HydroProp Project

[jankovig]

Today hasn't been a very good day, after spending the past days working on code to read pulse widths and translate them into frequency and duty cycle I hit a wall today when trying to interface with my truck.

The wires to the fuel injector are reported by my multimeter to be operating at a hz rate which is what I would expect in relation to RPM, however, the meter reports 99% to 100% duty cycle which is obviously false for one injector.

I went ahead and interfaced to my microcontroller and wrote some code to analyse the signal and feed back to a laptop, however, from all points it appears to the microcontroller as if the pulse never stops.

I suppose I will think on this tonight and try again tomorrow. What I really need is a proper oscilloscope to analyse the signals going to the fuel injector, but they are effing expensive and my PC based scope just doesn't seem to be cutting it.

Russ.

Hi new guy here. Electronics/Electrical Engineer by schooling/trade who recently got VERY interested in the whole HHO side of things and would like to offer help.
When using the multimeter to measure the PWM signal, all you're going to end up with is the DC component of the PWM. In other words just plain voltage. To properly evaluate the PWM signal, you need to use an oscilloscope. From my experience, the most you're going to see on the PWM frequency is 100-200 hertz. These days you can rent an oscilloscope. You wouldn't need much. 20MHz, 2-channel would be fine.

[Painless]

Hi Jankovig,

Unfortunately, it was much worse than just my fuel injector. I replaced the injector only to find that the original was fine and am now looking at finding the money to buy a new ECU for my truck.

Not very happy at all. This project is definitely on hold until I get my truck sorted. It is barely drivable at the moment, just limited to 2500 rpm and lumpy / erratic.

Russ.

[jankovig]

Here's a stupid question, but did you try resetting your ECU by disconnecting the battery? I know it's a long shot, but it might help.
Any time you want to do any type of voltage/freq. measurements that involve engine ECU, you want to use good quality high impedance probes. Low quality meters just don't have a high enough input impedance and end up loading the ECU output to the point where it can't source any more current it just burns out.

[Painless]

That was the first thing I tried, I've even removed and opened up the ECU to see if there are any visually blown components.

I've since learnt the lesson of high impedance equipment as you can imagine, shutting the proverbial barn door after the horse has bolted, so the speak.

Russ.

[Vulture]

Painless, you seem to be much farther along on an idea I've been working on as well. My whole purpose of computer control was for safety, if any one part failed the whole system shut off. I was planning on using an Arduino chip, I'll have to check out the one you're using.

As a possible solution to your injector pulse feed, have you thought about tapping straight into the ECM via the OBDII port? The amount of data you can read is amazing, more than those dinky <$200 scanners you buy at the parts stores. Depending on the vehicle, you should be able to read injector pulses, MAF, O2, EGT (if so equipped), timing, everything else you need. Depending on how gung-ho you get, and your programming skills, you could do all of the necessary data manipulation right in the ECM without the need for EFIEs and the like. The OBDII standard is publicly available.