1/2 OT: ALDL schematic to use with my CF29

So a long time ago in a land far away, I researched and built an ALDL cable (info scavenged from all over the net)

Any way, I've never tried it for fear of toasting iether my PC or ECM. I would like any available guru's,IEEE, or car ECM prommers to take a look, and let me know if the schema looks solid.

It pulls power from pins 4 and 7 utilizing blocking diods to prevent them back feeding each other. Other than that it's a darlington arrangement to the ECM ALDL connector.

 

Don't know until now, what ALDL stands for, OBD is better
As protection use a fast Schottky-diode against wrong connection, ZENER-diode against over-voltage and 2 fast fuses less than 100mA.
An better option is an optocoupler to galvanically separate the signals.

 

fuzes on pins 4 and 12?
schottky on + of OBD plug?
I used zener diods on pins 4 and 12 (glass case, copper color w/black stripe)

The above schema should work though? no obvious erros other than protection?

Thank you soo much.

 

InterestingFellow-

What exactly do you want to do with your ALDL connection? Unless you have or feel like researching the interface software to read this low-level datastream, all you'll see are "blink codes" with an LED.

Under any circumstances, here are some links to useful information on ALDL interfacing, assuming you have a source for (or feel like researching the bitstream and writing your own) useful software:

Information on GM's 160 baud ALDL data stream

Reading GM's 160 baud ALDL Data Stream with a Standard PC Serial Port

160 Baud ALDL Hardware Interface

That last link is an outline, schematic and nearly step-by-step instructions on building a known-to-work interface converter.

Good luck,

mnem
"Come & get it, Blinky!"

 

For inquisitive minds.

ALDL

 

Tuner rt pro (and several other programs).
It lets you see just about everything in your ECM and all your sensor readouts. Tuner RT pro even lets you set it up just like an instrument cluster in you dash (so I've been told). Once I get the cable right, I'll start playing with getting software to work.
Under certain conditions (certain OBD1 setups) you can also write data to the prom, like a new fuel map or to ignore....ehm.... egr or other sensor codes.

I sorted out the "ambulance" portion of the electricalreplaced the fuel system, rebuilt the TBI, ported and grooved the heads, valve job, and ground out a section of the intake manifold to increase the HP/torque curve.
Next on the list is a set of 1.6 roller rockers and dual exhaust.
She's gonna run lean if I don't mod the fuel map. I heard I can write the data myself with the correct cable, or spend some odd hundreds of dollars on a preburnt custom prom. This cheap bass turd is gonna try to do it himself (the more difficult and time consuming way).
This is the most in depth work I've done to a motor by myself. It's going in a #6600 1989 G20 full size van, and a a stock 305 would be a pig, so I'm trying to squeeze some hp/mpg out of it (13mpg city, stock). It had a blown head gasket and only 90k miles, and I figured while I was in there, I might as well juice it up a bit.

 

There is also the MEGASQUIRT option for fuel injection if you haven't looked into it.

A old TBI trick use to be to find a wrecked 454 truck 2500 or up and get the throttle body off of it because of the larger injectors and throttle bore size, but you need to do a custom chip for that.

If you increase the fuel pressure you will make the injectors spray more fuel. 5.0 Mustang racers for years have been turning up the stock 19lbs injectors for that reason for years with a adjustable fuel regulator to choke off the amount of returning fuel to the tank.

 

Yeah, I have a 91 astro as well, and swapping out injectors from larger motor is an easy way to get more fuel in there (they come stock with 4.3's).
Crank up the fuel pressure by snapping the little bubble weld inside the stock FPR and tighten that badboy down. once you get it set, you're good to go.
And I've looked into megasquirt. I like it, but I think for the moment I'm gonna play with the stock OBD1 setup. Maybe if I ever build the beast I want to build, I'll use megasquirt. Besides, the proper setup for this van with MSquirt would be just under $500, and I don't know that I'm that attached to it;yet.

This is mostly practice and a learning experience for me. At this point, I want to learn about what I can change, and why I would want to change it. I know I want to play with my fuel map to try to get mpg but also some power when I put the hammer down. stuff like that.

Thanks again ya'll.

 

Yeah, we used to do that on 2-cycle dirt bike heads to improve exhaust scavenging and shape the flame front. You need at least one, maybe 2 more "scores" on the opposite side of the chamber; in order to be most effective, you want your scores to bisect the spark plug. I realize you have nothing there but the head gasket on the milled surface, but even a 1/4" diamond-shaped score in the spark plug boss there would encourage the kind of shaping you're after. Oh, and don't be surprised if you hear it whistling at you when it idles.

mnem
*Head-harded*

 

See, now i'm all irritated.
I grooved the bigger squish area,and looked at that small little flat on the opposite side of the plug and though "it's soo tiny that it doesn't really matter".
Dern it. I already had the heads on before I started this thread. Some felpro haed gaskets, composite type, triple coated with permatex copper coat. Next time, I'll do the other side too. For now, we'll see how it goes. Those grooves are supposed to let the motor run cooler and get more power without suckin more fuel (both due to a quicker and more complete burn).

 

Yeah, I was talking a bit more like this... you certainly don't want to be messing around in your gasket sealing area. As long as you don't cut deep enough to weaken the thread area of the spark plug hole, you'll be good.

As for the diag software, I know that the kind of data monitoring you're looking for is available in OBDII-based vehicles; I don't believe OBD1 has that level of sophistication. I'll be glad to be proven wrong though.

mnem
"ZZZZZT!" is your car's way of saying "Don't touch me there!"

 

yep. that is exactly what i had considered doing. and opted not to because it seemed superfluous. next time i'm workin the heads on an sbc, i'll groove it there too.....

on a great note, I just picked up a set of never installed, powder coated, summit shorty headers for $100 (not the really short baja headers) (dude had them for a gen3 camaro that he blew the engine up in, and then gave up on). I'm gonna refit the stock y pipe until I do dual exhaust and 1.6 rockers.

 

Yeah, well... when you git 'er done, don't ferget to post the 1/4 mi figures for us. :laugh:

mnem
Hey... I had a '56 Nomad that pulled high 12s loaded full of tools.

 

We can go ahead and run it in some of my simulation software if you want too, lol.

 

Mnem'
I live 5 minutes from langly speedway....not that it'll be too impressive, but i wouldn't mind letting her open up wide a few times. vids if i do.

Ador
were you just havin fun with me? I just started looking into the whole tuning thing and have (almost) nooooooooo idea what i'm doing there.

who here is on some hotrod or chevy or whatever site. i like knowing people who know me (at least somewhat) rather than being a noob (again) on some new site.

 

No I do have simulation software for cars. You need a list of what I have?