Ignition input/output problems

[Metro]

It's been a while since I've posted here or worked on my car Seems like I've always had problems with spark, either getting it out of MS or getting a RPM signal in to it.

 

Anyway, I'm kind of wondering what my best options are for spark input and output with my current setup. I have a 81 L28et with the CAS. When I initially started using MSNS-extra I was using a locked 76 NA distributor (VR input) and using Moby's HEI 4 output setup. The car ran and worked pretty well aside from an intermittent miss which would screw up my in-dash tach signal (bounce around constantly). So in an effort to fix the miss I tried various things. First was to use the VB921 to handle spark output.

 

Initially this worked too, but I had to use a really low trigger angle (around 20 degrees, I think) so my spark advance/control was basically nonexistent. My only other option at the time was to try and use the 81's CAS. I eventually got it running with the CAS using the same wiring setup as the optical distributor. My new problem was around 3700-4000rpm MS would lose the tach signal completely and the motor would cut out pretty bad. Fast forward to the present and I can't even set the trigger angle, spark is very inconsistent.

 

In frustration I tried to go back to my original setup with the HEI module, but it's been a few years and I'm a little rusty at MSNS so I had problems doing that. Not to mention the whole reason I was doing this was to get a working tach signal for the dash gauge.

 

To sum it up:

76 NA Dizzy with HEI - car was drivable, but slight and constant miss.

76 NA Dizzy with VB921 - low trigger angle, stuck at around 15 degrees max advance.

81 CAS with VB921 - motor ran, but MSNS lost rpm signal around 4000rpm

 

So now I'm looking at something like using a Ford EDIS setup, but I really just want to get the car running with the simplest setup I can. Looking at other threads people just flat out say don't try and use the 81 CAS and for the price of an 82 optical distributor go EDIS. I'm going to do more research to find out how difficult EDIS is to setup (like installing the toothed wheel). I know I'm kind of rambling, it's what I do, but any input on my situation would be great.

[LanceVance]

Metro,

 

Saw on your signature that you are using a flywheel pickup, which is something I'm looking into doing myself. I found this thread while trying to find details on your build, and it seemed a reasonable and relevant place to ask about it.

 

Did you ever get it running smoothly? What are the details on your flywheel setup?

[Metro]

Oh man I forgot all about this post, I never did get the CAS figured out, but I did fix the problem with the 76 NA VR distributor. Apparently they work off a really low trigger angle, I think it was around 15 degrees. I had to tweak the VR mounting plate inside the distributor to get the right angle for MS to use. If I remember correctly, with a low trigger angle like that MS goes into next cylinder mode and it figures it out from there.

 

Don't ask me why I could run a trigger angle of 115 degrees with the HEI module, but the VB921/BIP373 would only work with a low angle..

 

I have a tendency to kill flies with sledgehammers, I was having a different problem and I decided to go with a flywheel trigger. I followed the excellent guide by X64v in the FAQ section. I'm using a Caterpillar VR gear tooth sensor instead of a hall sensor (used what I had on hand). I was running a single coil with a wheel decoder for a little over a year now. Just recently I've gone to a wasted spark setup using a GM DIS coils. I gutted the DIS control board and wired up 3 BIP373s inside to control spark. In the past I had problems when I tried mounting an ignitor on the MS board, so this keeps everything clean and separate.

[LanceVance]

I followed the excellent guide by X64v in the FAQ section.

I can't deny I pull most of the inspiration for this project from the same place. One key difference however is I WANT to use EDIS. I'm planning on mimicking his sensor mounting, but machining a trigger wheel similar to Euro Ford DOHC Zetec motors:

 

I'm using a Caterpillar VR gear tooth sensor instead of a hall sensor.

I'm curious if this would work as a direct replacement sensor for the Ford unit? I've found plenty of threaded VR sensors, but most seem to be intended for industrial applications. I haven't been able to find any detailed specifications for the Ford unit either, so ordering one of these may be hit or miss... Edited March 11, 2013 by LanceVance

[Metro]

Why do you want to use EDIS, unless you're not using Megasquirt?

 

But as for you're question, believe me when I say I'm not an expert at this, but I think it might work. EDIS is just looking for a 36-1 signal, I don't think it would matter too much where it came from. I'm not sure what the technical term is, but VR sensors just send an AC frequency, the controller just needs to sense the pulses. The one thing you would need to check is the trigger angle that the EDIS control unit expects. If you go this route, you would definitely need to build in some sort of adjustment to slide the pickup to set the trigger angle.

 

I'm not sure of the exact part number of the sensor I'm using, it's stainless steel and I think it's a 5/8th thread by about 4" long. I did manage to find a marine parts website that sold it a while back and it was about $100, but I can't seem to find it again. If I were you I'd just buy a threaded VR sensor from DigiKey and try that.

[LanceVance]

I'm planning on using Megasquirt, but I'm trying to limit the systems that are dependent on it. I've already got the cooling system with a 2 stage fan speed relay and sensor that are completely isolated from MS. I know I'll still have to connect the EDIS module to MS, but the limp mode is something I'd very much like to retain.

 

Call me paranoid, but I like redundancy and fallback systems; having MS control every aspect of the motor just doesn't sit well with me. Right now, if MS craps out on me (I doubt it will, but who knows) the car will idle, and keep itself cool.

 

The trigger angle is something I'm just going to have to carefully measure out. I'll probably place the sensor first, determine the angle and machine the flywheel appropriately. The old adage 'measure twice, cut once' seems exceeding appropriate in this case!

 

 

[Metro]

Seems like to me, using EDIS these days is increasing your complexity, not decreasing it. With EDIS you're relying on it to decode the wheel signal and then output that signal to MS (which uses the same circuitry as if it were decoding the wheel itself). If the VR input circuitry goes wonky, MS won't have an RPM signal and it won't run regardless of the limp mode built into the EDIS unit (no fueling).

 

Back in the day when MS couldn't decode wheels (or not as well) using the EDIS for wasted spark was a great option. I kind of see it as a relic these days especially with introduction of MS2 and MS3. Just my two cents, I never spent much time researching EDIS, it might have other inherent advantages I'm not aware of.

 

But that's an interesting setup you'll have, I hope the flywheel method works for you.