realtime monitoring tools for pre-obd2 cars

[monroe74]

"Possibly a 12V meter would do if you only expect to see 80% duty cycle"

On my car (VX) the maximum duty cycle (WOT, redline) seems to be about 60%. I think I've read in a couple of places that injectors typically have a lot of headroom, in this regard. FWIW.

And if whatever you're designing is intended to be used by people who are into high FE, then odds are that they will never see the maximum duty cycle that their injectors are capable of.

[fumesucker]

If you already have a laptop that isn't being used much I have found a possible solution.

Someone already wrote a Java app that will use the two channel sound card on a laptop to compute fuel economy using injector pulse width/frequency on one channel and speed on the other channel.

The thread with extremely simple schematics and source code as well as a binary is at this url:

http://www.gassavers.org/showthread.php?t=4250&page=2

[theholycow]

I bought the $33 DMM with dwell from HF, and I'm very impressed. It's not only the most substantial item I've ever bought from HF, it's the most substantial anything I've gotten from anywhere for $33, as well as being the most substantial automotive electronic item I've ever bought.

It comes in a nice case that houses all the included accessories, and has a thick rubber glove that goes on the bottom of it to protect it from impacts and greasy surfaces. It comes ready to use with a battery installed. The tach and dwell functions have settings for 3, 4, 5, 6, and 8 cylinders, and it has a transistor testor built-in too. I'd say I can't wait to get out and try it but I'm feeling lazy today, as I do every day, so I think I'll procrastinate. It can measure DC amperage up to 10 amps, which is awesome.

While I was there I also bought a mechanic's stethoscope for $3, so I won't be using a short piece of rubber hose to try to listen to different pieces of my engine.

Other stuff I bought that I really don't need but I couldn't resist: a small handheld self-igniting torch for $5, a LED hitch cover for $8 (which will certainly get me rear-ended, as every hitch cover I've ever installed has done ), and a clamp-on DMM that can inductively measure up to 1000 AC amps which I've wanted forever but couldn't bring myself to spend $20 on -- it was down to $10.

That was $60 that I don't have and shouldn't have spent, but I can tell myself that I'll eventually save $60 in gas because I bought that $33 meter.

[Snax]

Originally Posted by fumesucker

If you already have a laptop that isn't being used much I have found a possible solution.

Someone already wrote a Java app that will use the two channel sound card on a laptop to compute fuel economy using injector pulse width/frequency on one channel and speed on the other channel.

The thread with extremely simple schematics and source code as well as a binary is at this url:

http://www.gassavers.org/showthread.php?t=4250&page=2

The sad thing is that I probably read every single post in that thread last year, but I didn't have and OBD1 car at the time, so it all got flushed out of my memory that skewbe had done the work for us on that.

But now, the Escort needs a meter!

[fumesucker]

Originally Posted by Snax

The sad thing is that I probably read every single post in that thread last year, but I didn't have and OBD1 car at the time, so it all got flushed out of my memory that skewbe had done the work for us on that.

But now, the Escort needs a meter!

I've found it worthwhile to dig for stuff pretty hard before re-inventing the wheel.

It's one of those apps where you slap yourself and say, why didn't I think of that?

All hail skewbe for a brilliant app..

[monroe74]

Originally Posted by theholycow

I bought the $33 DMM with dwell from HF, and I'm very impressed. It's not only the most substantial item I've ever bought from HF, it's the most substantial anything I've gotten from anywhere for $33, as well as being the most substantial automotive electronic item I've ever bought.

All of the above is also true for me.

One minor thing to be aware of is that the impedance is only 1 megohm. More expensive meters have 10 megohm, I think. Some people claim this matters, for certain applications, but I have a feeling it will never make a difference, in my situation.

While I was there I also bought a mechanic's stethoscope for $3, so I won't be using a short piece of rubber hose to try to listen to different pieces of my engine.

The trick I like is to use a very long screwdriver, and press the top of the handle against the bone in front of my ear. Works fine. In a pinch I've also used a jack handle.

Other stuff I bought that I really don't need but I couldn't resist

I got sucked in by the $5 LED flashlight (my very first LED flashlight), the $11 timing light, and the $5 digital tire-tread depth gauge. That last item is nicely made, and very cool. Because it will let me monitor tread wear in a very precise way, it will be easier for me to make sense of what's going on with things like wheel alignment, tire pressure and rotation. Tires aren't cheap; I want to get the most out of them.

I intend to also use it for various other measurements, like brake pads.

[theholycow]

Originally Posted by monroe74

$5 digital tire-tread depth gauge. That last item is nicely made, and very cool. Because it will let me monitor tread wear in a very precise way, it will be easier for me to make sense of what's going on with things like wheel alignment, tire pressure and rotation. Tires aren't cheap; I want to get the most out of them.

I intend to also use it for various other measurements, like brake pads.

I didn't notice that there. What's the resolution on it?

I have a digital caliper whose end acts as a depth gauge, which I got for under $20 some years ago on eBay. They have them at HF for $12 or $14 or so. They're good to 1/1000 of an inch or some such crazy number. Lately I've been planning to use it to see if my tires are still wearing evenly...

[monroe74]

Originally Posted by theholycow

I didn't notice that there.

http://www.harborfreight.com/cpi/cta...emnumber=95381

What's the resolution on it?

They're not telling. But when you set it to mm, it reads two decimal places. So, for example, when I just measured the thickness of the quarter in my pocket, it said 1.64 mm. The right answer is 1.75. The difference is 6%. Close enough, considering that the coin is worn.

Then I measured again, and asked for inches. The answer was 0.061". But 1.64mm is equal to 0.065". But that's close enough.

By the way, the manual says the product has a computer interface. But it doesn't.

I have a digital caliper ... They have them at HF for $12 or $14 or so

I think that's basically the same product I have, except in different packaging.

[theholycow]

That tire depth gauge is definitely the same electronic bit, just less body. Here's a 4" digital caliper for $15:
http://www.harborfreight.com/cpi/cta...emnumber=47256
There's a plastic 6" digital caliper for $10 but it appears to be missing the depth gauge:
http://www.harborfreight.com/cpi/cta...emnumber=93293

[slurp812]

Originally Posted by RoadWarrior

Thinking about it, you could probably rig a voltmeter through a capacitor to give you injector pulse width duration, would probably only be accurate to within a percent or two, but would be a good visual indication.

Yea! Something analog would be cheap and easy!