[rusEfi] 1991 Honda CRX B16A Swap #32

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ZHoob2004
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1991 Honda CRX B16A Swap #32

Post by ZHoob2004 »

I'm starting a project with converting my B16A (obd0) swapped CRX to rusEFI. As I understand (correct me if I'm wrong), the setup should be very similar to the obd1 accord and preludes that have been documented here so far with the exception of the ecu connector (solved with $20 jumper harness) and the number of teeth on the crank trigger wheel (16 vs 24).

I'm currently in the process of gathering all the components I need such as the aforementioned jumper harness as well as the rusEFI ecu itself but I hope to be up and tuning within the next few weeks and I'll try and document my progress (or lack therof) here.
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Re: 1991 Honda CRX B16A Swap

Post by kb1gtt »

Welcome along, and sounds like an interesting project.

Jumper harness sounds like a good approach. I don't know much about prelude vs accord, perhaps there are others here that can comment. I'm sure that rusEFI can do it, I just don't know how similar they are. Do you have a schematic for your existing setup? Trigger wheel hasn't been a problem. If a wheel decoder exists, you'd just have to configure it. If a wheel decoder doesn't exist generally you would need to get the crank pattern to russian, then he'd make a decoder for that wheel. Of course if you are software oriented, you can also make the wheel decoder, which is handy as russian's software resources are time limited. He's done it many times, and it seems to happen reasonably fast once he's got the pattern. He used a very flexible decoder algorithm. So from a planning stand point, I would say don't worry to much about if a wheel decoder exists or not, if it's a problem, it would be a small obstacle. I would focus more on if you can get the physical inputs and outputs connected.

Does the engine currently run? If so you might want to consider the migration board. It allows you to move wires one at a time, incrementally migrating over to the new system.
http://rusefi.com/forum/viewtopic.php?f=4&t=454
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Re: 1991 Honda CRX B16A Swap

Post by ZHoob2004 »

AFAIK Prelude and Accord both came with either F series or H series (for 4 cylinders) and both families of engine are very similar. Both vehicles as well as 92-95 Civics use the same connector pinouts, and share the same physical connectors as the OBD1 Mazda connector on the frankenso.

Currently the engine is running pretty well on the stock Honda PW0 ECU with an A'PEXI VAFC piggybacked on. The VAFC came on the car when I got it and I haven't bothered to remove it (will be removed or disabled before switching).

Now for some progress:

I'm currently going through the pinout on the frankenso wiki page and comparing it to the factory Honda pinout. While it would probably be super easy to just rearrange the jumper harness, A goal of mine is to do all rewiring on the ecu side so it's truly plug and play.

This brings me to a question: By default, injector wiring is as follows (using Honda pin numbers)
Image
out - phys - pin
INJ1 - A3 - PB9
INJ2 - A6 - PE2
INJ3 - A1 - PB8
INJ4 - A2 - PB7

Can I simply remap these (with the exception of maybe inj3) in software so that INJ1=PB8, INJ2=PB9, INJ3=?, INJ4=PB7?

On a final note, I'm not too keen on the migration board but we'll see if I have to go that route anyway.
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Re: 1991 Honda CRX B16A Swap

Post by kb1gtt »

Same physical connector you say, yes you have lots of re-mapping options. If your existing harness has an injector on a particular pin, and if that pin is a rusEFI low side injector driver, you can make that injector driver what ever number you want. It could be 1, or 4, or other. That's software configurable.

If your OEM harness happens to land an injector on a pin that's an analog input or something that's not an injector, you can remove the W## jumper, and install a jumper wire inside the ECU which allows you to re-map that pin. For example, see jumper wires for this honda. You can see several circuits were re-wired from the left side of the harness, to the right side of the PCB.
Image

The long term plan is to have these boards that get installed there such that you don't have a rats nest of wires, but for now you can re-map the internal connector by installing jumper wires.

So your first line of flexibility is software configurable, if that doesn't work you can make changes in hardware.
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Re: 1991 Honda CRX B16A Swap

Post by ZHoob2004 »

Alright, that's just as I thought then. Now related to that, I've done some searching but can't find is there a complete diagram of the frankenso pinout with generic labels somewhere? I can only find the one with the Miata NA pin labels.
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Re: 1991 Honda CRX B16A Swap

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Re: 1991 Honda CRX B16A Swap

Post by ZHoob2004 »

Now I feel dumb for not seeing the giant pin diagram above the one I was looking at...

As far as soldering, I've done some work with surface mount projects (DACs mostly) so I'm not entirely new but I'll admit I have no experience with solder paste and reflow so we'll see how that goes.

I suppose now I can really get to work figuring out how many wires I'll need to run and how many can be done in software.

On another note, the honda distributors have 3 vr sensors, and the frankenso has 2 vr inputs. I understand there is a way to get another vr input out of opamp inputs, but is there firmware support for this? I want to say this only impacts starting but if it's possible I'd like to try it.
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Re: 1991 Honda CRX B16A Swap

Post by AndreyB »

ZHoob2004 wrote:I'll admit I have no experience with solder paste and reflow so we'll see how that goes.
I use this paste with cheapest hot air gun and sometimes even with a soldering iron.

ZHoob2004 wrote:honda distributors have 3 vr sensors, and the frankenso has 2 vr inputs. I understand there is a way to get another vr input out of opamp inputs, but is there firmware support for this? I want to say this only impacts starting but if it's possible I'd like to try it.
I'd suggest going with two channels to begin with, but later you can add an add-on board to get more channels and the firmware does support three channels in theory - in reality no one has used three channels so far.
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Re: 1991 Honda CRX B16A Swap

Post by AndreyB »

PS: your kit is in the mail box already.
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Re: 1991 Honda CRX B16A Swap

Post by kb1gtt »

Perhaps broken link above, I have used this paste before, comes in a nice syringe http://kd5ssj.com/solderpaste
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Re: 1991 Honda CRX B16A Swap

Post by ZHoob2004 »

Board arrived Wednesday. Since then, I've completed the power supply as well as soldered a lot of the main ICs. PSU tests good on my "12V" wall wart so it shouldn't be a concern.

Does anyone have some hi-res pics of an assembled 0.4 board? I'm running into some questions about chip orientation that I could easily answer with some reference pics.
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Re: 1991 Honda CRX B16A Swap

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Re: 1991 Honda CRX B16A Swap

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Re: 1991 Honda CRX B16A Swap

Post by ZHoob2004 »

I was using the first set already (as well as the .1/.2 where applicable). Those last 2 are what I was looking for.
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Re: 1991 Honda CRX B16A Swap

Post by ZHoob2004 »

I haven't made any updates for a while, but I AM working on it still (just not as fervently). Up to this point I have done basically everything except figure out the resistor values I need for the Honda sensors (russian, maybe you have these already?), the jumpers I'll need to set up on the harness connector, and attaching the harness connector itself.

I did a plug-in test with the brainboard and my half finished ecu and started to lose a bit of smoke out of the brainboard USB power supply. After unplugging, I fond I had the op-amps backwards and after fixing that everything works and I get to keep the rest of the smoke. LCD connector is also installed (I went ahead and set it up with removable pin headers) but I can't get it to work yet, so I must be missing something.
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Re: 1991 Honda CRX B16A Swap

Post by AndreyB »

https://svn.code.sf.net/p/rusefi/code/trunk/firmware/config/engines/honda_accord.cpp says stock resistors are 1.5K at least on my old Accord

Did you flash rusEfi firmware/install drivers/connect with TS or rusEfi console yet? What is the exact issue with the LCD - does the backlight work?
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Re: 1991 Honda CRX B16A Swap

Post by ZHoob2004 »

Flashed firmware with console, that all seems to be working well. I don't have the usb ttl finished yet so I can't test console+TS yet, but they seem to both work individually. LCD has backlight when I jumper the power, but no text (is there a different firmware I need for LCD?). I'm powering the whole setup off a "12v" 1A power supply from an old modem (actually runs about 15v, so it's a good analogue).

Accord values should work just fine, I've never heard of having to change sensors when converting to obd1 so I'm pretty sure they're exactly the same.
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Re: 1991 Honda CRX B16A Swap

Post by AndreyB »

Default firmware as is should display some text. Do you have the contrast resistor soldered? I believe it's on the back of the board.

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Re: 1991 Honda CRX B16A Swap

Post by ZHoob2004 »

Looks like the contrast resistor is at fault after all. I thought I saw r99 on the front of the board by the crystal but I can see now that I was mistaken. I don't think rv101 comes in the kit, is it necessary to populate, or is there a way I can bypass/substitute some ordinary resistors? (or is it even needed at all?)
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Re: 1991 Honda CRX B16A Swap

Post by AndreyB »

Right, I should probably add the rv101 into the kit!

Depending on the screen the value you need is usually between 1k and 2.5k, be sure to test this while on your current +12 power supply and not while feeding the board via USB since the screen gets less juice this way.
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Re: 1991 Honda CRX B16A Swap

Post by kb1gtt »

If you know the value for the RV1001, you could install a SM0805 or thru hole resistor in W101. Or if you know the total resistance, you can install a jumper in W101, and install a different resistor for R99. Basically you need to get a specific resistance between the VLCD pin and GND. The RV1001 is because we have seen variations in this resistance from one MFG to the next. We have seen it often need at least 1K and I think we have seen it need up to 2K. You can get that resistance any way you like, as long as the total resistance is what it wants.

Also I believe this resistance may need to change with wide temperature swings, so you might want a POT just so you can adjust it on track day, if it has wondered due to hot temperatures.
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Re: 1991 Honda CRX B16A Swap

Post by ZHoob2004 »

I don't have the circuit in front of me, is that 1-2k total (including r99) or 1-2k in addition to r99 or is it a divider that needs 1-2k on the other leg?
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Re: 1991 Honda CRX B16A Swap

Post by AndreyB »

Not a divider for sure. Is not one of them just a 0R?
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Re: 1991 Honda CRX B16A Swap

Post by kb1gtt »

It's 1k to 2k total, so the R99 1k is the expected minimum, which protects the POT if you crank the pot down to 0R, and it's 2k if you crank the pot to the full 1k side.
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Re: 1991 Honda CRX B16A Swap

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I suppose I'll tack a 500 then and see how it goes. I'll try to err on the side of too little resistance since the resistance should increase with heat, right?
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Re: 1991 Honda CRX B16A Swap

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Stuck a 0R in W101 and ran without RV101 and the LCD is working well enough for me. I also installed a pin header and an extra-long pc jumper I found in my things to enable/disable lcd power. I may also put some of these on the high-side drivers because why not?
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Re: 1991 Honda CRX B16A Swap

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The heat related contrast thing was something some random person claimed in a forum post that I once read many moons ago. I've not tested it and have no idea how the resistance might change, or if it will actually change. From memory, I seem to recall it was an Arduino project, and they added a temp sensor such that they could adjust a low pass filtered PWM, that was used to digitally control the contrast. So they didn't happen to mention if it went up or down as the temperature changed. I seem to recall you would toss it in your freezer, adjust the LCD contrast via up and down button then press a button, it would save this calibration point. Then you would get it hot, and do the same thing. I seem to recall hot and cold was all that was needed, but you could technically add more calibration points if you wanted. I think the implication was that this tendency would likely vary from MFG to MFG, and it may or may not be linear.

Good to hear you have it working good enough.
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Re: 1991 Honda CRX B16A Swap

Post by ZHoob2004 »

It's been a while since I've done anything on the ECU, and I think it's about time I finished it. It's been sitting nearly finished since I last posed in April, and I'm tired of having it around and not doing anything. No promises of it happening in the next few weeks, school still will have to come first, but it's definitely possible.

Now, the reason I'm back here without a complete unit is I have a question about C103/C104. I'm wiring up the board for VR, since that's what Honda used in the distributor, and I've found that I don't have any 10uf capacitors for C103, the largest I have is a 1uf. Is this an acceptable substitute, or does it absolutely have to be 10uf?

Also all the other resistors in the crank/cam section are listed as 5k, I assume 4k7 is what I actually use?
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Re: 1991 Honda CRX B16A Swap

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The 10uF is what the factory datasheet suggests. Other sizes may work, but have not been tested and are a bit of an unknown. I really do not know what these caps do. They are simply what the MFG suggests. It seems to be part of a filter. Snippet below from the MFG datasheet.
Input Bias 2. Connect to an external resistor-divider and bypass to ground with a 0.1µF and 10µF capacitor.
Frankenso uses 4.99kohm resistors. Those are reasonably available.
http://www.digikey.com/product-detail/en/RNCP0805FTD4K99/RNCP0805FTD4K99CT-ND/2240591?curr=usd&WT.z_cid=ref_octopart_dkc_buynow&site=us
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Re: 1991 Honda CRX B16A Swap

Post by ZHoob2004 »

I'm still alive and even have updates! I've got the unit mostly complete (I've skipped a few nice to have features and made a few compromises that might haunt me) and I'm at the point of plugging it in and cranking (well, I did plug it in and blew a fuse because a pinout I found on the internet was wrong...)

Anyway, I have a question first: I understand my stock obd0 Honda distributor to have 3 vr sensors with different wheels - 16, 4, and 1 respectively. Since no teeth are skipped on the 16 and 4 tooth wheels, my intuition is to use the 16 for timing and the 1 tooth for tdc detection, is this the correct approach here? I seen to recall Russian using the 24 and 4 on a Honda, and recently another user used the 1 but needed an additional board (which I'd rather avoid). The stock ecu pinout also puts the 16 and 1 right into the correct inputs, which is really convenient...

I believe I have the short solved (though I still need to make the actual repair) so I just need to get this figured out, test my sensors and outputs, set a basemap and get cranking! (Btw, is it a good idea to have the motor at temp with the stock ecu before I try cranking this one?)
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