Hello all, I was somewhat active on the old GM EFI and DIYEFI newsgroups years ago. Yes, I'm older than a few of you and have now proven it....
I built an ALDL interface cable back when laptops actually had serial interfaces. It worked very well for my purposes ( a then-stock 4.3L 1989 S10 Blazer) and was mostly built for bragging rights. While I intended to do some ECM tweaking, it quickly became apparent I had no business messing with that in the truck I was driving every day to work.
That was something like 20 years ago. Now the same truck has been modified slightly (ok, the frame is mostly stock, the body is stock, and it still has the same transfer case.... everything else, however, has been messed with). SOA, Dana 44 axles front and rear, springover lift, hydroboost, a replacement 700R4 (soon to be upgraded).... and a 96 GM Performance Gen II 5.7L V8. I'd intended to use the original ECM, but a good friend on another forum donated a raft of parts to the project- including a pulled ECU that plugged right into the same harness as my 1227747 V6 ECM and already had the MEMCAL and proper chip for an auto 5.7 V8.
I've got the truck running, just not well. I am having driveability concerns that appear to come and go- starts up fine, and after the 30 second idle-up it starts to exhibit a stumble in the idle... once things have warmed up the stumble is REALLY apparent.
I had this issue upon initial build (truck has been down for a year due to the need to go Springover up front and ensuing domino effect with shocks, steerage, etc).... I figured it to be the IAC. Pulled one off my old 4.3 as I knew it was recently replaced- and things appeared to be fine. Now it's a year later and the issue is back.
I thought I'd found the issue when discussing matters with same friend, I mentioned the VSS needed to be extended as I'd noticed the wire hanging off the tailshaft of the tcase. DUH, he said- that's required input for the IAC, that'll fix the issue. I investigated and found that I'd never dropped the harness side of that connection down from the ziptie I'd used to secure things on initial build- ie, it had never been hooked up and the truck ran fine once upon a time. Extended the wires (solder, heatshrink, and quality tape and loom, so there's no shorts causing this- I solder and build my electrical to MilSpec), reattached and the problem persists.
At this point instead of approaching the issue with the Parts Shotgun (a few hundred bucks of new parts at the shop, to no avail), I want data...
At present I am not looking to burn chips. This isn't a race car, and I don't know what I'm doing there. I just need to get the data pulling, and prefer to do it without a special cable.
To that end I came across info last year on using an Arduino MAX232 USB to (TTL?) to interface with the ALDL wires A and E (GND and 160-baud data). I have the parts needed, soldered the TXD and RXD wires together, tested by attaching the MAX232 GND to the ALDL Gnd and the TXT/RXD combined to pin E (160 baud data).... and nothing worked (using Tunerpro, not convinced I'm doing THAT right either. I'm an IT guy and I do all manner of complicated things- but Tunerpro is even moreso!). I suspect it may be the lack of a 1KOhm resistor and a diode for the RXD/TXD wires respectively. I do recall having to use those to get the old serial interface to WinALDL working. Problem- there's nowhere in town to grab these bits now, as Radio Shack is no longer in the area. I foresee a weekend spent raping old electronic bits laying about the house of resistors and diodes....
If anyone can advise me on a way to use the above equipment to speak to TunerPro to datalog as I testdrive the truck, I'd be forever grateful. As it is, I have not yet paid for Tunerpro, though I do certainly intend to do so once it's done something useful for me. (ok, ok, also, no sooner than next Friday- just started a new job and Friday is our first full payday- I'm broke as a joke at present!)
I realize there are prefab cables that I can buy. However, while that may well be the solution for most, I can't go that route- I'm VERY much a hands-on guy (I've built this truck myself, with some wonderful advice and tips from friends). I also am able to solder, etch PC boards, etc- pretty much everything but code. I'd rather not get into that- I'm doing this for relaxation and accomplishment, if I have to learn to code as well it becomes too much like a day at work (and I have plenty along that line I have to do for my career, so no thanks!). When I'm at the point I'm receiving data realtime, I'd like to work the solution underdash so that I can simply plug a USB cable under the dash and into a laptop on a stand in the passenger seat and do what I need to do. When that's done, unplug the USB and carry the USB cable and the laptop in the house- the rest of it stays in the truck, hardwired in.
Future expansion probably holds a replacement ECM that can control fans, run a WBO2, etc- but that's a far part down the road... I need to get the old beast running and getting me to the new job, ASAP.
Also, HI, TOM! :)
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