Microsquirt and the LH2.4 VR sensor reading a 60-2

Yeah a Hall sensor with the adapter is kind of my fallback plan at this point.

My stock sensor worked perfect with my ms2, NEVER had an issue. Part of the reason I'm stubborn to get it to work on the ostensibly "better" microsquirt circuit.

Haven't had any issues with the stock one once I put the resistor in, plus I need to be able to fall back to lh for smog, at least until I can get a cel setup working in MS. Hmm....wonder if Kenny can do that when I send it back to him....

Seems like ill be going through the same process making the VR sensor work expect im dealing with lh2.2 and moving over to microsquirt V3 w/wasted spark.Shall be a interesting journey,b280 prv 780 w/gt45 turbo.Looking at getting my sensors ordered this week then hopefully have it up and running.

Wondering if id have better luck making a stock lh2.4 VR sensor work vs the lh2.2 one?

gsellstr said:

, at least until I can get a cel setup working in MS. Hmm....wonder if Kenny can do that when I send it back to him....

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Correct me if I'm wrong, but it only needs to show a CEL when the ignition is on and the engine is not running.

You could just wire the CEL into a low pressure oil switch. The stock 240 oil pressure sender has this option.

LH2.2 is dead simple. It uses a hall sensor in the distributor for the primary input. The high tooth count VR sensor is a totally different animal.

BIGsBY said:

Seems like ill be going through the same process making the VR sensor work expect im dealing with lh2.2 and moving over to microsquirt V3 w/wasted spark.Shall be a interesting journey,b280 prv 780 w/gt45 turbo.Looking at getting my sensors ordered this week then hopefully have it up and running.

Wondering if id have better luck making a stock lh2.4 VR sensor work vs the lh2.2 one?

Click to expand...

I'm ditching the distributor and going with a accel v6 coil pack along with the 960 igniter and tps.Already have the tps adapted to the old style throttle body.Got most of my wires and connectors sorted.Just need to wait for the rest of the parts to show up.

Also from when i put a new cap and rotor on the car the dizzy was gutless nothing inside of it unlike a b230 lh2.2 dizzy.I forget what exactly type of ****ery the b280 uses for its ignition timing/sensors to be exact but it sure ain't the dizzy.

Does anyone here have an oscilloscope and is running Microsquirt V3 with the stock sensor? I'm curious what the VR+/- signals look like at cranking/idle/high rpm, and what resistors or jumpers, if any, you've added. After looking at the datasheet for the VR chip in Microsquirt V3 (MAX9926), it looks like it expects +/- 2.5volts max input swing. I want to see what some typical waveforms actually look like for the stock Volvo VR sensor. I think soldering across the internal Microsquirt jumper will reduce the signal levels by 5x.

Bobxyz, I don't have a scope. But I'm pretty close to you if you want to plug into my car.

Sure, if I remember this thread correctly, you've found the magic formula for your setup and your engine is now running fine (but StiggyPop is still having problems). Since this weekend sux, rain-to-snow (really?), maybe wait for a warm&sunny weekend. If we do it here, I can bring out my nice scope as long as it doesn't get anywhere near the spark wires.
-Bob

The way I understand it the higher the tooth count/rpm, the higher the voltage produced by the sensor.
I have read reportedly as much as 100volts! The high voltage overwhelms the conditioner.
This level needs to be reduced without going below the noise threshold and without attenuating it so much starting is a problem.
The inline resistor lowers output.
The shunt resistor (besides lowering output) knocks down noise, since noise will have a much lower potential than the actual signal voltage.
Finding a balance between the two resistances I believe will produce success.

That said, all of this grief has been put in motion by the perceived need to be able to go back to LH. (keeping the 60-1 wheel)
In Oregon for sure and possibly other states this may not be necessary.
I have passed a turbo 760 through Oregon smog, a pre OBD2 model with the Squirt laying on the floor in plain sight and a laptop open with TS running during the inspection.
1996 is when the OBD2 spec began enforcement.
Pre OBD2 cars just need to have a cat installed (checked with a mirror), Fuel filler must not be punched out, and idle emissions must pass spec.

You have options, you can modify your wheel (removing teeth) or you can install a 36-1 on the front of the motor and leave the LH wheel intact.
Or you can muddle through the resistor thing in hopes of finding success.

I am not certain there is a set value that will work in all instances. If so it would likely have been engineered into the uS.

Perhaps (2) 10k pots in a shielded enclosure and a scope or butt dyno may be the quickest route to success?

I also think that for a couple of bucks saved the MicroSquirt is not the best choice, as a MS2 on a v3.0 board can be custom built to the spec needed for most any 4 cyl install.

Mine's actually been fine, haven't done anything but it's started several dozen times and done 250 miles without any problems and I always have a laptop running to check, have done 6,900rpm. Just gonna keep driving it.

I have a followup question for qwkswede and StiggyPop, as a conclusion to this thread since you're both running ok now, can you post your final working setup details here for future reference?

- Specific engine and VR sensor
- Microsquirt V3 wiring connections for VR+/VR- signals, shielded cable?
- Internal modifications to Microsquirt - VR shunt resistor pads soldered across? extra resistors added? (where&value)
- External harness modifications - any extra resistor(s) added?
- TunerStudio configuration - wheel type, ignition input capture edge, Tooth#1 angle (for reference only, will vary by install)
- Engine starts OK? and Revs to ??? rpm OK?
- No other lingering issues/concerns?

Thanks,
Bob

I'll have to dig into the details in Tunerstudio, I'll get back to you.

Here are my hardware details:
-1992 B230F with probably the original VR sensor reading the automatic flex plate tone ring.
-Added 2200 ohm shunt between pins 32 and 33 on the back of the board, and de-soldered the built in 25000 ohm shunt.

Microsquirt VR1(+) ===> EZK pin 23
Microsquirt VR1(-) ===> EZK pin 10
Microsquirt VR(shield) ===> EZK pin 11

Engine starts great in all conditions. Tested betwee about 20 and 80 degrees F so far.
I rev to about 5700 regularly with no hiccups.

Bob, you are great - very thorough! It is good to get this info down for posterity.

- Engine: 1991 b230ft, stock CPS (bougi), picking up a 60-2 notched flat flywheel. 4 d514 coils in wasted spark.
- Wiring: DIY autotune harness with new terminals crimped for stock CPS connector. Twisted shielded pair, wired as follows:
o VR+ > connector pin 1
o VR- > connector pin 2
o Shield > connector pin 3
~ Other end of the shield wire is connected to Sensor Ground on the uS end
- Unmodified, unopened Microsquirt v3
- No resistors in harness
- TS: missing tooth wheel, going high, rising edge, TDC angle I believe was around 85 but I need to go check.
- I see a clean uninterrupted crank signal after 1 or 2 revolutions cranking and have not been experiencing starting issues any longer.
- Revving up to 6,850rpm redline with no issues.

There was a fair bit of trial and error involved in this for me, and I definitely put more thought and time into this aspect of the project than I expected. That said, since I wired the sensor according to the above, I have not had any issues with sync loss driving at any revs, and I really spin the car. I did, initially, have only a couple instances where I had some sync loss during cranking. Mostly it was one time after filling up where I cranked for ~10seconds and it just didn't sync up. I cycled power and it started, and I think that's the last time I had problems starting the car. I haven't changed anything since and I've started the car dozens of times without any issues.

At this point I'm hoping I'm done thinking about it! I still check the logs and figure if I have any more issues during cranking I'll address it as it comes. Few hundred miles of happy operation now, so I'm cautiously optimistic that it's set.

Was having a similar issue not able to rev past 3000 rpms. Installed 4700 ohm resistor across the vr+ and vr- on the back of the board and voila. My setup is: volvo 60-2 flexplate, factory cps volvo sensor wired directly to the micro squirt.

It was mentioned earlier in this thread about tapping into the EZK vr conditioner circuit. Would you just tie the OPTOIN+ to the conditioner out?

qwkswede said:

Bobxyz, I don't have a scope. But I'm pretty close to you if you want to plug into my car.

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I want to buy a scope myself here soon. We have one at the shop built into the $14k Snap On scan tool, but I feel like I am walking around with my boss' baby when I am holding the thing.

I want to buy my own scope and learn how to use it well. I found the entry level PicoScope stuff is only $129.

https://www.picotech.com/products/oscilloscope

zinkie said:

It was mentioned earlier in this thread about tapping into the EZK vr conditioner circuit. Would you just tie the OPTOIN+ to the conditioner out?

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you tie the conditioner output pretty much directly to the processor (forget which port it is off hand, but it was fairly obvious), but that for whatever reason didn't work as well for Redleg and his microsquirt.. since you can't really bypass the conditioner circuit (although, I'm still curious about that). But if you've got an old v2.2 ms board, or even the v3 board, stealing the signal off the ezk is a fantastic option

Why are you going into the case? I posted about this almost a year ago, on the fix, without going into the case.

that's the case on the ezk box, not the microsquirt box.