Hello, i have been working on a way to put a GM HEI module in place of a stock toyota one. ive gotten very close to figuring it out but i need to figure out some way to make a digital pulse into a analog one (I think). In the pic below i need it to go from the one on the left to the one on the right if you where watching them on a scope. Thanks.

http://members.isp01.net/trailrunner/WaveForm.bmp

btt

I'm no electrical guru but since you're btt-ing here goes. That analog curve on the right looks like a standard equation curve with a peak at the level of the digital signal - don't they make transistors you can wire in the circuit to do those types of conversions? I'd say take the charts to a Radio Shack along with the other specs and buy the transistor they recommend. Worst case you're out $1.79.

Originally posted by TrailRunner
Hello, i have been working on a way to put a GM HEI module in place of a stock toyota one. ive gotten very close to figuring it out but i need to figure out some way to make a digital pulse into a analog one (I think). In the pic below i need it to go from the one on the left to the one on the right if you where watching them on a scope. Thanks

That is easily done with a simple RC circuit. Put a resistor in series than a cap from the output of the resistor to ground. I can't really give you details on the RC values without knowing the time scale and the load resistance, but start with the R value in the 1K to 10K range.....
(Here is a web page that will help you calculate values required: http://www.tpub.com/neets/book2/3d.htm - Note there example excludes the effect of load resistance.)

Now, with that said, I really don't see why you would need to do this. All ignition systems will be looking for a single pulse (essentially Digital) and will usually use a comparator on the incoming signal and as soon as the level gets above a certain voltage reference it will trigger the circuit. So basically the internals of the box will make the right signal look like the left!

If you can't get it to work as is, I would be more concerned with checking pulse width and polarity (rising edge or trailing edge trigger). Another note, from what I remember of my old Cutlass with HEI, it used a variable reluctance pickup (magnetic) to trigger the module. I don't know what was in the Toy, but you may have an incompatibility in the type of pickup signals you are using. A magnetic pickup (coil) is current triggered, photo or Hall effect is a voltage signal.

I don't know if I've helped or hurt, but maybe that'll help... :rasta:

Originally posted by TrailRunner
Hello, i have been working on a way to put a GM HEI module in place of a stock toyota one.

Could you run this by use once again?

I fully understand using the GM unit ($20) versus the toyota ($250) unit.

Which GM module. The "Crab" is a four connector one shaped like a little crab. Other ones have additional leads, and features.

Are you using a STOCK Toyota distributor? If so what year/model... i.e. point, early '70s trigger, later '70's trigger. If you have a 3FE with a optowheel... uh, all bets are off!


Tom :usa:

There was a post in the toyota forum about this. Id link it but im stupied, search under igniter then look at seabasses post.
Supposed to only work on carb trucks.

Originally posted by 4runnerx2
There was a post in the toyota forum about this. Id link it but im stupied, search under igniter then look at seabasses post.
Supposed to only work on carb trucks.

You wouldn't be talkin about this one would you??

Toyota forum GM HEI thread. (http://www.pirate4x4.com/forum/showthread.php?s=&threadid=25847&highlight=gm+hei)

I dont know, maybe it'll help:confused: :confused:

What module are you trying to use? If it's a 5 or 7 pin mod you will have to use an ECM that controls the dwell, and that would be made by GM.

That being said, I have suggessfully triggered a 7 pin module with a simple $30 pickup coil/crank trigger that fits a 90's GM V6... Maybe you want to look into that as an alternative.

I know nothing about Toy ignition, but it's possible that it will work fine with the HEI module, they don't seem to be too picky about the trigger signal.

So *exactly* what are you trying to do?

Squash

You two newbies :flipoff: you have no idea what i am talking about. you can use a carbed Hei module on a 22re. Well chevy made a Hei module that is computer controlled and it looks like you can replace the toyta igniter with the computer controled HEI module. now as far as the voltage, resistance, current etc i have no idea about. but thatnks. later i will post a few pictures of what im tring to do. Thanks.

Does your toyota control the timing/advance/dwell on the igintion system? I know about the GM stuff, it's cake. Toy stuff is, well, foreign!

Squash

yes the toyota ECU does adjust the timing dwell and advance. a alternating signal comes to the igniter where a wave form converter turns the signal into a digital pulse where it goes to the computer the computer changes the timing and then it sends the modified timing pulse back to the module. from there it goes to the transister which switchs the coil. So far this is exactly how a GM 7 pin HEI module works. Both the toyota Igniter and the GM Hei module have a circuit built in to allow base timing to go to the transister when cranking, the GM Hei module uses a 5v referance to switch to the modified timing signal and the toyota igniter uses the ECU to determine when the engine has started, it does this by not providing a modified timing signal to the igniter and using the base timing to fire the coil. any way i think i may have away around that but what i really need to know is that the toyota ECU needs a pulse sent to it like i drew above when ever the coil fires. i dont know if i could just send the computer a digital signal or not but i think i have most of this figures out. BTW i am including a picture of the Toyota igniter system. Thanks.
http://members.isp01.net/trailrunner/Ignition.bmp

OK, it takes some experimentation to do this kind of thing. I don't really think it's as simple as you want it to be, but in order to get beyond that you really need to scope it all out and figure out what it really wants. Darn near anything will trigger a GM module, that's what i've found. It's not horribly picky. That's all I can offer.

Squash

if you are trying to make a digital pause into an analog pulse use a D.A.C digital to analog converter chip to do it

Originally posted by TrailRunner
You two newbies :flipoff: you have no idea what i am talking about. you can use a carbed Hei module on a 22re.
Gee, I wasn't the :rainbow: :flipoff2: who posted a TECH question in the General area while only using "on my Toyota!" Fawking mind reader I'm not. Some clueless idiot using a GM module on my Land Cruiser, I am! I'm a newbie on this forum, so I guess I need to go post 500 post in chit chat before you'd even explain what you're tryng to do! :D

Tom :usa:

Originally posted by roundrocktom

Gee, I was the :rainbow: :flipoff2: who posted a TECH question in the General area while only using "on my Toyota!" Fawking mind reader I'm not. Some clueless idiot using a GM module on my Land Cruiser, I am! I'm a newbie on this forum, so I guess I need to go post 500 post in chit chat before you'd even explain what you're tryng to do! :D

Tom :usa:

Thanks!

Actually i wasnt asking how to put a GM Computer Controlled HEI module on my 22re i was asking how to convert a digital signal into a analog signal. So this question was a valid General 4x4 Tech question. I have no dought that you put a GM HEI module on your crusier, its been done and it works.

Originally posted by TrailRunner


i was asking how to convert a digital signal into a analog signal.


All okcrawler already commented: resistor & capacitor (i.e. low pass filter) is all that is needed to get a pulse signal to look like a rising waveform as in your first post. :D

No comment on if you need that or not. Have you figured out that the GM 8 lead module needs a signal from the ECU, compared to the OEM Toyota module that has it's own frequency comparator circuitry built in? Ya, The Toyota ECU doesn't supply a signal needed by the GM Module, but I'm sure you'll figure something out. :D After all, I'm just a fawking newbie. :flipoff:

Tom :usa:

I'm afraid I've lost track of exactly what you are trying to do. I am guessing that you need to generate the IGf signal for your ECM... From the drawing it shows this signal comes from the coil drive then goes thru a "signal generation" circuit and the output is the R-C waveform shown. The major concern here is that you do NOT connect the coil drive directly back to the computer. When the coil is fired, there is a spike in excess of 100V on that side of the coil, and is likely to damage your ECM. A simple RC circuit should be sufficient to dampen this. In fact, a Samurai has just such an external 'box' (about the sized of a relay) for that purpose. If you can wait 'till I get home tonight, I will check the book and see if it gives any details (like the R-C values).

hey tom :flipoff: right back at you, i was going to use the signal from the AFM that turns the fuel pump on and off to trigger when to get off base timing. if that wont work i will figure out something. Mark thank you for all the technical advise you have given me. Im just gettin gthe details for it right now so if mine does go out or some one i knows does we can try this before we get raped for a new igniter. Thanks.

You dont need to covert the signal. the Ecu just looks for the Hz. of the ac signal. Search under ignitor in the Toyota section. There are pics, diagrams, everything.