The "let's brainstorm how to make a piggyback work" thread

[1nz]

well i was told it was for new car with relearning issue, so any one got the $ and just order it already hehe because when reading this thread i think diz is the right gadget all of u been looking for

[ChinoCharles]

Hi Charles

Thank you for sending us the specifications of your vehicle. We have managed to get a Toyota Yaris and we are going to do the installation next week. We would first like to see what the unit does on the vehicle and then we can take it from there and then talk about sending an unit out to you to try it out on your car. My manager is aware of this situation and would love to find a solution for you.

I will keep in touch and will definitely get back to you once we have done the installation and will let you know what the outcome was. What are the specification that you are after? Are you looking at fuel consumption, more power or timing?

Have a great weekend.

Kind Regards

Marcell Bruynius (Ms.)
Digital Data Systems (Pty) Ltd
Manufacturers of Perfect Power Automotive Systems
22 Arbeid Avenue, Strijdom Park, Randburg, Gauteng, South Africa, 2194
PO Box 35872, Northcliff, Gauteng, South Africa, 2115
Tel: +27 (0) 11 792 9805
Fax: +27 (0) 11 792 9818
Email: marcell@dtwebs.com
Website: www.perfectpower.com

Onwards!

[tk-421]

Originally Posted by ChinoCharles

Onwards![/left]
[/left]

That's great news indeed! Please specify "power" as a requirement!

[yaris-me]

I believe the AT and MT have different operating parameters. Will that have an affect on the piggyback?

[dallas]

Vey promising, your the Man! Good work,

Now let's hope and prey it's not one of those African scams !

Originally Posted by ChinoCharles

Onwards![/LEFT]
[/LEFT]

[eTiMaGo]

OK, here's my first draft:

Marcell,

Thanks very much for your enthusiasm!

The interest in tuning our cars' fueling is primarily for use with turbo/supercharger systems. But, if there s enough flexibility and results, I am sure may would be interested in tuning for better fuel economy too.

I will quickly outline the progress and attempts at working with piggybacks fuel management systems on various US Yarii.

Some years back there was a company, Zero Point Industries, which has since gone out of business, offering a turbo kit for the car, and using an e-manage unit for fuel management. They were unable to overcome the car's closed-loop logic for tuning, and their solution was to have the car in a permanent CEL condition, where the fueling runs in an open loop, and the e-manage can have control over it. As you know, this is an extremely crude approach!

Other members of our community have tried using AEM's FIC device which is supposed to work very well, but have had many problems, usually in closed-loop mode when then ECU is fighting hard to keep the AFR in stoich. I do not have more specific details at the moment but I can ask them to provide more information if you need.

On the other hand, we have a handful of members who are using a supercharger kit manufactured by Blitz, that comes with its own fuel management piggyback unit. Not a lot is known about its exact operation, but those members who have dyno'ed their car, or have a wideband O2 sensor, have found that it is still running rather lean, even at WOT when the car is supposed to run in open loop mode.

Now, one of these members is moving to a full standalone management system, but this is really out of the skill and budget of most enthusiasts who just want a reliable way to add 30-50 horsepower to their car.

We collectively have done a lot of research into the way Toyota set up the ECU to monitor the various sensors (MAF, IAT, AF, O2) to calculate the correct injector duty cycle, and it really is a rather tight-knit system, which is great if you do not intend to tweak anything, but too smart for our own good! We have access to rather detailed technical reference (repair/service manuals) describing all of this, so please let me know if you would like a copy. Alternatively, you can check the "brainstorming" thread in our forum:

http://www.yarisworld.com/forums/showthread.php?t=15350

Feel free to add/remove/modify

[eTiMaGo]

Originally Posted by yaris-me

I believe the AT and MT have different operating parameters. Will that have an affect on the piggyback?

The AT ECU is completely separate, and apart from the different idling speed, I don't believe there is any difference at all between the ECUs

[dallas]

Very well written, cant get more accurate and on topic than that

Originally Posted by eTiMaGo

OK, here's my first draft:



Feel free to add/remove/modify

[largeorangefont]

Sounds like you got some good feedback Charles. I would be open to testing and tuning something like this.

[eTiMaGo]

Well after some musing about this, there are two approaches to this whole fuelling debacle.

The first one is to try to tweak the closed loop operation to run richer on demand. This is rather difficult and would hinge on modification of the AF and O2 sensors to give the ECU the impression of running lean, causing it to make the AFR richer.

The second one, which according to Long's findings, seems to be the Blitz approach (and a far more refined version of ZPI's), is to just forget about closed loop operation and trigger open loop when extra richness is required. He noticed on his Scangauge that as soon as the SC clutch was engaged and producing boost, the ECU switched to open loop

Obviously the first method would be preferred, as it should keep the car completely OBD fault-free, so in theory have no problems with inspections.

Now, looking at the reference manuals, it seems there are 3 types of open loop modes (my comments in italics):

• OL (Open Loop): Has not yet satisfied conditions to go closed loop (i.e. warming up)
• OL DRIVE: Open loop due to driving conditions (fuel enrichment) (i.e. pedal to the metal)
• OL FAULT: Open loop due to detected system fault (i.e. CEL)

So Blitz's fuel controller would be triggering this OL DRIVE mode somehow. But how? I'll report back when I find more information

[eTiMaGo]

I'm looking again and again at the instructions and wiring diagram and the only input that the Blitz box has to the ECU is the MAF signal. So, the possibility is that OL DRIVE can be triggered by a MAF signal over a certain threshold. Long, does the SCII have any way to monitor MAF voltage?

[eTiMaGo]

back on the topic of the more elegant idea of closed loop tuning, URD has some rather interesting devices that could quite possibly solve this:

AFR Sensor calibrator:
http://www.urdusa.com/product_info.p..._id=1230100028
Tweaks the AF sensor's signal, thus affecting the short term fuel trim for closed loop mode

MAF sensor calibrator:
http://www.urdusa.com/product_info.p..._id=1260198051
A regular piggyback style device to tweak the MAF signal to affect the fueling in open loop

MAF + Timing calibrator:
http://www.urdusa.com/product_info.p..._id=1260198051
This ought to be enough to cover open loop operation where the timing is maxed out by default.

These products should be universal enough to work with our cars too but I am writing to them just in case, to see what input they may have

[eTiMaGo]

Thanks Pavel, some good info there... do you mind if I post the excel file here in case anyone wants to have a look at it?

[eTiMaGo]

well here's PK's data log of a drive in various conditions... mostly gentle driving, and you'll see several apparently random points where it goes to open loop, but looking carefully you'll see that it corresponds to the car slowing down and minimum throttle.. thus, DFCO!

can't attach excel files here, but here's a download link:

http://dl.getdropbox.com/u/691356/Normal%20Run.xls

[largeorangefont]

Why do you guys want to do closed loop fueling adjustments? They are not needed. The car is self adjusting (to a point) in closed loop.

[eTiMaGo]

Originally Posted by largeorangefont

Why do you guys want to do closed loop fueling adjustments? They are not needed. The car is self adjusting (to a point) in closed loop.

well yes but it tries to stay at 14.7 AFR no matter what. And from looking at the data that Pavel posted, the car can stay in closed loop mode even up to quite high RPMs, as long as the gas pedal is not being mashed down.

On the other hand, it is something I am not so sure about in the first place, at three quarters throttle, 4000RPM, for example, is there enough pressure from a SC/turbo that it would require fuel enrichment? Or am I barking up the wrong tree?

[eTiMaGo]

Pavel's newest run, equipped with a heavier foot:

http://dl.getdropbox.com/u/691356/1to3Run.xls

note the relation between throttle % and open loop in the initial acceleration phase. Red numbers are shift points (hence the spot of 20% throttle which could be ignored)

[largeorangefont]

Originally Posted by eTiMaGo

well yes but it tries to stay at 14.7 AFR no matter what. And from looking at the data that Pavel posted, the car can stay in closed loop mode even up to quite high RPMs, as long as the gas pedal is not being mashed down.

On the other hand, it is something I am not so sure about in the first place, at three quarters throttle, 4000RPM, for example, is there enough pressure from a SC/turbo that it would require fuel enrichment? Or am I barking up the wrong tree?

That log has great info, but he is just putting around. Have him datalog a pull in a gear. Do one in 2nd from 2000 RPM and full throttle to redline, and the same in third gear. What is done to the car?

You are thinking correctly. Generally forced induction cars go into open loop sooner than NA cars. Some NA cars don't hit open loop until you go WOT. My guess is that this is one reason the Blitz SC is clutch driven, so you are not getting boost at lower load areas.

We can't see the actual AFR, but we can see his timing, which will be helpful.
Can he graph injector latency or duty cycle too? If so get that on there.

You can't hope to tune closed loop, no piggyback I have ever seen can do it. It just causes problems.