Hi,
I successfully converted my car to run on Megasquirt which is now controlling fuel and spark.
However, with the stock ECU gone, there is no field current going into the alternator, and the
battery is not getting charged. Does anybody know how to fix this problem?
Can I use an older external voltage regulator for alternators?
Cut the red wire from the alternator and tap it into one of the hots for the fuel injectors. This is what I did with mine.
Your problem is that the ECU is not turning on the alternator. Doing the above will give it 12V+ reference. Ideally you'd want something that's only hot in run (injectors are hot in run and crank). The alternator will turn itself on this way. Some say you should run a resistor in the line too, but I'm still getting 14.3V while running without having a resistor.
i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick
I say tap a wire that's hot in RUN only because that way the alternator won't turn on during cranking. This will make it easier to start. If it's on something like the fuel injector wire it'll turn on the alternator during cranking and create drag on the starter.
BEST way to do it, would be if you have an extra output on your MS. Then you could use a relay and set up the MS to set the ground on that relay any time the engine is over 400rpm. Which is why your stock ECU doesn't turn on the alternator now. It isn't getting a tach signal, so it doesn't know the engine is running. Since it doesn't see a running engine, it doesn't turn on the alternator for you.
i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick
Xardas91 wrote:Hi,
I successfully converted my car to run on Megasquirt which is now controlling fuel and spark.
However, with the stock ECU gone, there is no field current going into the alternator, and the
battery is not getting charged. Does anybody know how to fix this problem?
Can I use an older external voltage regulator for alternators?
Which MS? I'm doing MS3 in my 95 J body.
dennis
I get what you're saying, connecting the red wire on the alternator to a 12V source will turn it on. Right now I'm using two of my MS spare ports to turn on the radiator fan and to provide 5V to the DIS module when cranking. I could use another spare port to provide 12V to the alt using a relay whenever the revs go over 300 rpm.
I still had a question though: doesn't the stock ECU modulate the amount of power the alternator is making depending on TPS position, coolant temp, MAF and rpm values? If I have 12V going into the alt, does it mean that it's working at 100% all the time? From my understanding the red wire turns on the alt, and the grey one provides a signal for the field duty cycle. which is controlled in a similar fashion as the injectors, using Pulse Width Modulation (PWM).
BTW, I'm running a MS2 v3.0 controlling fuel and spark. Ignition is handled by an DIS module which was used in the late 80s early 90s.
My cooling fan and fuel pump is controlled by the MS in mine. But I'm pretty sure those are just grounds for that particular relay. So it won't give your alt a Hot to use one of those (hence why you use a relay and just turn the ground on to the relay, in the proper scenerio).
I don't think the ECU does any of that for the alternator. I think it just turns the alternator on when the engine starts that way it doesn't run on and drag on the starter when you're cranking, but i'm not sure if it does or not. In either case, the alternator has an internal regulator and will regulate itself depending on demand. Like I said, I have a constant 14.3 all the time on mine, no matter what's going on.
The red wire turns on the field. The grey wire is a voltage output for the ECU. You can have just the red hooked up without the grey wire and it'll still work fine.
i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick
I don't know about the jbody as I can't dig that far in the bin of one. How ever the v6's use different offsets for the alternator based on rpm. I assume the j-body bins would be similar as well. Also how you said to hook the alternator up is how my swap is done. Which is the 05 grand am stock wiring where it is one wire off the alternator to a switched 12 volt. Would have to go out and double check it but pretty sure that is how it is. I could also tell you what pin to use as the j-body alternators are likely to be the same.
The J-body and the V6's alt. use the same plug. I'm using my J-body plug in the V6 alternator. So you'd be good with that info.
I was thinking of setting mine up to the MS with the relay and allowing the MS to have the alternator off under 400RPM to keep drag off of the starter, and above 80% throttle to cut it out for some more power. So long as i'm not getting a hp loss affecting me from the lower voltage I'll keep it that way.
i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick
Xardas91 wrote:BTW, I'm running a MS2 v3.0 controlling fuel and spark. Ignition is handled by an DIS module which was used in the late 80s early 90s.
How is the MS controlling fuel and spark, but not controlling the ICM, which creates the spark?
What kind of car is this in, what engine and what alternator? In my 94, the alt turn on wire goes directly to the fuse block (hot in run heater/AC fuse), it's wired that way directly from the factory. I didn't have to use any output from the MS, or change any of the factory wiring harness. Are third gens not like that? I'm pretty sure all the CS130 alternators are internally regulated, so why would you need to add one?
Or am I way off on all of that?
.
James - I think it's cuz the MS won't run the IDI on an ECOtec so you have to use an older ICM and coils. Xardas91 can probably confirm whether or not this is the case. At the one Bash I was at, a guy had an ECOtec Fiero that IIRC he had set up this same way. The MS is controlling spark, it's just using the override on the ICM like other GM's with the DIS.
On the 3rd gens the CS130D alternator wiring runs to the PCM. This allows the PCM to turn the alternator on/off if it sees fit. However, it is still internally regulated. Only reason I suggested using the MS output is so that the MS can turn the alt. off if the engine isn't running.
i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick
James Cahill wrote:Xardas91 wrote:BTW, I'm running a MS2 v3.0 controlling fuel and spark. Ignition is handled by an DIS module which was used in the late 80s early 90s.
How is the MS controlling fuel and spark, but not controlling the ICM, which creates the spark?
What kind of car is this in, what engine and what alternator? In my 94, the alt turn on wire goes directly to the fuse block (hot in run heater/AC fuse), it's wired that way directly from the factory. I didn't have to use any output from the MS, or change any of the factory wiring harness. Are third gens not like that? I'm pretty sure all the CS130 alternators are internally regulated, so why would you need to add one?
Or am I way off on all of that?
.
MS handles the advance. The older ICM's handle the dwell and which coil gets the spark. When I installed my MS2 6 years ago, this is what I had to do as well. If I remember correctly, it was because no MS2 or MS2extra code at the time supported controlling each coil individually through the ICM like the jbody PCM does. I'm sure things have changed since then though.
I have no signiture
Ok, now I get it. When I saw "spark" I wasn't thinking timing, just "spark".
I know the MS3 will do individual coils, and I'm pretty sure I remember someone using MS2extra to do it too. How it was actually wired, I have no idea.
I can agree with using the MS to control the alt to prevent run on, but I think it would be easier to use an ignition hot wire (as long as the fuel pump is still controlled by the MS). Does the PCM control output to prevent over/under voltage, or what?
.
MS2-extra can do individual coils on 4-cylinders but it requires using some of the outputs for the GM stepper motor IAC, so you lose that control, You also have to buy and solder in the coil driver transistors to do this, which means it's not as simple as a reflash of the firmware.
I have no signiture
James Cahill wrote:I can agree with using the MS to control the alt to prevent run on, but I think it would be easier to use an ignition hot wire (as long as the fuel pump is still controlled by the MS). Does the PCM control output to prevent over/under voltage, or what?
.
Doing the igntion wire is pretty simple. Just not a good idea to leave the key on with it not running for real long as the alternator may or may not start smoking. Generally, I think most of us don't do this unless we're troubleshooting something anyways.
I'd like to know what the PCM actually does for sure. I'm only speculating that the only thing is does is keep it off during certain conditions. The internal regulator works fine as far as keeping the voltage steady, so I don't see why you'd wanna use the PCM to try to PWM a device that's trying to do PWM. I never noticed my J doing it, but I know on my Trailblazer, over the winter when the engine is cold, and I start it up in the mornings the voltage will hang real low around 11.xx for about 10-15 seconds. I looked it up and they said the PCM keeps the alternator turned off for a while to keep load off of a cold engine.
i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick
Did some checking on Google. Looks like the alt. runs to the PCM so that the PCM can inhibit operation of the alternator, and also so that the PCM can see the field duty cycle of the alternator (apparently some scan tools can read that PID).
Looks like the newer stuff (mid-late 2000's, probably after the j-body) have a Class 2 serial connection and can do a ton of other things as well. Voltage can drop down as 12.9 volts while driving (just enough to keep the battery up but get better MPG), and crank up the charging rate for a short time during decel to assist in braking. Among other things.
i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick
Whalesac wrote:MS2-extra can do individual coils on 4-cylinders but it requires using some of the outputs for the GM stepper motor IAC, so you lose that control, You also have to buy and solder in the coil driver transistors to do this, which means it's not as simple as a reflash of the firmware.
Yeah. IIRC, he was running a Ford TB, so the lack of IAC control was no issue.
SHOoff wrote:Did some checking on Google. Looks like the alt. runs to the PCM so that the PCM can inhibit operation of the alternator, and also so that the PCM can see the field duty cycle of the alternator (apparently some scan tools can read that PID).
Looks like the newer stuff (mid-late 2000's, probably after the j-body) have a Class 2 serial connection and can do a ton of other things as well. Voltage can drop down as 12.9 volts while driving (just enough to keep the battery up but get better MPG), and crank up the charging rate for a short time during decel to assist in braking. Among other things.
Interesting. This is one of the reasons I like OBD1 or stand alone management.
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I thought it sounds kinda cool. I'm not surprised because the increasing MPG requirements over the years I'm sure they're doing all kinds of little things like this to help get higher numbers. Maybe a pain to try to work with, or around. But on a DD I'd say it's probably a good thing, but we'll see how my tune changes when something on that system breaks and I'm making a post asking "which moron decided to make this junk".
i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick
run the red to a 12V hot in run and you'll be fine.
constant power to the voltage regulator will drain the battery, ask me how I know.
the voltage regulator works on its own, and requires no input from the PCM other than the "turn on" signal, which is merely 12V hot to the red wire on the alternator connector (the small plastic job).
Quote:
constant power to the voltage regulator will drain the battery, ask me how I know
Did you let the smoke out of your alternator like I did?
i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick
