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DB2SR - winter project turns into lockdown project
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hindsight



Joined: 13 Feb 2010
Posts: 126
Location: Central Scotland

PostPosted: Sat Mar 13, 2021 6:50 pm    Post subject: Reply with quote

Updated board now fully built - to my relief and satisfaction, everything (so far!) appears to be working after soldering it all up.



The first job was to test it on the bench to ensure that results were consistent with the last board.

Here's that same chart as before, where I measured the retardation on the horizontal ignition, whilst the ECU software was set to fire at a fixed point in the cycle (TDC). Although you can't really see it - I've added a third data series for the new (v3.7) board. That's a good thing though, because the updated board response is tracking pretty much exactly the previous (v3.6) board response, as expected.



Here's another view of the same data, but eliminating the lousy v3.3 data series, and zooming in on the retardation (Y) axis..



It's an interesting shape of chart, but the good news of course, is that the new board is behaving at least as well as the old one. I'm not clear if the two large increments in retardation is due to software or hardware latency, or even whether it's an artefact of the simulator rig that I created, or the ECU itself - but it's a fact that all ECUs will have to deal with this, and as long as it is consistent, then it can be dealt with.

So - bench test successful. Hooking it up to the bike, I notice that the fuel pump relay is clicking while it primes. I suspect I'm low on fuel, which might be putting stress on the controlling transistor. Either way, I'll find some time to further investigate.

The next step after that will be to investigate whether I need hardware noise filters (capacitors) on the crank signal on the bike itself, or whether it'll interpret the crank signal as smoothly as it did on the bench test.
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shay001



Joined: 23 Sep 2016
Posts: 80
Location: Trunkey Creek, NSW Australia

PostPosted: Wed Jan 05, 2022 11:43 pm    Post subject: DB2 ECU Reply with quote

Thanks for posting that info. I'm in a similar position with a recent purchase from Holland. It's a 1995 DB2 (SR?) with the same ECU. It won't run at all, in as much as the fuel pump does not run when the ignition is turned on. The relevant relay will not actuate when in situ, but works fine when isolated from the system, which makes me suspect (gulp) the ECU.
The bike arrived with a truckload (almost) of spares, including a spare barrel, spare pistons and a spare ECU with a spare eprom attached, but as the Walbro unit on my 3D Tesi is also playing up (no cold idle) I am seriously considering ripping both systems out and replacing them with the relevant Ducati systems (Magneti Marelli) which seems infinitely more reliable and of course no problems with software.

Any thoughts on this action appreciated
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hindsight



Joined: 13 Feb 2010
Posts: 126
Location: Central Scotland

PostPosted: Mon Jan 17, 2022 4:28 pm    Post subject: Re: DB2 ECU Reply with quote

shay001 wrote:
Thanks for posting that info. I'm in a similar position with a recent purchase from Holland. It's a 1995 DB2 (SR?) with the same ECU. It won't run at all, in as much as the fuel pump does not run when the ignition is turned on. The relevant relay will not actuate when in situ, but works fine when isolated from the system, which makes me suspect (gulp) the ECU.
The bike arrived with a truckload (almost) of spares, including a spare barrel, spare pistons and a spare ECU with a spare eprom attached, but as the Walbro unit on my 3D Tesi is also playing up (no cold idle) I am seriously considering ripping both systems out and replacing them with the relevant Ducati systems (Magneti Marelli) which seems infinitely more reliable and of course no problems with software.

Any thoughts on this action appreciated


Hi Shay -

Apologies for only just spotting your post.

If I'm reading this correctly, then you're saying that the fuel relay itself is working fine, but just not being activated by the ECU. If this is the case, then it's likely that the ECU microcontroller is not correctly starting.

Most often this is due to a problem with the chip (where the microcontroller program is stored). If you haven't already, pop open the ECU box, and make sure that the EPROM is correctly seated in the socket, if that doesn't work, double-check the other combinations that you have from the EPROM & ECU that you have.

I haven't done much on this project in recent months, but this might well be an option for you.

Take a close look at the picture of my ECU, and you'll see my email address. Drop me an email if you'd like to discuss further.

Regards,
Mike
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shay001



Joined: 23 Sep 2016
Posts: 80
Location: Trunkey Creek, NSW Australia

PostPosted: Thu Jan 20, 2022 1:08 pm    Post subject: the ECU and eprom are fine Reply with quote

It would appear that I might have dodged a bullet. The bike was "displayed" by the previous owner (their words, not mine) for an unspecified length of time that could have been a couple of decades WITHOUT draining the fuel. The pump, fuel lines, filter and quite possibly the injectors are choked with a brown tar like substance which is in fact residue from fuel.
Before I suspect anything the whole system will have to be cleaned and individual components cleaned, including the fuel tank.

I've seen cases of neglect, some not that bad, others worse, but this one takes the biscuit for plain old garden variety stupidity
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Bud977



Joined: 03 Mar 2013
Posts: 525
Location: Sydney

PostPosted: Thu Jan 20, 2022 8:22 pm    Post subject: Reply with quote

I know what that stuff is. I just recommissioned a '97 Suzuki RF900 which had 2km on the clock. The tank and carbs were coated with this sticky fuel residue.

At first I thought the tank was corroded, but a quick test revealed a nice zinc plated surface under the gunk.

It was nearly impossible to remove this gunk from the tank. Hardly anything solvents dissolve it. About the only thing that had any effect was acetone, but I didn't want to ruin the paint. I ended up pressure washing it the best I could with a detergent.

So you'll just have to get everything apart and scrape and clean. Not easy. Good luck with it.
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