Honda CRX - MS II fuel and spark, stock everything

[Abaddon]

I'm trying to get my '90 Honda CRX up and running with MSII controlling fuel and spark all with the stock EFI hardware.

Engine is a 1.6L 4 cylinder with 4 injectors (low imp with resistors) and its OBD0. I've got everything wired up. I get good readings on TPS, intake air temp, coolant temp, and MAP. For a trigger, I'm using a 4 tooth (spaced 90 degrees) VR sensor in the distributor driven off the cam (1 rev per 2 revs crank). I seem to get 200-300rpm readings while cranking so I beleive its a good trigger.

For spark coil control, I've got pin 37 of the MSII connected to a pin on the stock Honda Ignition Control Module (ignitor), but I've read conflicting info on how the ECU triggers the module. I've read some reports that the signal is grounded to trigger and some reports that the signal is taken high. I've attached a diagram of how the ICM and coil are wired.

Here's my problem,
Step 1. Car runs fine on stock ECU.
Step 2. Connect MSII and crank it over, I get some sputters and a spark or two and then nothing.
Step 3. Connect the stock ECU back up and crank, nothing.
Step 4. Replace the ignitor and she starts on the stock ECU.

Some how MSII is killing my ignitor unit. I'm not sure what the issue is.

Basically, can MSII work with this ignitor unit? Does anyone know what is the triggering mechanism for this unit (ground/high)? Do I need to worry about the dwell settings in MegaTune when using the ignitor unit or does the ignitor take care of that?

The ignitor unit has the following markings: NEC MC-8132

I feel I'm so close, I've converted over the stock ignition map, generated a fuel map, wired up to the stock harness. If only I could stop killing ignitors. Please help if you can and thanks in advance.

PS, I'm not sure of the trigger offset for the VR sensor (if there is one). I hoped to get the engine somewhat running and determine this with a timing light, but if you happen to know, that info would be great as well.

[nfn15037]

Too much dwell will kill Honda ignitiors almost instantly. I went through this with an AEM EMS on a customer car. At any rate, if it was my car, I'd use the MS to trigger the coil directly and leave the ignitor out of the equation.

[Abaddon]

Thanks for the tip, my goal is to use all the OEM hardware, so I'd hate to give up on the Honda ignitor just yet.

I have the dwell setting in MegaTune set to 3ms. I suppose I should stock up on ignitors and start with something like 1ms then?? Is there any way I can determine the dwell setting that the stock ECU uses? Did you come up with a solution with the AEM EMS that used the stock ignitor? Finally, do you happen to know what triggers the ignitor unit (signal going low or high)?

Thanks, in advance.

[Abaddon]

I was able to find this site with information on the Honda ignitor:

http://www.tegger.com/hondafaq/igniter- ... index.html

In the case of ignition, they claim the stock ECU is only a timing trigger. They seem to believe the Honda ignitor unit is capable of managing coil dwell itself to maintain the proper coil saturation.

1. If this is the case, what effect do the dwell settings in MegaTune have on this unit?

2. Why would the MegaSquirt be killing the ignitor unit?

They also claim the ECU triggers the ignitor by taking the input signal from 10V to 0V.

3. Could the MegaSquirt be providing a signal with too much voltage (12-13V)?

Perhaps I should add a resistor to the signal to create a 2V-3V voltage drop??

I feel like I'm so close... yet so far.

[jassem99]

According to this site the dwell on a Prelude is 3.1ms, and the ignitor triggers on a rising edge. Not sure if the CRX is similar.

One thing to do is to check the voltage that the ignitor sees from the ECU with the ignition switch on and the engine off. Then set up the MS to replicate that condition. What you don't want is for the MS to be triggering the ignitor with the ignition switch on (feel the ignitor for excess heat).

On a side note, from what I've read, the 4 tooth TDC sensor on a honda can't be used to trigger a standalone. I wonder how you are getting a signal and at what trigger angle?

Finally, I think you should get the car running by driving the coil directly and then worry about getting the Honda ignitor working. Good luck.

Basil

[bobnova]

I've used all OEM hardware on my 89 prelude, but i'm using a V2.2 board and v1 chip.
My dwell settings are whatever came in the config file, i think. I don't have access to 'em at the moment.


You might try triggering the stock ignitor without the VBwhatever it is chunk of the V3 board hooked up.
Alternatively, you could build a jumper that goes in place of the stock ignitor, so that your signal from pin 37 goes directly to the coil instead of through the ignitor.


The TDC sensor will work just fine for triggering megasquirt.
Other standalones may want more teeth, but MS is happy with just four.

[Abaddon]

Thanks for the advice.

I'll try and take another look at everything this weekend. Hopefully I can get access to an oscilliscope and get an look at the stock ECU's signal to the ignitor.

[Abaddon]

Alright, so I was able scope the stock ECU signal to the igntor. I've attached some scope shots to this post (1000 rpm and 4000 rpm)

The signal is high (+12V) with the ignition on, engine off.

At 1000 rpm the signal goes low (0V, ground) for ~3 ms to signal the ignitor. The time the signal goes low decreases as rmp's increase. Does this mean the ECU is controlling the dwell time as well? At 4000 rpm's the time the signal goes low is ~2 ms.

I hooked up the MegaSquirt and turned on the igntion, engine off. I got a reading of 5V for the signal. I read in the V3 assembly manual "You do not need a pull up, the processor port has one enabled already (at 5 Volts)."

Can I change the value of this pull up resistor to get 12V and use the processor port to control the ignitor OR do I have to use the high current ignition driver to control this ignitor since it requires a 12V signal??

[Abaddon]

Success!!

Thank you to all.

I went ahead and wired up the high current ignition driver to control the Honda ignitor. Works like a charm (once I remebered that it inverts the signal of the Spark Output). I figure it's better than changing the value of the pull up resistor for the processor output to make it +12V.

She now runs like a champ. Having the stock ECU timing map helps A LOT. Just 30 minutes of tuning the fuel and she's running almost as well as on the stock ECU.

Again, thank you all. My turbo project can now get underway ;)

[jacobrussell]

Success!!

Thank you to all.

I went ahead and wired up the high current ignition driver to control the Honda ignitor. Works like a charm (once I remebered that it inverts the signal of the Spark Output). I figure it's better than changing the value of the pull up resistor for the processor output to make it +12V.

She now runs like a champ. Having the stock ECU timing map helps A LOT. Just 30 minutes of tuning the fuel and she's running almost as well as on the stock ECU.

Again, thank you all. My turbo project can now get underway ;)

um can we get the timing settings from you man we also need trigger angle settingsa you used

[abettertomorrow80]

Hi Abaddon. i need the tune map fueld and ignition from your tuned honda CRX. could u hook me up please? lol

i have a 1993 prelude H22 VTEC motor OBD1 stockECU and distributor. I m looking to buy either MS2 v3 or MS2 v.357

i m still thinking how to add vtec circuit to ms2 v3 or v3.57. i want ms2 to run parallel to stock HOnda ECu where ms2 control fuel and ignition and vtec control.

megasquirt said there a vtec circuit to add to either ms2 or ms1 is fine.