Motec-wide band lambda control

I did that with my last haltech, that is just closed loop operation. I set the base maps about 3% rich then gave the lambda a +/-8% range. Then if the sensor fails you go just a tad rich.

The way the haltch worked, it wanted a % throttle position to diengage cloped loop, I picked 20% and it seemed to work well. A lambda of 1 is full scale, the will never take action at that setting, it sounds like that is how motec sets the limit. A lambda of .600-.700 is 14.7 a/f of most sensors, .88 should be about 13:1, a good number at full power.

 

Hi Peter,
It's good to see your posting.
I did the Motec training you can download from the motec site. I believe that in the tutorial motec expains that the theoretical optimum mix of 14.7/1 is referenced as a value of 1. therefore, your setting of .88 is 88% of optimum. The numbers you state sound similiar to those on my turbo maps.
I could be wrong about this, I don't think so.
My trubo car has been running wide band lambda for over a year, no problems at all. My M48 pro box has been great.
Jeff

 

Hey guys, Just a quick thought on Lambda. That is what the bosch manuals say too. The that 14.7/1 is the optimum for fuel econ. and polution control, though not necessarily for best power because that mixture ratio is more on the lean side. Regards, Vern

 

hmmm, clearly the numbers mean something very different on a motec, sorry to give mis-information.

 

OK, you've opened pandora's box now.

Closed loop lambda control is an option that many aftermarket ECU's have. Unfortunately, very very few accomplish this in even a competent manner. The one's that do are above even Motec level. For that manner very few OE ECU's are good at it. Most only use it to trim the idle or constant cruise mode and switch to open loop whenever the car accelerates or is anywhere past 50% load. Also, the only way I would trust a closed loop system is if it used the NGK UEGO type or the Bosch LSU4.2 (under sufferance). I can't comment on the LSU4.9 as we haven't seen enough of it yet.

14.7 (or lambda) is NOT optimal. That is far too simplistic. It IS the stoichimetric ratio at which the kind of hydrocarbon's you find in petrol react with the atmosphere. It is fine (most of the time) for idle and cruise. But try running your 355 on lambda 1 (or 14.7:1 AFR) and you'll have a box full of melted pistons on your hands..........

If you must tool around with closed loop, make sure your lambda's are new (ish) and preferably the type I mentioned above. It's fine to run at 14.7 at idle but you want to be down around 12.5 to 13 under full load (i.e. 100% throttle or 100KPA map).

 

didn't mean to say 14.7 to one was "best". In fact I think there isn't a cell on my maps that has the car that lean.

 

For the catalyst to work, you need to cycle equal amounts rich/lean...

 

That is what I meant also, 14.7 mixture is what "street" car manufacturers want/need an engine to run at at operating temp. Also to stay at when the engine is at idle or part throttle to pass emissions. As was said above it is the mixture that produces the least amount crap that goes into the air. 14.7 definitely isn't going to work at WOT, sorry I guess I thought that was assummed by the above reference to his 13:1 mixture statement above. Regards, Vern

 

Yeah, I had to say something as it read a bit differently to what you meant.

BTW, the motec course doesn't actually teach you how to tune a car.

 

FWIW my dyno testing has shown 13.2-13.5 to be the ideal AFR for max power, based on literally 100's of runs i.e. a lambda of 0.9-0.92. An AFR of 12.5-12.8 is the target value for most well sorted turbo/supercharged applications, not naturally aspirated. You will lose at least 3-5% power running a NA motor at these numbers IMO.

 

I'll take a stab at the explanation but "efioz" probably can do better than I can, closed loop is the term used for the engine operation after the engine reaches its manufacturer set operational temp lets say 190F. At closed loop the O2 sensor is the main sensor that the ECU uses to contol the fuel "trim". Usaually set at 14.7 at idle and part throttle. Not the most thorough definition but hope that helps. Regards, Vern

 

Closed loop is where the ECU uses the O2 sensor readings to change the fuel mixture, to meet a predetermined lambda value. I don't know how Motec works, but I would be looking for a closed loop where you can write a target lamda trim value based on throttle position/load.
The problem with closed loop operation is that it is "correcting" AFTER the fact, rather than in anticipation of what the motor requirements are going to be.
My limited understanding, based soley on a telephone conversation with a specialist, when discussing converting my race bike to Motec, is that you can use closed loop operation to write a basic map, that you fine tune manually afterwards.

 

Myself, the NACA, Ben Strader and most engine builders of note respectfully disagree with you on this. It is a little, but long known fact that AFR has little to do with absolute engine power. Yes, there is a point that an engine will make less, but in reality that AFR number could be anywhere from 11.5 to 14 an make as little as 2% difference. AFR is a matter of internal thermal management. And I would not recommend running a turbo leaner than 12.5, either.

There are other's around that have software capable of fuel mapping automatically using a wideband lambda and some trick software. It's usually done under controlled circumstances but it cuts a lot of time out of mapping.

Vern's right. Closed loop can also refer to any control system like boost control or knock control as well. It just means that the ECU uses a sensor to determine whether a parameter is within it's limits. If it's not it corrects until it is. This is essentially what lambda control is. Stephens is also very right in saying that it also happens "after the fact". If you want to correct for varying environmental conditions, then properly calibrated correction tables are the way to go. This way the ECU know's how much to correct for before it even does anything.

 

You are asking basic questions that unless you have a full understanding with years experience tuning not only on a dyno but in real world conditions you should not be messing with your map.

I've fixed more blown up engines due to bad maps from folks that get over their head.

It has taken me "years" of experience tuning Motec, Haltec, EFI, Zytec, Bosch, etc. to be where I'm at now......but it all started by understanding basic fuel and timing needs for a given engine.

If you would like some professional help, contact your Motec dealer. For Texas I am a dealer/installer (David Moore, Moorespeed as is James Patterson Norwood Performance as is Sam Shalala Protechnic. Contact info can be found on the Motec site at dealer info.

Since you are in Australia, the home of Motec, you should contact them direct and they can point you to the right "Ferrari" specific experienced Motec dealer.

There is a lot more to just the base maps and you need to be VERY careful. For one thing, the Lambda table did not come that way from Motec, it was programmed too.

BTW, 0.88 lambda is optimum for power under load in most normally aspirated air cooled engines. It can be up to 0.91 on some water cooled engines and as rich as 0.83 on high boost turbo engines.............it's not a general constant. This is due in great part as stated by others managing thermal issues. You can make a ton of power on for a few seconds and blow it sky high at that very reading if you can't control heat. This is one reason why turbos take more fuel as do air cooled over water cooled.

Just hate to see someone else spend tens of thousands of dollars learning the hard way.

D

 

Patrick

IMO if you are running max power at 11.5-12 to 1 it's because it is probably a forced induction application AND you are running too much advance for the quality of fuel you are running, therefore you are using the excess fuel to cool the cylinder to stave off detonation, or are not controlling intake temps sufficiently through bad charge/intercooler design. If max power is at 14.0 to 1 you are running too little compression or not enough ignition advance for the fuel you are using. So in the spirit of clarification, I would restate my original post by saying that;
Given optimal compression (both static and dynamic) maximum power is generally found with an AFR of between 13.2 and 13.5 to 1 on a naturally aspirated motor with good basic design (fuel disribution particularly) in a street motor.
My experience has shown that leaner mixes do not neccesarily effect power output greatly, but with greater risk of engine damage, whilst power drops off considerably as soon as you dip into the 12's. Additionally some combustion chamber designs are more sensitive to this than others. With supercharged motors, I have found 12.6-12.8 to be the target full load/WOT number, but the key is getting the intake temp as close to ambient as possible. To my mind, your statement about thermal management is a euphemism for using the AFR to correct bad basic design/setup.
BTW I have been writing my own maps for many years now, without being in the business and have yet to blow up a motor, but have also done more tuning runs than most of the "experts" that I have come across.
It never ceases to amaze me the lack of understanding some "dyno tuning" operators actually have regarding both the theory and practical componants of their profession. - Patrcik this stament is not aimed at you, as I do not know you or your skills/experience personally.

 

Patrick
O/T, but how does the EFI Race 4.0 compare to the Motec, pricewise?

 

interesting discussion. Not much I can contribute, other than a few settings..

360 standard road car = lambda 0.80 = 11.76:1 at full throttle.
360 N-GT = lambda 0.888 = 13.05:1, but they have a richer map option to maintain combustion chamber cooling for endurance racing, but I haven't read it's WOT value so cannot say how much richer.

From testing and observation, air intake temperature reduction is critical to maintain performance.

 

You've actually agreed with me in that post but I don't think you realise how you've done it. My position is this, you can make good HP at all sorts of AFR's, it just depends on how long you'll do it for. I do stand by my statement that AFR has little real effect on power production. The excess fuel factor is not where your powers coming from, it's what's keeping the engine alive (and more importantly the chamber out of the auto ignition zone) that's the important part. I do a graphic demo of this in my classes where we take an engine from 12:1 (or until it starts to misfire) all the way to 15:1 (or until it starts to lean misfire) at a steady RPM, observing tractive effort as we go. I've yet to see a subject engine that varied more than 1-2% (whilst it wasn't misfiring.

A quick question, have you ever truly back to backed AFR's? And if so, how did you do it?

 

From my limited observation of dyno operation (I HATE Dyno's BTW), it would seem to me that many variables in the AFR sample are possible.

A sensor shoved 30cm (or less I've seen) up the tail pipe will NEVER read the same as a sensor fitted to the collector (like all OE sensors are). You get reversion and air leaks taking effect.

For me, I've yet to see a better method than spark plug colour. It's slow, but accurate.

 

Were's Joe (JoTeC) this stuff is his specialty.

 

Smarty pants, tricked me into agreeing with you!!
Seriously, though I agree with you up until about 75% of peak hp rpm. I have found that power at peak HP/rpm particularly is greatest effected by AFR. ie this is the difference between a motor that holds power after peak power/rpm and a motor that falls on it's face as soon as peak hp/rpm are reached.
I have done several hundred back to back AFR runs on both Dynojet and DynoDynamics chassis dyno's. I have long learned proper techniques for ensuring repeatability of results, which most local dyno operators seem to be oblivious too.
My predominant experience has been on a Ducati race bike, which I could vary from 135-160hp @rw by varying the AFR between 12.0 and 13.4 to 1, with optimised timing. This is an extreme example and just shows how sensitive some motors can be. I remember Phil Tainton at the time remarking that he had never seen a motor so sensitive to AFR before.
On the supercharged benz power varied between 350kw and 380kw @rw between 12.0 and 12.8 to 1 AFR, but required quadrupling the capacity of the charge cooler system, which resulted in a 50rwkw gain in it's own right.
My Ferrari which standard runs 12.2 to 1 at full load and WOT increased power by almost 20kw at the rear wheel when an O2 sensor shorted and took the AFR to 12.9-13.0.
Changes to AFR have been affected by either piggyback ECU, Eprom emulator/writing software for Bosch ECU's and programmable ECU's.
My experience with performance "street" motors and motorbikes has shown that there is less sensitivity to ignition advance than fuel mix, given that intake/combustion temperatures are sufficiently controlled.