Live engine data on PC for less than $100


Old 04-29-10, 06:04 AM
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Join Date: Oct 2008
Posts: 1,312
Live engine data on PC for less than $100

I've been wanting to own an electronic tool to see "live engine data" on my GMC truck for quite some time now, but the pro tools to do this cost upwards of $3000!

And there is free software and wires you can buy or make to do this with a PC, but I did not own a laptop before. (I'm not going to drag my desktop PC outside to my truck!)

Well I got lucky and found 3 broken laptops at a yard sale for $10 for all 3. Then was able to get one of them running by swapping parts and fixing a few things.

The free software is called WinALDL and note this is for older GM "OBD I" vehicles only and only those listed on the web site. (After 1996, everything changed to "OBD II". However there is different PC software available for that, see below...)

Here is the free WinALDL software info as well as the info on cables...
WinALDL - 160 baud ALDL reader

The laptop I now have does not have a "serial connection" which is needed for this old software. They make USB to serial adapters, however many of these do not work (as I learned by buying one such adapter from Staples for $40 which did not work).

I found a USB to serial adapter at the following link which does work and it is only $17...
Parallax USB to Serial (RS-232) Adapter with Cable

So I took my new laptop out to my truck, connected the cables, clicked on WinALDL, and presto! I had live engine data!

I can now see all the sensor data the engine computer is seeing (much quicker than testing each thing with a multimeter). This also shows diagnostic codes, engine temperature, rpms, speed if you are driving, O2, rich/lean, etc. Even shows if the A/C is on or not! (Everything the engine computer would "see".)

Here is all the data WinALDL shows (I have not read through this yet as I have been busy getting this all working)...
WinALDL version history

My truck is running fine right now, so now that I have this working, I'll next learn how to use the software - see if I can save the data. Then save a "snapshot" of all the sensor values with the engine cold and then warm. And also note the outside temperature. Then if I have a problem with the truck in the future, I'll be able to just quickly see what reading(s) is different from when it was running ok.

FYI - I don't own an OBD II vehicle, so have not looked much for PC software for the newer vehicles. But following is one called EFILive which you have to pay for. I don't know if you have to also buy their electronic interface module or not?
EFILive Web Site

But I would think there would be other PC software out there for OBD II. And I would think this would be better than buying a "scan tool". You could always update the software in the PC and would only be paying for the software/cable and not an electronic "gizmo", then be at the mercy of the company for software updates.

Here is a google search for "obd II" software...

Use "free software" at your own risk of course, but here is the same search with the word free included...

Right off the bat I see the following called "opendiag". The word "open" means free and many times better quality than what is for sale. Then I followed that to "" which has some very good quality "open" software. I have not read the following and you can follow the links from here if interested...
Freediag - Vehicle Diagnostic Suite

More OBD II software I found at sourceforge... Software Search

Main sourceforge URL... Find and Develop Open Source Software
Sponsored Links
Old 05-03-10, 03:27 PM
Join Date: Jul 2009
Location: Washington State
Posts: 312
Beer 4U2 sounds good Bill Don't do to much OBD1 stuff and more but sent you a PM for some Cheep OBD2 hardware and software package in case you need to "upgrade" in the Future.
Old 05-03-10, 04:09 PM
Unclediezel's Avatar
Join Date: Dec 2006
Location: Northeastern PA.
Posts: 2,230
By no means will I try to "Burst Your Bubble".....

Just keep in mind...Most PCM's use preset values during limp -in mode. Not a problem , provided that you discard the Idea that this is an acceptable substitute for a multimeter. Data stream and "Real -world" voltages can vary GREATLY between a Laptop datastream and actual "Intrusive " multimeter testing.

Someone here (I'm thinking it was you Bill) mentioned how a knowledge of what and how things do their thing is essential to picking out who isnt doing their job, or not doing it corrrectly....

Between you and a PCM, There is almost always a difference of opinion. Just Food for thought.
Old 05-03-10, 07:00 PM
Join Date: Jul 2009
Location: Washington State
Posts: 312
Copy that Unc never liked dealing with OBD1 much not really to specific in info.,always just general locations in where the problem might be or one of a half a dozen related but not monitored systems.LOL But you already knew that.
Old 05-04-10, 01:10 AM
Join Date: May 2010
Location: USA
Posts: 1
Very intresting information.
Old 05-05-10, 08:27 AM
Thread Starter
Join Date: Oct 2008
Posts: 1,312
Originally Posted by Unclediezel View Post
..Just keep in mind...Most PCM's use preset values during limp -in mode...
Thank you, that is VERY good to know!

As to limp home mode, I've looked high and low for more information on this, but the vehicle manufacturer's keep their engine computer software a "secret". There is very little information about this in the factory service manuals I have for my older (90's) vehicles. And it is buried and just a brief mention about one or two diagnostic codes doing this.

What they need is a nice little one page table showing the codes which do this and under what circumstances the engine computer will go into limp home mode. And it would also be helpful to mention that you are not going to get the correct readings of the sensors until you delete the code if that is the case.

This is a pet peeve of mine! If you are going to expect someone to fix something, they need to have access to documentation which explains how it works! If you know how something works, how it *should* work, then you will better be able to find the trouble.

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