MPGuino in CRX
 

Alright, so I couldn't find the information any where else.. I have a 1989 CRX HF and I can't figure out what injector to tap into and where the vss line is located.... Any help would be much appreciated.
Thanks

This might be helpful : crxMPG – Gas mileage never looked so good » SuperMID: Fuel Economy Display

No I've read that before. It doesn't tell me what wires to get in to.

this might help. OBD0 pinout diagram on honda-tech.
looks like B16

Obd0 Pin out - Honda-Tech

My B pinpoints are different than that... I have that photo..

does your ecu have 2 or 3 plugs? honda OBD0 pins should be standard across the board. is it possible the previous owner did a swap on the harness and ecu?

pics will help

3 plugs. Previous owner didn't have an ECU and he said that he didn't swap anything..
I'll post photos tonight..

if it's 3 plugs, it's a OBD1 ECU/harness. check the OBD1 diagram here

ECU Pinouts, VTEC wiring, & ECU VTEC Conversion Information - HondaCivicForum.com

if your B10 is yellow/blue or orange color wire, then that's the one for your VSS

while you're at it, you can also check the ECU number and see which one your CRX is running to verify that it's a OBD1
Honda ECU List - HondaSwap Forums

if you're engine isn't original, check the engine model stamped on the block. here's a list of honda motors to triple check your OBD1
Honda Engine List - HondaSwap Forums

Mine looks like that obd0 one. Not the obd1

Here's my ECU and wires..
Quick photos.. sorry for the lack of detail.

https://lh3.googleusercontent.com/-7...A53%2520PM.jpg

https://lh3.googleusercontent.com/-z...A27%2520PM.jpg

The MPGuino needs an injector "signal" from the injector's ground wire.
Reason is, the positive wire is always hot and the ground is switched by the computer to control injector pulses.

On my '97 Civic I hooked mine up at one of the injectors. Doesn't matter which one. Check for voltage in the two injector wires with ign switch in "run" position, and use the wire that has no voltage. That's the switched ground. Yes you also could find that wire at the computer harness but I was more comfortable tapping into it at the injector.

Good luck with it - super project! Project thread, in case you haven't stumbled on it:
http://ecomodder.com/forum/showthrea...crx-17565.html

I hooked it up to the ground wire on this injector
(last on the left)
https://lh4.googleusercontent.com/-m...A56%2520PM.jpg

Onto this ground wire from that injector
https://lh3.googleusercontent.com/-G...A49%2520PM.jpg

And when I start it up that injector misses completely..

This whole MPGuino is starting to piss me off a bit.. I've spent hours on the case for it and it looks terrible and I can't even figure out how to wire it up right.
But hey, at least it powers on right.

Thanks for the help so far btw. I appreciate it.

Did you try with other injector wire? How you connected pins to socket?
Did you find VSS signal?

Dont give up, this little thing is worth these few hours ;)

edit: I googled "honda crx hf ecu pinout" and find this:
http://cx4fwq.bay.livefilestore.com/...u3/pinout2.jpg

So probably you need one injector (example "INJ 1") and "speed pulser" wires (VSS)

So do I need to connect to the actual injector or or the ground for the injector?? I soldered the pins to my wire... Crappy job though. Best I could do. My VSS is mechanical.. Will it still work?

If i remember correctly, the Hondas keep the injectors high at 12v most of the time, then drop to GND to fire them. So, no, you don't want to mess with the GND wire of the injector. You want to tap into, as meelis suggested, INJ 1 (pin A1 on the ecu). The mpguino will then see the 12v get pulled down to 0v during the injection.

When you say your VSS is mechanical, do you mean you have a mechanical speedo cable spinning inside your gauge cluster? Even if you do, there may still be a high-low electrical signal coming out of the cluster, for use by the cruise control. Hopefully your B18/B19 "speed pulser" is the speed of the wheels, not "engine speed" (aka Tach).

Okay. I tapped into the injector one. Now my car is idling strange and the check engine light is on.

Yeah it goes from the cluster to the tranny and is mechanical, spinning..

This is rediculous. I capped off my spliced end and it's still running like crap, dying and the check engine light is on! This MPGuino is screwing up my car

Can you read this code somehow? Maybe you touched or disconnected some other things when you did this mpguino installation? You could try to remove one wire from battery for a few minutes - so car ECU resets and clears errors.
I have hard to believe that mpguino can disturb car and ECU if installed properly.

I did remove the negative terminal for a few minutes and it didn't clear. I'm sure it's the way I've installed it but I just can't be trying to wire it up every night only to have my injectors miss and not be able to drive it the next day.

I hooked into a constant power, with a 10 amp fuse, I used a ground, I took the pin out of injector 1 spot and soldered the injector feed on to that and put it back in the pin slot perfectly. I capped off the VSS line and left that alone since I don't know where to connect that, started the car up and the injector was missing completely. It would randomly die too. Now it still misses and I can't get rid of the injector codes and I think an electrical load code. Check engine light is still on.

I'm not saying its the MPGuinos fault, but I didn't think it would be this difficult to get it working.

This link should give all the details you need for hooking up the MPGuino. CRX Community Forum • View topic - MPGuino

My best advise on wiring mods is to never touch the stock wiring under the hood unless there is no alternative. Your splice at the injector is a major long term reliability problem that will eventually fail. It's much better and easier to make the splices at the ECU.

I read your build thread and have a couple comments.

If your fuel line splice is on the low pressure return line it would probably only become a problem during an accident. If the splice is on the high pressure supply line it's incredibly dangerous and should be fixed properly before further driving.

For your interior restoration keep in mind the HF did not come with a cargo divider to save weight. The back end is mostly open on the stock HF.

You mentioned buying an OEM muffler for $75. Is that a genuine Honda OEM muffler for an HF or is that something else like an OE replacement muffler or DX muffler?

Mike

Ill risk it on the spliced fuel line. Im young.

Yeah I am keeping interior stock without the dividers and such.

I have no idea on the muffler... Guess ill find out when i start driving it.



I think that when I went to hook up my MPGuino, the connector was not making full contact.. Stupid fault of my own. Once i get done with the body work I'll probably throw it in and I'll do a how to for all the CRX owners on here..
Thanks for all your help and I apologize for the complaining haha.

Hey,
I am bringing this back from the dead. Also apologizing for acting like such a baby when it didn't work..... Haha.

I am attempting to put this back in now and I just don't know where to hook up the VSS.

Any hints, ideas, possibilities?

Thanks everyone.

Thanks to Cherish (myrefugeisinthelord) I got a page from her nifty book.

So I am thinking that the Speed Pulser is the same as the VSS. Is that a fair assumption? Here it is in the diagram..

https://lh6.googleusercontent.com/-v...le%2520VSS.jpg

That is the red and yellow wire going into B18 or B19 on your ECU.

Hey Wyatt, here's something else I found in the electrical manual.
The connection #C406:
http://i1063.photobucket.com/albums/...ps8c68e47c.jpg

Is located behind the fuse box, here:
http://i1063.photobucket.com/albums/...ps7c3a21fa.jpg

Sorry about the poor quality photo. It's not very good in the book, so it didn't come out very well.
That bit of info might give you a few more options on location stuff. :)

So ummm I need some help from all you MPGuino experts :D

My MPGuino is being very sporadic. Instant Mileage jumps from 50 to 150 to 89276.... Then current mileage just keeps climbing and climbing.. It wasn't doing this until I tried coasting with the key off then bump starting.. I have tried resetting everything and disconnecting from power..

Nothing.

Any help??

Any updates?
Instant mileage is calculated by two values - speed and consumption. If one is bad, then instant mileage is rubbish.

I suggest you check instant speed reading and fuel consumption per hour reading.
They are "almost" raw readings from injector and speed sensors (of course multiplied by pulses/mile and microsec/gallon readings)

* liters/hour or gallons/hour reading in idle should be realistic (what is realistic, depends on your car: 0.5L/h ... 1.5L/h) and not jump around much.
* instant speed should not jump around much, if it does, then there is a problem
* if instant speed is correct and injector signal is missing/bad connection, then mileage jumps to high levels - mpguino thinks you are moving but fuel is not consumed.

Meelis

Instant speed is correct until I get to 70mph. Then it starts to get sporadic and fall back down to 68-69 then jump up to current speed for a second then does it again...

I'll check fuel consumption per hour once I get in my car this morning..

It was normal yesterday, which is wierd.
When it was acting off I was at about 95mpg Cm
Now it's at about 64mpg Cm and the instant is reading correctly..

About how much does instant supposed to jump around? A couple mpg? Ten mpg?

I'm looking at a steady 0.87 Gallons per hour... Slowly climbing as I sit here and idle..

Also, my Cm drops fast when I just idle. Is that normal? I'd assume so..

I had the same issue happen once. The speed signal would jump around like crazy. I think the guino got confused with a key off somehow.

Yeah I can't key off or it happens... So I guess I'll have to make a kill switch.

So do you think that is my problem Meelis? Just keying off messed it up for a bit?
If that's the case thn it doesn't make sense to me how it didn't get fixed after skis connecting it from the power and resetting everything...

If you key off the reed switch in our older cars no longer produces a signal. The ECU shuts down... maybe the combination of the 2 things cause the MPGuino to go nuts. I found if I shut down the engine with the key and wait 1 or 2 seconds before keying on again the MPGuino behaves.

When mine messed up it was some time before the MPGuino started working correctly again.... but it did start to work on it's own again.