Another HEI - no RPM question

[Bigdav160]

New guy here but not to fuel injection or conversions. I did a forum search and didn't see anything I haven't checked

New V3 Microsquirt I bought two years ago installed on a 350ci with PFI (stealth ram) fitted into my '72 Chevrolet Suburban 4x4. I'm using a small cap (8pin) HEI

I finally finished up all the supporting systems and today was my first attempt at start up. After I configured all the particulars per the manual I have a crank - no start condition. No RPM's detected in Tunerstudio.

Needlessly I think, I dissembled my harness, reading that Optoin- needed to be grounded. It's not, just floating. All the other connection proved correct also. I do have great strong spark at the ignition coil. A few hydrocarbons in the intake and it'll fire off.

I don't have an oscilloscope so instead I used my powerprobe and verified good blinking (@ 2 volts (average?)) while backprobing the Microsquirt's Optoin+. No blinking on the tach output, Ign1 output or the injector drivers (pin 9 and 10).

Now I'm guessing my problem is in software. I changed the trigger wheel settings to zero and disabled the dual spark but have no change.

I'm not sure where to look next. Can anyone help?
The firmware code is listed as 3.83 and Tunerstudio as 2.6.14.

[Bernard Fife]

As well as a log (.msl), we need to see your MSQ settings file as well (it will show us how you have your MicroSquirt set up).

Lance.

[Bigdav160]

I'm glad you posted the file extension. I had to look for it.

TIA for any insight you can share with me.

1972 Suburban 1_2014-07-05_18.30.46.msq

(31.25 KiB) Downloaded 145 times

I think I'm finding some inconsistencies in the manual. From this page: http://www.useasydocs.com/details/GM_7pinHEI.htm
it says:

tach signal is a purple wire with a white trace [pin R] goes to Ampseal OPTOIN+ pin #30 (ground the Ampseal OPTOIN- pin #31 at the distributor)

.

A paragraph below that it says:

The ignition signal going to your MicroSquirt® controller comes from pin R of the 7-pin HEI module and goes to the Ampseal VR1IN+ pin 32. Leave the VR1IN- pin #33 unconnected (do not ground it).

Then in this thread
Lance says:

What you should do depends on which version of MicroSquirt you have. If you have a V3 MicroSquirt, OptoIN- should NOT be grounded. It should be left 'floating'. You do that by snipping the lead off, and taping it up so that it is not connected to anything at all.

This is how my Optoin- is connected - to nothing.

[Bigdav160]

Last night I wired Optoin- to ground as suggested in the instructions. I still get a flashing (ground) logic probe signal on Optoin+ but no RPM signal. I did notice that the voltage on my probe dropped to .9v from the 2v it was seeing with the Optoin- floating.

I then wired a LED to the accel LED wire and hooded up a spare distributor. When I spin the distributor I get a single flash of the LED

I thought maybe my signal is too weak. (I did read that Optoin+/- should be used for coil triggering) so I thought I might try that. I was hesitant to wire Optoin- to 12v after reading that some people have burned out that circuit on the board when using it that way.

How about using VR1?

I'm not sure where to look from here. I might look into trying to borrow a oscilloscope to give me more insight on why the Microsquirt is not seeing my RPM input.

[Bigdav160]

I've made my nice neat harness into a rats nest tracing circuits to make sure they are correct. If there was any positive outcome is that I improved some circuits in and out of the pre-assembled bussman relay box I bought.

Things I've tried -
Ignition reference from the HEI module to Optoin+ leaving Optoin- floating - no RPM recognized
Ignition reference from the HEI module to Optoin+ leaving Optoin- grounded to distributor - no RPM recognized
Optoin+ hooked to the negative side of the ignition coil and Optoin- hooked to 12 volts - no RPM recognized
Ignition reference from the HEI module to VR1+ and VR1- floating - no RPM recognized

Replaced the 4 pin module connector with a brand new connector (he pins would back out of the old one if I wasn't careful)

I haven't changed software from the recommended ignition settings
Ignition Input Capture-Rising Edge
Cranking trigger-Trigger Rise
Coil Charging Scheme -Standard Coil Charge
Spark Output-Going High (Inverted)

except for disabling dual spark and playing with the trigger wheel number. Still no RPM signal recongnized. All while I getting a flashing ground signal on my powerprobe while backprobing pin 30.

I did, as an experiment, try the injector test mode and got a signal at my accel LED before all hell broke loose. The Microquirt started rebooting over and over locking me out of TunerStudio. I was forced to reinstall the firmware and tried the version 2.920. I then re-did those previous steps above with no change.

I have probably 20 hours in playing with it this week. I'm pretty much out of ideas now.
I've never had an OE computer not start right up. Perhaps my expectations were too high.

Anybody have some insight before I bail? I checked and I purchased this module from EFI Source. Do they offer any support? It's a little slow here.

[Bigdav160]

Thinking that my chinese Skip White distributor module wasn't sending a clean enough signal, I turned my Arduino into a square wave generator.

5V @ 16.7 HZ hooked to Optoin+ equals no RPM signal in Tuner Studio. I think that circuit's dead. I took the covers off the unit and

those semiconductors are so small I can't hardly see them under magnification. Yikes.

[Bigdav160]

Took the cover back off the Microquirt, placed my meter leads across R20 and it shows open.

I'm not sure if that would affect the use of VR1.

The only thing I can guess is that I got someone's returned unit.

[Bigdav160]

Today I found a mistake in my wiring. I grounded the sensor ground circuit to the engine. It is also the same spot I grounded the ignition module.

Could that cause an open in R20?

I talked to Mike @ EFI Source and he said every unit, they sell, has been tested. He said "send it back" and he'd fix it.

[Bigdav160]

Just an update if anyone is following this thread. Sent my microsquirt back to EFI Source. It looks like they replaced R20 with a 500 ohm resistor. Mike said it would be of a higher wattage. It looks to have 102 or 201 printed on the top. He added a note that said "tested".

Anyway, my results are the same. Strong blinking LED (ground) with 1.6v-1.9v @ optoin+ ampseal but ZIP, ZILCH, NADA on Ignition output or Injector output. Also no RPM signal in TunerStudio. I've checked continuity between my connections and the Microsquirt. Although, i will say, I'm struggling with some inconsistencies in the manual. Such as, on the grounds/wiring page:

This is one of several ground wire pins (18 through 23). All of the ground wires should be run to the same spot on the engine (to avoid ground loops)

I'm sure this is how I connected the sensor ground to the other grounds @ the engine.

I'm weighing my options. I have an OE controller and connector in my garage but would need a prom/calpac. I could run to the salvage yard and find a compatible OE controller (I've heard the early 90's model GM trucks are well regarded in a PFI conversion). I might be able to borrow an OE distributor to try (just in case this chinese distributor signal is not what the Microsquirt wants.) I could purchase an Accel dual hall-effect distributor (very reasonably) but could I drive the ignition coil (MSD) directly? or would I need to wire up a driver? I'm still not sure. Is this a V3 vs V2.2 issue?

I've seriously have too much time in this problem to recommend the Microsquirt to others. I do understand the desire for flexibility can lead to unanticipated consequences in some applications.

[Bigdav160]

I really hate throwing in the towel. So I plug in an arduio into my laptop, load it up with a 16 hz 5 volt square wave program. With tunerstudio running and the anode pulse hooked to the distributor connector, I now have RPM and injection.

Now I'm wondering if I shouldn't reverse my Optoin+ and Optoin- connections? Or should I reverse my software settings? Another curiosity is on the MS HEI page it shows the green wire of the VR sensor hooked to the negative terminal of the HEI module. All the 8 pin distributors I seen have the white wire hooked to that terminal. Could that make a difference?