What Do I Need

[maxed_out]

Hey everybody. My apologies if this has been written about before. Just want to ask what do I need to hook up my laptop up to my 91LS and start reading codes and looking at performance data. I know I can use a paperclip and do the count the flashes thing. I'm interested in something more. I'm not trying to fix any problem right now but I think its cool that some of you can do this to look at some of the data thats available. You never know when something like this can be helpful.

So what's possible and how can it be done?

Maxed

[Econ]

Facinating idea. But I have no idea how to actually pull the diagnostic information from the computer. I'm not even sure that you could get it done.

You'd need:

Custom designed cable. Parallel cables are the easiest to use because they have 25 pins to use. You cut off the female end (I think...) and start to figure out how to make an attachment that will plug into the diagnostics port under the drivers side dash.

Custom program that will read voltage coming in over each pin in the cable. This is probably easier than it sounds, just a little practice to get the interface programming right.

A source for the information related to the diagnostics information you're receiving. Those pulses and voltage variances are great, but they don't mean a whole lot. You need to know what pins to send current down, how much, and for how long. Plus you need to know what pins the car will send current over to send the info.

The problem with the project is that the computer system on the 1991 LS400 may not tell you a whole lot compared to the OBD-II system currently found on cars (I don't even know if it has an OBD-I system or not... that could probably be figured out easily, though). Even if you get something hooked up, it's likely to be more of a technological feat than a productive tool.

What are you looking to do with the scanning tool? Monitor A/F ratios and the like?

[maxed_out]

Hey Econ...looks like a project I'll try to take on. I'm not going to use it for anything other than to share gory details with all yous guys. Maybe it can become a troubleshooting/diagnostic tool?

Sure would be nice to see whats going on as you go down the road.

How would you use it?

[914lps]

I know on the 91 it is OBD1

If you get this thing done let me know. I habve a lap top and a 91 LS400. I would love to be able to read the computer (The one in the car not the lap top). And with it costing at least $50.00 to have it read, I would even pay out some bucks to be able to read the codes myself.

[92Lex]

They have wireless programs with adaptors for most vehicles..it just depends on how much you're willing to spend. Take a look at the MODIS...has a lab scope, code reader, wireless capabilities, DVOM, troubleshooter and a few other things on it...I'm about to pick up this bad boy next week..I'm going to be $8k poorer.

[Econ]

Yeah, I was intrigued by the idea and started to browse through the sources I could find via Google - holy cow, there are some pricey scanners out there (made me droooooool, none the less).

What would I use the scanner for? Well, depending on what kind of information I could get from the OBD, air/fuel ratios are always a plus but I would definitely want to see narrow band measurements - along with how the electrical system is doing (output from alt, etc.). Otherwise I can't think of much. I have had so few problems with this car that I want to diagnose that I can't come up with much right now.

However, if I had the ability to mess with the fuel maps in the ECU, I'd sign on in a second. They have a utility called TwEECR (I think, I can't rightly remember) that I have heard about people using on Mustangs. It allows them to alter the fuel maps in the ECU while monitoring some A/F data without having to understand the native ECU programming. Sounds very exciting and definitely a quick way to optimize. (Or, if you're not careful, destroy)

[maxed_out]

Hey, looks like it has to come off the front burner for me...got a new job thats going to require lots of attention right now. If anybody moves the laptop idea along please share. I was hoping to do something we all could replicate, use as a tool to share details and be affordable.

Thanks for all the posts so far.