T-leg Piggyback ECU R&D

IronMonkeyL255 · Post by **IronMonkeyL255** » Tue Jun 21, 2005 6:15 pm

Here's a few:

http://www.turbo-link.com/tlink/details/3bars.html

http://racerwalsh.zoovy.com/product/AFMAF_16040749

towards the bottom:
http://www.turbobits.co.uk/acatalog/erl ... oller.html

These don't say they're the GM ones, but they ARE 3-bar.....
http://www.siastuning.com/ProdforSaleEngineSensors.htm

http://www.electromotive-inc.com/sensors.html

IronMonkeyL255 · Post by **IronMonkeyL255** » Tue Jun 21, 2005 6:22 pm

Here's an AEM 3.5 BAR sensor:

http://www.riderevolution.com/pc-422-19 ... r-kit.aspx

http://fasterthanthem.com/shop/product_ ... s_id/11349

Here's a 5 BAR sensor:
http://www.riderevolution.com/pc-423-19 ... r-kit.aspx

free5ty1e · Post by **free5ty1e** » Wed Jun 22, 2005 1:51 pm

Thanks for the links... I still have yet to find one at a lower cost (3 bar for $53) than on the first one I found.

So, it seems as though I can't get an automotive 3-bar MAP sensor that can take engine compartment heat for any less than $50. The Honeywell 0-30psi pressure sensor that I have here is not rated for underhood temps, but is only $30. I also already have the range calibrated and a PSI rapid lookup table filled in.

I have no problem running a boost line through my firewall, I already had to do that for my boost gauge. But I'd like to hear what you guys would like - is the extra cost of the GM 3 bar sensor plus the extra cost of the separate circuitboard we would have to make for remote sensor mounting worth it just to have the pressure reading 5-6 feet closer to the pressure source? The difference in signal response should be negligable with the small 5/32" tubing that fits the pressure sensor.

Update - got the new interface coded and tested. Overboost, partial boost, and TPS threshold adjustments are working. I've got an overboost toggle indicator, as well as a current boost situation readout (based on the overboost toggle and the tps voltage, am I in partial boost? full boost? over boost?). The peak boost hold now also shows a bargraph of where the peak boost was last.

Also found good, backlit, inexpensive LCD's. Can you believe that electroluminescent backlighting is cheaper now than LED backlighting?? Whatever. A blue or white EL display would look freakin' sweet on a product like this, so that's what I'm gonna get. You guys will have a choice of display backlight color, if you'd like to choose, and I can order the right LCD for you. I believe they have green, yellow, red, white, and blue. I'll show ya what the blue and white versions look like once I order some and get a chance to test 'em.

Hopefully today I will be hooking up the prototype in the car and running some tests (and some videos, if it works well enough!). If not, there's always tomorrow (although by then we should have the iPod karaoke production model back from the manufacturer for testing and debug so this project might get put on hold for a bit again...)

IronMonkeyL255 · Post by **IronMonkeyL255** » Wed Jun 22, 2005 2:14 pm

I wouldn't mind having the sensor on the board, myself. I can just tee off of my boost gauge line......

legacy92ej22t · Post by **legacy92ej22t** » Wed Jun 22, 2005 3:37 pm

Chris- When you say $100-200 range, is that for this EBC you're working on or for the LegaCU?

Something else to think about (you're probably already on it and its been covered in the Novel that is this thread) is that if you're using the OEM boost controller and/or MAP. The signals will still have to go to the OEM ECU or the car wont run right. If the ECU doesn't get the MAP signal it will cut fuel as soon as you go on boost, ect...

You probably already know this and I'm just repeating things already covered but I thought I'd throw it out there just in case.

free5ty1e · Post by **free5ty1e** » Wed Jun 22, 2005 4:59 pm

IronMonkey - exactly what I was thinking, most of us have a boost gauge already so why not just tee off of that?

Matt - Definately important to note, of course I will take care of that (as a matter of fact, if the resources are available I may just build in the FCD to the EBC. All I need is another analog output and a DAC to drive it)

Oh, when I say $100-$200 range, that's my estimate for what I can feasibly sell either product for. Either one will be at least $100 to cover parts and part shipping costs (for any hand-built product with a PSoC, good LCD, buttons, case, etc. -- not to mention the pressure sensor), and then it will require a bit of labor on my part to assemble, burn (program), and test each unit.

So - the EBC will most likely be $100-$200.

The LegaCU, although it will require MUCH more development effort and time, will sell for around the same price because once it's done I can reproduce the chips just as easily. Just be patient on this one.

Update: Just found an LCD that looks almost as good as the VFD I am using in the prototype - and for way less! The vaccuum-flourescent display sells for $160 (wow, glad I didn't pay for mine!), and the new black-masked white-LED backlight LCD costs $36! Score! (in higher quantities, they cost less, as do all parts - so when I start making more products they will get cheaper)

The new LCD is also a 4 line x 20 character display, same size as the VFD. So all the great information is still available at the same time. I could compromise with a 2-line, or even a half-width, but the display readings are no longer self-explanatory when theres no room for proper labeling. This is a great price for a 4-line display with a backlight like that.

Want a photo? I think I can do that...

IronMonkeyL255 · Post by **IronMonkeyL255** » Wed Jun 22, 2005 7:47 pm

Sweet.

free5ty1e · Post by **free5ty1e** » Fri Jun 24, 2005 1:35 am

Update: Prototype installed in car. Works great as digital boost gauge with peak hold. Also works great as a throttle position readout, and as a bonus, an airflow readout in CFM (neat to watch).

Spent the rest of the day learning that the solenoid was usually open, and only closed to regulate boost. The configuration displayed on Vikash's vaccuum diagram is correct, my tests in the garage were hooked up backwards. I had the valve normally closed, and then opened it to regulate the pressure. Live and learn

So I now have very loose closed-loop boost control. It oscillates 3 psi or so when regulating, so I now have adjustments to make to the chip firmware and some more tests to run in the car. I have lots of things to try for tighter regulation and in fact am very pleased to be at this point now where I have boost oscillations.

I think I will also keep track of peak airflow. I haven't been watching it too closely during the course of these experiments, but it seems so far that even at 6 psi on the TBird turbo, it's pumping out around 250 CFM in the midrange RPMs... I believe I will alter the interface to allow the viewing of an airflow bargraph instead of the peak boost bargraph if desired.

I'll get some photos tomorrow sometime, and post 'em up.

azn2nr · Post by **azn2nr** » Fri Jun 24, 2005 5:55 am

so this is for a ebc? not the legacu right???

when did this happen?

THAWA · Post by **THAWA** » Fri Jun 24, 2005 6:08 am

I believe this is part of the LegaCU. He's just testing bits of it at a time.

free5ty1e · Post by **free5ty1e** » Fri Jun 24, 2005 12:31 pm

Correct. If it can all be one product, it will be. If not, it won't be.

Gotta have tight boost control before I can try to tune for it...

(LegacEBC?)

free5ty1e · Post by **free5ty1e** » Sat Jun 25, 2005 7:07 pm

Vikash - did you ever find your Subaru Select Monitor code? I would imagine that I could try implementing the scan tool into the LegacEBC next.

I am very close to tight boost control, I've been running experiments constantly for the past two days learning the best way to do this empirically.

By the by, I was surprised to see a reading of 5.0 V from the MAF sensor. Does it read valid data above 4.5V, or does it read all the way to the rail? Because by my caclulations, that is 350CFM @ 85*F (which the t-bird compressor should be perfectly capable of doing, but it did it at somewhere between 12 and 15 psi...)

If it only reads valid conversions up to 4.5V or so, that means the highest valid reading I got was ~263 CFM or so. The values above that voltage are then invalid? It did indeed read all the way up at 5.0V and held a peak of 350CFM just this past run.

The airflow bargraph and readout is really cool. I like seeng that data in realtime.

vrg3 · Post by **vrg3** » Sun Jun 26, 2005 8:40 am

I still don't have the code... It's complicated by stuff going on in my personal life... I'll get it at some point though.

I believe the MAF sensor reads valid up to its internal +5v rail (which is independent of the ECU's +5v rail, actually).

Yeah, watching airflow in realtime is indeed cool. Also, try this -- multiply airflow in g/s by 5252 and divide by RPM and display it realtime as "estimated brake torque output." It's fun.

free5ty1e · Post by **free5ty1e** » Sun Jun 26, 2005 1:12 pm

Wow, reads all the way to the rail? So my reading of 5.0v @ 85*F was a valid 350CFM from my turbo? Kickass. I think I'll add another feature, when the MAF peaks I will have it grab the current boost reading (and RPM eventually, when I'm measuring that too) so it could be known what conditions smacked the rail.

No worries, V, personal complications are something I understand. I have plenty to do before I'll NEED your code in order to have something to do on this project

Estimated Brake Torque Output, huh? Neat... what would the units turn out to be in, or would they be arbitrary? I might just have to try that. Hell, I've still got half of the EEPROM free and empty, conversion tables are nothing to add (especially since I got off my ass and installed Matlab to help me generate said lookup tables).

Hey, I've got a question. Any idea what frequency PWM the boost solenoid should be controlled with? I'm stabbing in the dark here, and am about to make an in-car adjustment for the frequency so I can find out empirically... but anybody know what it should be? I suppose worst case I could get the oscilloscope untangled from my workbench and tote it outside to lock on the ECU's control signal, but thats more trouble than I want for now

Edit: It's been a while since I've put up a screen shot, so I'll go out to the car and get a few today.

vrg3 · Post by **vrg3** » Sun Jun 26, 2005 4:35 pm

Yes, I do believe it goes all the way to 5 volts. Realize that the sensor is powered by an external +12v source, so there's no reason it should be limited beyond the ECU's input range of 0 to 5 volts.

The ECU reports (via the Select Monitor port) a reading of 5.10 volts when the sensor is maxed out.

If you make the very very very rough assumption that one gram per second equals one horsepower, the units turn out to be ft-lbs. Unless you can't divide, it's probably not really worth even using a lookup table.

I think you probably want to cycle the boost control solenoid somewhere around 16 hertz. I don't remember exactly what the ECU cycles it at, but I've had success with 16 hertz.

I forget -- do you have it so you can log via RS232? Is that a planned feature?

free5ty1e · Post by **free5ty1e** » Sun Jun 26, 2005 5:09 pm

16 Hz... gotcha. I was experimenting with frequencies much too high.

The PSoC can divide and multiply just fine, it is just far more efficient to pull from a lookup table (and especially since I can generate lookup tables within 5-10 seconds with the assistance of Matlab). The current incarnation of the LegacEBC/LegaCU makes use of many such constant tables stored in EEPROM and still has over 16KB of room left.

Besides, this ensures that the product is as responsive as possible and not held back by the processor briefly dealing with floating-point values during certain divisions that need rounding.

Oh, and I don't have any logging set up but that is an eventual plan -- I can have multiple serial communication lines going at once (so one for a laptop datalogger / configuration interface and another for the Subaru Select Monitor, and even another if necessary).

Perhaps that'd be the next thing for me to work on once I'm happy with the boost control.

Still haven't been out of the garage, the FedEx package came yesterday with the karaoke accessory production boards, and we have some paid work to take care of again. May be a few days before I can work on the Legacy projects again.

vrg3 · Post by **vrg3** » Sun Jun 26, 2005 5:54 pm

Ah, cool... Yeah, I can see that precomputing is good in this case.

I think the laptop datalogger thing would be key. It's really nice to be able to take data logged from a drive and toss it into MATLAB so you can do whatever kind of analysis you like.

free5ty1e · Post by **free5ty1e** » Sun Jun 26, 2005 7:48 pm

I quite agree. Capital idea, that.

IronMonkeyL255 · Post by **IronMonkeyL255** » Sun Jul 03, 2005 7:35 pm

Bump.

Don't want this one getting too far down.....

free5ty1e · Post by **free5ty1e** » Mon Jul 04, 2005 12:43 am

Heh... thanks.

Got a chance to hook it back up and run some more experiments in the car today, the interface is really working out well. I'm getting close with the lower frequencies, but am still learning what works best here. Still only working on this in my free time, which hasn't been all to plentiful lately. But soon, I will be able to devote my full attention to it again.

azn2nr · Post by **azn2nr** » Mon Jul 04, 2005 2:33 am

saw the vid in the thawa gallery. lookin good

IronMonkeyL255 · Post by **IronMonkeyL255** » Mon Jul 04, 2005 3:47 am

I figured you were taking care of paid work, so that's why I wasn't buggin' ya for more info/updates.

I was just thinking.... It'd be pretty sweet to block up one of the center a/c vents and mount the display there. It'd be easily read by the passenger or driver, and wouldn't get in the way.

free5ty1e · Post by **free5ty1e** » Thu Jul 07, 2005 3:42 pm

OK - finally shipped the production firmware for my paid work... back to the boost control.

I've had some success with a closed-loop PWM-based system after I decided to implement an error calculation into the adjustments. It now oscillates only briefly when the desired boost level is reached, and then stabilizes at the right level. So I'm getting closer.

I have a vent mount kit already for my Pocket PC... so they exist and are available cheap somewhere. I don't think I'd want to mount mine there, but that may just be because that's where my GPS goes. Not only that, but if I didn't have a boost gauge I'd definately want to have this on or above the dash, in the gauge area for easy glance-viewing. But that may be an excellent alternative mount to offer. Couldn't hurt to have a source of universal A/C vent mounts.

I was toying with the idea of using inverse display characters to allow for high-visibility reflective and heads-up viewing. For example, by facing the display up in the right location behind the steering wheel would result in a reflection display overlaid on your speedo and tach gauges. Or, even better, with the right cowl configuration it could be reflected heads-up right on the windshield, where you should be looking anyway.

Edit: I realize this will require an LCD that is capable of displaying backwards text characters. Or I could just learn to read backwards

azn2nr · Post by **azn2nr** » Thu Jul 07, 2005 9:03 pm

as soon as you get this boost controler finished i want one.

IronMonkeyL255 · Post by **IronMonkeyL255** » Thu Jul 07, 2005 9:10 pm

I already have a boost gauge, which is why I suggested mounting it there.

It would be pretty trick to mount it as a heads-up display on the windshield.

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T-leg Piggyback ECU R&D