DL1 RPM Issues

jvollrath
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DL1 RPM Issues

Postby jvollrath » Mon Feb 28, 2011 12:40 am

Hello,
I'm on a college FSAE team and we're trying to get our DL1 to log RPM data. I have a test setup with a small motor that simulates the flywheel sensor. This signal tells my ECM to send the signal to the spark plugs. In the test setup I have taken the spark plug signals in inputted them into the DL1's rL signal input. However, the DL1 doesn't record any RPM data. After that, I tried putting the spark signal into rH, but that didn't work either.

Any ideas? Thanks for any help

-John

osborni
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Postby osborni » Mon Feb 28, 2011 4:27 pm

I would suggest hooking up an oscilloscope to the spark plug signal to ensure it's within the specs RT provides. 5-15 volts, square wave, ~50% duty cycle.

Fly sensors are normally variable inductance, not hall effect, so the signal is much dirtier then a hall effect.

I'm not an expert at engine management, but it would be reasonable to have the injector signal be a cleaner signal than the spark plug. Even if the spark (coil on plug) is a trigger signal from the ECU, there's a lot of noise going on in that package.

I'm surprised that you ECU doesn't have a dedicated RPM output signal.

Also ensure that your DL1 has been set up to record RPM.
Last edited by osborni on Mon Feb 28, 2011 4:29 pm, edited 1 time in total.
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Turby
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Postby Turby » Tue Mar 01, 2011 1:17 pm

A lot of ECU's turn off injectors on the overrun to save fuel... hence you will loose the rpm signal. The same can happen for signal sent to the coil(s).

jvollrath
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Postby jvollrath » Tue Mar 01, 2011 6:05 pm

We have a custom ECM developed by a few team members 4 years ago, so that's what we use.

When you say enable the DL1 for RPM data collection, what does this entail? I remember selecting/deselecting a checkbox in the configuration for the DL1, but is there more to it than that?

I will try to pull the injector signal from the ECM and see if that works. Your theory may have some substance to it because occasionally my tests would show RPM data (albeit false data), and most of the time it would show 0. Maybe the occasional RPM data was from the noisey signal finally meeting a threshold.

Thanks for your help. I'll let you know how it goes in a day or two.

osborni
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Postby osborni » Tue Mar 01, 2011 6:36 pm

Use the DL1 config utility to enable data logging for RPM. save to CF card per instructions then boot up the DL1 with the CF card installed.

You're at a university, they should have a scope someplace. :) It's faster and better then using the DL1 to figure it out.

So much so, that I'm seriously considering buying my own portable one for situations just like this.
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Rob Stevens
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Postby Rob Stevens » Wed Mar 02, 2011 11:25 am

I have a http://www.picotech.com/oscilloscope.htm turns your pc into an oscilloscope very handy, they have some very affordable models.

DMKMM
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Postby DMKMM » Thu Mar 03, 2011 1:54 pm

Rob Stevens wrote:I have a http://www.picotech.com/oscilloscope.htm turns your pc into an oscilloscope very handy, they have some very affordable models.


thats cool, i want one

jvollrath
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Postby jvollrath » Fri Mar 04, 2011 5:25 am

PS - I have a scope at my workstation. I scoped the spark signal before, but never really paid attention to its amount of noise. This time I will, and I'll compare it to the injector signal's noise.

osborni
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Postby osborni » Fri Mar 04, 2011 2:41 pm

If it's too noisy, you could always give a small project to a EE on the team. A variable reluctance to hall effect converter and use a standard off the shelf crank position sensor to drive RPM to the DL1. Sounds like a good sophomore/junior level project.
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jvollrath
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Postby jvollrath » Tue Mar 15, 2011 2:41 am

Hey guys,

So I've tried your suggestion to use the injector signal. I can confirm that the signal is much cleaner than the spark signal.

It is still not reading any RPM data. I have made sure to Disable both RPM sampling rates in the DL1 configuration. Here is how I currently have it set up:
-rG connected to battery voltage
-rL connected to injector signal (it switches to gnd)

When I scope the injector signal with respect to 12v WITHOUT having the gnd and signal plugged into the DL1, the scope reads a relatively good square wave. However, once I plug the gnd and signal into the DL1, the scope reads a flat line at 12v. There is no wave, just a line.

I don't understand what the DL1's circuitry is doing. Does anyone have advice on this?

jvollrath
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Postby jvollrath » Tue Mar 15, 2011 5:50 am

Another update:

My friend and I tried a whole bunch of configurations. One of them produced some data collection, although it seems unintelligible. We tried: not disabling RPM in DL1 config, hooking up the injector signal to rH, and hooking ground to rG. This produced some data, but I don't see how it could be correct.

I would really appreciate some definitive instructions to getting this DL1 to log RPM. I've tried a whole number of combinations of settings/inputs, and nothing has worked. Please don't take anything for granted -- there must be something simple that we don't know.

So for clarification, here are the inputs I wish to use:
Injector signal (switches to gnd)

I don't know whether to disable RPM sampling in the DL1 config or not for this setup. Also, I don't know whether to use rL or rH. In the case of using rL, do I have to hook up any gnd to rG or the analog GND? In the case of using rH, do I hook up gnd or 12v to rG (since the injector signal switches to gnd)?

Thanks for all your help,
John

Rob Stevens
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Postby Rob Stevens » Tue Mar 15, 2011 10:58 am

Just connect the following

+12v to +12v on DL1 (with a fuse!)
Ground to GND on DL1
Injector signal to rL on DL1

Ensure that the DL1 is configured to its default condition as found when you fire up the configuration software.

Check using the lite monitor that its working.

If you still can't make it work the DL1 may be faulty?

jvollrath
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Postby jvollrath » Fri Mar 18, 2011 5:17 am

How do I make Lite Monitor show RPM data? It does not show that rL signal data (by default).

Rob Stevens
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Postby Rob Stevens » Sun Mar 20, 2011 8:31 am

My one does, so sorry can't help!


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