MBT you will get knock at appropriate AFR levels even rich AFR levels.

With water injection and other knock suppressing technologies AFR no longer becomes a target - but a result. Without knock limits you can tune for maximum AFR power - using either a dyno or cylinder pressures. Then you can advance from there to MBT.

There is no single best monitoring tool. EGT is a quick check if everything is OK, but will not tell you what exactly is out of tune fuel or timing. AFR is good only if you know what your AFR is supposed to be for the components your charge mixture in the cylinder (including correct octane) and the sensor is calibrated for your charge mixtures. To the extent possible good quality knock monitoring with timing retard will protect your engine - but does not necessarily resolve a bad tune.

I understand now . Thanks for the info but how do you find one,buy one and have it calibrated?[lamda sensor] What info do you need from the car? How much is this sensor?
Like you said I refer to my stock O2 sensor last after EGT's and a scanner for knock. I let the knock sensor with timing retard in my computer be the safety valve and never pull timing in any of my attemps at tuning.
Looks like I have much to learn about this!
Sato

[Sato]

Originally Posted by Philip

Hi all,
the trouble with knock detection is if your engine hasnt got a system on it, like mine hasn't, then i think its very difficult to detect as the after-market systems Ive heard of are a compromise, so im led to beleive. I did hear of a chap who recommended making a tube with a horn type of arangement on the top and bolting that to the cylinder head to amplify any noises, but thats a bit impractical in my mind,
Phil

I don't know if you're interested or not but J&S Electronics makes a very good stand alone knock retard system. I had used one for a race computer that did not use a knock sensor at all. It will pull timing on all cylinders at once or individually. You can program it to pull timing at different rates at the sign of knock. It also has a guage that will tell you if knock is detected and how much timing is being pulled and from what cylinder. Since it's stand alone it can be used on any car with or without computers. It costs about 450 dollars or so. I have heard of them on Ebay for 200.
Sato

[Forum Admin]

There are many places that sell wide band lambda sensors.

My prefered ones because they work as well as high end ones are the one that was developed from a DIY board and is sold by Tech Edge:

http://www.techedge.com.au/vehicle/wbo2/default.htm

And the new one from Innovate that just won the best new product at SEMA:

http://www.innovatemotorsports.com/

Innovate has a mailing list on their product and would be a good place to ask questions about AFR and lambda readings and how to use them as a tuning tool.

http://autos.groups.yahoo.com/group/InnovateLM1/

[Brad]

The DAK1 from Mechtech is what I use. Lots of things can be recorded at one time. www.mechtech-ms.com/html/dak.html
Wide band O2, boost, EGT(4 if you want) air temps, oil temps, throttle position, MAP sensor output and a lot more if you get creative.
I have recorded 30 minutes at a time the only limit is the size of your labtop computor.
By recording so many things at one time you get a true picture of what is going on and why.

[Philip]

Brad,
I use the DIY-WB (NTK Sensor) it works very well but only gives 0-5V signal out, but the Megasquirt ecu it feeds then gives me the facility to monitor and log all the sensors you talked about. Cost me under ?300 for everything.

Sato,
I would be interested in a knock detection system, even if it were for the future, any idea if they have a website?

thanks
Phil

[Sato]

Originally Posted by Philip

Sato,
I would be interested in a knock detection system, even if it were for the future, any idea if they have a website?

thanks
Phil

Here's the website. This guy used to work for Hughs aircraft electronics I believe before starting his own company.
Sato
J&S electronics in CA
www.jandssafeguard.com

[Brad]

Philip,
My data logger is moved from car to car. It has tuned 10 different cars the the last 6 months, but I am going to check into the WD O2

[Philip]

Brad,
that sounds like a good system, couldnt change mine between cars due to it being a function of the ecu. This is a link to the WB I use, its probably the least useable type about as it only has the output coming from it, no programmable stuff on it, but it is cheap and it works, just depends what you want and how much your willing to spend,
Phil
http://www.diy-wb.com/

[pbonsalb]

Consider a knock monitor. There is an inexpensive kit out there that works well on cars equipped with knock sensors and that can be tuned for ones that do not have them. I have one and it works well. It cannot retard like the well respected J&S Safeguard, but it is much cheaper and will alert you to knock via an LED.

http://www3.sympatico.ca/borism/

Philip Bradley

[Philip]

I have looked into that one, but surely youve got to make the engine knock so you can tune it for the knock or do you just tune it onto the edge of triggering when engine running without knock?
Just thinking I could add the input into my ecu, write a bit of code that would retard ignition by a fixed amount if knock detected, I do have the MSD 6BTM unit as well that I can dial in retard against boost, so if light still on I could then dial in some more, worth thinking about I think. Might order one after Xmas and have a play,
thanks,
Phil