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Cherry hall sensor RPM spikes

ZVOLV said:
Why not just use a hall sensor built into a distributor? Like from a 75 240. Just an easy guaranteed squarewave and you won't have to mess around with airgaps.
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That would work if he was prepared to convert back to the equivalent of triggering off of the ignition points. The 4 gap sensor 'wheel' in that type of arrangement would be equivalent to a 2 tooth crankshaft wheel which means he would be losing an awful lot of resolution on his tach speed signal. Not so good if you are attempting to implement ignition control in the Megasquirt.

If he wants to go that path, he doesn't need to find a 1975 distributor. All he would need to do is install a Pertronix module on his existing distributor with pull up resistor and lock the advance mechanism. It does require advancing the distributor timing significantly compared to stock which can create some problems with the phasing of the rotor in the distributor.

Since there is no cam / cylinder position signal with this arrangement, it would preclude any type of COP or wasted spark arrangement.
 
Using MS1, he doesn't have any resolution anyways. Even with a 36-1 wheel, the back end of the code still treats triggering as a basic 2 tooth crankshaft wheel. MS1 doesn't calculate control events per-tooth like MS2 and MS3 does. The only thing you gain with a cam tooth or missing tooth wheel in MS1 is the ability to run distributorless ignition. Resolution is still only as finite as you define in trigger event settings.

Biggest selling point to upgrade to MS2.
 
Yeah, I'm looking at the upgrade to MS2 just wanting to get my legs under me with the whole standalone stuff. So far I'm learning a lot, but there's still a lot to learn.

Next step is LS2 coils, then the swapover to MS2.

Thanks for the help!
 
gross polluter said:
Using MS1, he doesn't have any resolution anyways. Even with a 36-1 wheel, the back end of the code still treats triggering as a basic 2 tooth crankshaft wheel. MS1 doesn't calculate control events per-tooth like MS2 and MS3 does. The only thing you gain with a cam tooth or missing tooth wheel in MS1 is the ability to run distributorless ignition. Resolution is still only as finite as you define in trigger event settings.

Biggest selling point to upgrade to MS2.
Click to expand...

I have never dealt with MS 1 - that's a downer. If that is the case, since the OP is currently running a coil and distributor for spark, ZVOLV's comment about using an early Volvo pointless distributor (or Pertronix on his existing distributor) is reasonable. I know that people have made it work on B20s so the phase shift on the rotor must be manageable.
 
When I was running just fuel I was able to use the stock tach output from the MSD 6A for triggering the MS box. Went to the DSM CAS and dual BIP's later on (Thanks Nick), still on the MS1V3 setup.

The 75 dizzy is a VR input anyway, but I can't imagine it's all that fine in terms of resolution.
 
cwdodson88 said:
Yeah, I'm looking at the upgrade to MS2 just wanting to get my legs under me with the whole standalone stuff. So far I'm learning a lot, but there's still a lot to learn.

Next step is LS2 coils, then the swapover to MS2.

Thanks for the help!
Click to expand...

If you are going to switch to MS2 and ditch the distributor, consider the move to the Yoshifab adapter with the optical CAS and the Yoshifab higher resolution trigger disk. A much tidier arrangement and uses OEM grade devices. The tach resolution is not as good as a 36-1 wheel; but, it is nice to not have that hall device tacked on to the front of the engine waiting to get bumped by something.

Rock Auto sells OEM (Auto7) CAS units for the 1994 Hyundai Sonata for around $50. Comes sealed in a Hyundai bag in a Hyundai box with Hyundai part numbers - first time that I have ever had an OEM part at a lower price than aftermarket!
 
I was suggesting that the OP maybe just find a way to get a stock Volvo dist in there that contains a hall sensor.

I would first create a running engine and THEN worry about getting something with "more resolution" in there. Just the standard vanes passing thru a window will work just fine. Especially for a mild B20 build. Sounds like the software isn't even strong enough to deal with high resolution triggers, so sounds like a waste of time anyways.

Fun experiment though. It would even be better if you were monitoring your changes with a scope so you could actually see what is going on.
 
Engine runs, I drive it to work every day. The plan has always been to upgrade if I get to a point of comfort with the less complicated install, the intention was to see if I even like mega squirt, turns out I do. So an upgrade is already in the workings, soon it will be running ms2, and dual triggers with sequential coil near plug.
 
Sounds like a fun project. I'm getting bored driving a 1990 245 M47 NA. I miss my 1975 244, 1975 245 and my 1974 145. They were just so much money to keep on the road for a car that werent safe to drive triple digits! They were barely safe to go on the freeway in their condition. Well, the 1975 244 had a B230FT and I ran it on E85 and the weakpoint was the nonvented front brakes. They would get smoked just boosting hard down a city street and coming to a stop.
 
I am installing my megasquirt in stages. Started with Ignition only to make sure all other inputs are working well. Just using points for the RPM input for now. The points input is super noisy. Couldn't even start it until I used some heavy handed filter settings. There is a narrow window between filtering noise and over filtering and getting incorrect RPM feedback. I know this setup is not ideal and not what I am planning on using long term, just playing around with MS with the car in a state where I can drive around and easily switch back.

My point here is that I don't think MS is as robust as it could be from a noise perspective. Been running a CB programmable ignition for over a year and it never had a single hiccup running off the points. It has what I would consider a worst case installation from a noise perspective. The cpu is mounted right next to the coil, powered off of coil positive and just grounded to a hinge screw and it requires the distributor to be phased 75 BTDC so there is a big high voltage spark in the dizzy.
 
carbonmike said:
Just using points for the RPM input for now. The points input is super noisy. Couldn't even start it until I used some heavy handed filter settings.
Click to expand...

Hmmm, what MS input circuit are you using (Opto or VR)? And you do have an appropriate pullup resistor? How about your ground/pickup wiring to the distributor?
 
carbonmike said:
I am installing my megasquirt in stages. Started with Ignition only to make sure all other inputs are working well. Just using points for the RPM input for now. The points input is super noisy. Couldn't even start it until I used some heavy handed filter settings. There is a narrow window between filtering noise and over filtering and getting incorrect RPM feedback. I know this setup is not ideal and not what I am planning on using long term, just playing around with MS with the car in a state where I can drive around and easily switch back.

My point here is that I don't think MS is as robust as it could be from a noise perspective. Been running a CB programmable ignition for over a year and it never had a single hiccup running off the points. It has what I would consider a worst case installation from a noise perspective. The cpu is mounted right next to the coil, powered off of coil positive and just grounded to a hinge screw and it requires the distributor to be phased 75 BTDC so there is a big high voltage spark in the dizzy.
Click to expand...

You talk about 'filter settings'. If you are talking about the Averaging Lag Factors in the sensor settings in Tuner Studio, you should not be treating those as noise filters. They are averaging functions applied to the signal at the digital level and are there primarily to slow down the response of the MS controller. If you have noise which is causing the MS analog inputs to erroneously generate superfluous tach signals for the processor, you need to deal with that by filtering the analog front end (C12 & C30) or address the cause of the noise issue because other people have made ignition control off of points work with MS. If you are making the MS work by adjusting the lag factors, you are not addressing noise. I expect that the RPM lag factors don't even enter into the portion of the code associated with ignition timing control - it may be a fuel only thing.
 
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142 guy said:
You talk about 'filter settings'. If you are talking about the Averaging Lag Factors in the sensor settings in Tuner Studio, you should not be treating those as noise filters. They are averaging functions applied to the signal at the digital level and are there primarily to slow down the response of the MS controller. If you have noise which is causing the MS analog inputs to erroneously generate superfluous tach signals for the processor, you need to deal with that by filtering the analog front end (C12 & C30) or address the cause of the noise issue because other people have made ignition control off of points work with MS. If you are making the MS work by adjusting the lag factors, you are not addressing noise. I expect that the RPM lag factors don't even enter into the portion of the code associated with ignition timing control - it may be a fuel only thing.
Click to expand...

Haven't touched the lag factor yet. I am talking about the Noise Filter options under the ignition settings.
 
Are you using something other than MSExtra? The only filtering I see under Ignition Settings is for the EDIS module and that would not seem to be consistent with using points. Are you talking about that masking function in the non MSExtra code?
 
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