I should let the group know that I ordered a new RTR cable from DIY and will plug it all in and test it again as soon as it arrives. That might actually happen today as it was sent from Georgia yesterday and sometimes the mail is that fast.

He also sent me an e-mail describing how to check the ECU to make sure the jumpers are set up right for VR read. Thanks Matt.

It still seems odd to me that the ECU can read a square wave signal and a sine wave signal without making any software changes to indicate the different input. The trigger type is listed as basic trigger for both. Am I still missing something here Matt?

Sam

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The ECU has an adjustable trigger voltage. If it's set to 200 mV, for example, it will trigger when a sine wave signal goes over that point - and if you feed the ECU a square wave instead, since the square wave makes a jump from zero to 12 volts, that also triggers it. The MS2 does not need the voltage to go negative in order to trigger off a sine wave, unlike some setups.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

Matt, Do I have to set that trigger voltage somewhere? Maybe that is why it will not read the sine wave now?

Sam

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I got the new cable, and got it installed last night. Why do things like that always take 3 times as long as you think they should? It took me one episode of The Office, one episode of House (all reruns on Fox, which is the only channel I get in the garage) and half an episode of The Good Guys, to get a simple cable run. Two hours?

Anyway, the ECU still cannot read the VR pickup. It runs fine with the square wave tach signal, but not with the sine wave VR output. But I know the VR signal is fine since the MSD box sees it fine. So I will open the box and check the circuits as I was instructed to do by Matt. More on that later.


I suspect the new cable will enable the IAC circuits, which I am pretty sure Lou did not include in his assembly of the older cable, since IAC was not available when he made it. I left the IAC stepper motors off for testing at my local garage yesterday. So I will know if they are any good. Then, to get the IAC working, all I have to do is figure out how to calibrate the stepper motor and software. (He says jokingly)

Sam

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