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DB2SR - winter project turns into lockdown project
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TVRRICH



Joined: 05 Feb 2016
Posts: 211
Location: Coventry UK

PostPosted: Wed Jun 03, 2020 11:39 am    Post subject: Reply with quote

Oh also, as i said before i didn't fit the carbs so i don't know who set up the cables/linkages etc. Seems to work alright though
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hindsight



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

PostPosted: Sat Jun 13, 2020 4:01 pm    Post subject: Reply with quote

I'm probably overdue an update here, though truth told, I've not done much with this in the last few weeks, some work pressures have dominated my time unfortunately. No matter though, I've now booked a week off work and I've got a couple of interesting things to share..

Last time, the new injectors were working, but I was getting a lot of misfire at both ends (intake and exhaust) - and it was LOUD.. To progress that, I first wanted to go back and check the timing: the angular distance between the flywheel pickup and TDC - last time I did this, I removed the engine cover to mark up TDC on the flywheel so that I could see it through the window (it's not aligned to the flywheel marks!).

On the DB2, frustratingly it seems necessary to drop the engine slightly to get one of the engine cover bolts out, so I was keen to not have to do that again. I figured I could install a timing wheel on the crank turning tool, and indeed, the crank turning tool is designed to allow exactly that - however - I didn't like the idea of the metal turning tool with handles spinning fast. Seems more dangerous than it really needs to be.

I took the opportunity of my recently purchased 3D-printer to design a degree wheel holder - compact and light, but yet strong enough to be bolted securely onto the end of the crankshaft and not to allow the degree wheel to slip. Coupled with a pointer that bolted into one of the clutch slave mounting holes, it did a good job, and I noted that my previous measurements (and therefore calculations) were off slightly, allowing me to correct and improve that.





It's now idling reasonably well on the ST2 map, though I had to further reduce the fuel to eliminate the popping. Over the next few days I'll continue to tune the fuel map to ensure it is starting and running as best as I can get it over as much of the rev range as I can - and once I've eliminated as much misfiring as I can, I'll reconnect the O2 sensor and see where that takes me.

Slightly annoying, it seems that DHL have lost my PCB package en-route from China, so I've just had to instruct them to make a new set of boards, so it'll be another few weeks before the new PCB gets here.
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brian



Joined: 22 Aug 2011
Posts: 3769
Location: Australia

PostPosted: Sat Jun 13, 2020 9:57 pm    Post subject: Reply with quote

Nice job on the 3D printed tool Cool
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'99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851
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glened



Joined: 15 Aug 2013
Posts: 135
Location: Lancashire

PostPosted: Sun Jun 14, 2020 8:11 pm    Post subject: Reply with quote

Hi Mike, like Brian I am suitably impressed with your 3D printing expertise. I have just acquired a lathe, pillar drill, milling machine etc, now it looks like I shouldn't have bothered and just got myself a 3D printer Smile looking forwards to more instalments. Regards Glen
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aarthodo@gmail.com



Joined: 16 Jun 2020
Posts: 2
Location: NL

PostPosted: Tue Jun 16, 2020 12:23 pm    Post subject: Reply with quote

Hello hindsight and other contributors
I ve been reading this interesting item, because i own also a db2 sr 1995 building year, with the original injection system, and 46000 km on the odo. I own it since 2000.
In the netherlands a firm in Helmond: carmo has once repaired my ecu, after i blew the ignition transistors.
After that it ran even better.
The engine was running rich and made the original spark plugs brown/ black.
Since i changed to iridium this is no problem anymore.
Also after the winterstop i use injector cleaner fluid wynns or forte in the 98 ron fuel. This makes it running even less rich, because the spray pattern from the injectors improve.
Obvious gains from your project are better mapping, cleaner sparkplugs, and more top end power, because the original injectors spray continuously above 6000 rpm.
My next maintenance item is renewing valve stem seals or what will be found more in that area😅
Anyhow happy tuning and tweaking!
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hindsight



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

PostPosted: Wed Jun 17, 2020 8:22 am    Post subject: Reply with quote

glened wrote:
I have just acquired a lathe, pillar drill, milling machine etc,

Hi Glen,

For several years I've toyed with doing similar, but came to the conclusion that (for me) the infrequency of use, and the large amount of space required for these things were not a good trade off. The 3D printer is relatively compact, but I'd imagine that the materials it can extruded (PLA, ABS) are different to what you'll be using in your gear - and each set of equipment will be useful for its' own purposes. What I have found is that each design at the moment usually requires two or three attempts to get it just right - so it's definitely not a quick process, but then I'm still learning the tricks of design.

aarthodo wrote:
Hello hindsight and other contributors
I ve been reading this interesting item, because i own also a db2 sr 1995 building year, with the original injection system, and 46000 km on the odo.


Interesting!, thanks for contributing to the conversation Aarthodo - I'm aware of carmo only from them popping up in Google searches while researching. Out of interest - do you know what caused your ignition transistors to blow?

I also had the valve stem seals replaced as a matter of course when the heads were reshimmed to match the ST2 cams.

I had a brainwave yesterday, and I'm currently working on a method of programmatically simulating the engine running (at variable RPM and Throttle) and measuring the duration and timing of the ECU outputs whilst disconnected from the bike. It's partially an academic exercise I suppose, as I probably don't need to do this, but it's interesting, and I might learn something along the way that comes in useful. I think it'll also be a useful test harness to allow the ECU configuration to be tested off-bike to check the upper ranges of throttle position and RPM against injector duty cycle.


Mike
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aarthodo@gmail.com



Joined: 16 Jun 2020
Posts: 2
Location: NL

PostPosted: Mon Jun 22, 2020 8:53 am    Post subject: Reply with quote

I'm not keen on telling about blowing the transistors😅 ha ha.i wanted to check and let the bike run on 1 cyl, with one sparkplug outside the engine.not touching the block.it could not stand that old fashioned test......
Something else, do you know about the existence of a programmer for the tdd walbro ecus? I have a small user manual of that i think, but there are no mapping data in that.
Success with your interesting project!
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hindsight



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

PostPosted: Mon Jun 22, 2020 1:37 pm    Post subject: Reply with quote

aarthodo@gmail.com wrote:
I'm not keen on telling about blowing the transistors😅 ha ha.i wanted to check and let the bike run on 1 cyl, with one sparkplug outside the engine.not touching the block.it could not stand that old fashioned test......

Wow - I'm really surprised at that. I've done that a LOT recently (though, mainly on the new ECU when I was still testing).

aarthodo@gmail.com wrote:
Something else, do you know about the existence of a programmer for the tdd walbro ecus?

I gave up looking for the right software to make fuel maps, which is ultimately why I went down the route of creating a new ECU.

aarthodo@gmail.com wrote:
I have a small user manual of that i think, but there are no mapping data in that.


I'd be interested to see a copy - is it something you can share?

I'm in the middle of some useful progress on the electronics side of this project, and should be ready to write up some interesting notes later this week hopefully.

Mike
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hindsight



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

PostPosted: Sun Jun 28, 2020 4:27 pm    Post subject: Reply with quote

The last couple of weeks have been interesting and frustrating in equal measures. I'll warn you now - this is a pretty long and geeky post, apologies. Very Happy

Last week I had a bit of a brainwave.. I figured that by hooking the ECU up to a microcontroller, I could simulate an engine (by providing the signalling to make the ECU think it could see a crank sensor and TPS). This seemed like a good way of providing an additional test harness that would allow me to programmatically test the full rev range at all throttle openings - partly an academic exercise I guess, but it was interesting none-the-less.

It then dawned on me that if I could also sense the output signals of the ECU, then I could measure it's accuracy (pulse duration for injectors, and timing for ignition). A plan was hatched. It took a few days, and it wasn't pretty, but it worked.



One of the interesting things about this is that although I designed this really to test the new ECU, I could also adapt it for the OEM one, and measure its output.

As an example, here's the ignition curve, from the OEM ECU measuring the angle before Top Dead Centre (BTDC) of the horizontal ignition across the whole rev range, at 50% TPS.



Interesting to note the timing retard and flatten at >8000rpm. That looks like a soft limiter, and I'll set the new ECU similarly.

I'll skip the detail of how this actually works, but at each of the TPS/RPM combinations of interest I took 200 measurements, eliminated any obvious outliers that might have been instrumentation errors, then averaged the results. That chart was constructed by interrogating each and every RPM between 1000rpm and 8500rpm to show a smooth curve.

I used a similar technique to reverse engineer the whole ignition map from the OEM ECU and obtain the data that I could import into the new ECU. That was pretty satisfying, but over engineered and a relatively minor improvement over what I could have got from using a stock map from another Ducati engine.. Smile



Back onto the bike though - I've been chasing a couple of problems.. firstly, it had recently been idling way too high when fully warmed up (3500rpm or thereabouts). I had hoped that the new ignition table might help with this, because I could have sworn that the OEM ecu didn't have a high idle. However - after an amount of headscratching, I figured out that I made an obvious rookie error - I had been adjusting the throttle stop a few weeks previously, and I must have adjusted the balance screw, meaning that one cylinder was pulling way more air than the other, and there was too much air getting in overall. Dammit!, so out with the vacuum gauge, confirmed the issue and rebalanced the throttle bodies set the throttle stop and recalibrated the TPS. Once done, and I also adjusted the fuel map according to the O2 sensor, I got a beautifully stable 1150-1250rpm idle. Lovely.

The second issue was worse though, and more than once in recent days I've come close to giving up on this whole exercise. Since starting to try and tune the fuelling, occasionally, the bike would misfire (usually loudly in the throttle body) and stall. The ECU seemed to suggest that it was losing sync with the crankshaft sensor (which is a pretty terminal situation for timing accuracy..). I hooked the oscilloscope up, to have a look at the signalling from the crankshaft sensor and into the ECU - which was mostly clean, but some small isolated pockets of electrical noise (which could have been caused by the scope itself).



In the scope image, the blue line is the output of the crank sensor (remember the picture of the flywheel from the very first post in this thread? - the holes drilled into the flywheel generates that sine wave), and the yellow line is the square-wave input that the ECU uses - you can see small pockets of noise on each.

In any case, I figured that I could adjust the wiring to further separate the HT leads from the crank signal wire, and also revert the ECU to bluetooth comms (as I was using a USB cable, which *could* have been the source of interference). Things seemed to be a little better, but it was still stalling out.

I wasn't sure if the sync loss was cause or effect - it was initially my assumption that it was the cause. Now - one of the things that really appeals to my inner nerd here is the amount of data available. I started studying the performance logs in detail.. Here's an example of just some of the relevant metrics here:

Yellow=Air Fuel Ratio (from O2 sensor)
White=RPM
Green=TPS
Red=Sync loss counter (increments each time that a sync loss happens)



You can clearly see the TPS (in green) rising to 33% when I blipped the throttle, and shortly after, the RPM signal (in white) drops off after the misfire and the engine stalls, but what was particularly interesting was the sequence of events. The sync loss (red line rising) was detected after the RPM dropped off - in fact, it was about 250 milliseconds after, which (at the initial 1500rpm) represents about six rotations of the crank (not accounting for the deceleration of the crank, so probably less than six).. It's starting sound very much like the sync loss was probably a consequence of the event, and most probably the crank coming to a halt (which would surprise the ECU when it stopped receiving positioning signals).

What then caught my eye was the AFR (Air Fuel Ratio), which goes incredibly lean… and bearing in mind that there is always a small delay to the AFR reading arriving at the ECU from an event happening - could it have been the cause of the misfire and ultimately the stall?

It's interesting starting to understand the mechanics behind fuelling, and by adjusting both the idle parts of the map and the acceleration enrichment (which acts like an old skool throttle pump on a carb), I think I've been able to tune out these irritating stalls, leaving what feels like a motor that idles cleanly pretty close to the ideal AFR, with a throttle response that (on the bench at least) feels clean and crisp (so far - much more testing will be required).

Mike
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glened



Joined: 15 Aug 2013
Posts: 135
Location: Lancashire

PostPosted: Sun Jun 28, 2020 6:35 pm    Post subject: Reply with quote

Well done Mike,

What do you do in your spare time? help out at NASA? I think they had a problem with Apollo 13 Smile Seriously though please carry on with all the geeky stuff. I will bring baby bim up for a ride and you can explain it all to me in words of one syllable over a pint, just so that some of it might sink in. Regards Glen
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hindsight



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

PostPosted: Sun Jun 28, 2020 7:05 pm    Post subject: Reply with quote

glened wrote:
What do you do in your spare time? help out at NASA? I think they had a problem with Apollo 13 Smile


This is taking up a worrying amount of any spare time. Lockdown is starting to ease up here in Scotland, so hoping to still maintain a level of momentum on this, but also get out and do some fun stuff also.

Funny you should mention Apollo 13.. I've just finished listening to this podcast series.

https://www.bbc.co.uk/programmes/w13xttx2/episodes/downloads

Very, very recommended..

I'll look forward to meeting baby bim and yourself Smile
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hindsight



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

PostPosted: Thu Aug 13, 2020 9:34 pm    Post subject: Reply with quote

A little update.. I've not done terribly much on this for the last few weeks, partly because I had designed a new board, and was waiting for it to be fabricated in China and sent.

It arrived last week, and I got around to building it up yesterday.. to my delight it passed the initial bench testing, and I went on to pop it onto the bike this evening, which started and ran.

The key thing about this new board is that it makes use of a generic microcontroller, rather than a specialist EFI controller. That moves some of the complicated stuff to my PCB, but makes it easier to fix if there is a microcontroller failure. Additionally - it would make the design easy to adjust to other bikes/ECU types, which might be a direction for the future.



If all goes well, hoping to get the first roadtest in the next few weeks..
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glened



Joined: 15 Aug 2013
Posts: 135
Location: Lancashire

PostPosted: Thu Aug 13, 2020 11:22 pm    Post subject: Reply with quote

Hi Mike,
Nice to hear from you, pleased that the new board ran ok when fitted. Looking forward to hearing about the test run, hope the bike runs OK. Took baby Bim out for its first ride out after the accident. It ran like the proverbial bag of s**t, but what a hoot to ride. I have a 1963 AJS which if I decide to go for leisurely ride it is fantastic, but for sheer excitement give me the Bim. Catch up with you soon, I am hoping to take it up to Scotland in mid September.
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hindsight



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

PostPosted: Fri Aug 14, 2020 7:36 am    Post subject: Reply with quote

glened wrote:
Hi Mike,
Nice to hear from you, pleased that the new board ran ok when fitted. Looking forward to hearing about the test run, hope the bike runs OK. Took baby Bim out for its first ride out after the accident. It ran like the proverbial bag of s**t, but what a hoot to ride. I have a 1963 AJS which if I decide to go for leisurely ride it is fantastic, but for sheer excitement give me the Bim. Catch up with you soon, I am hoping to take it up to Scotland in mid September.


Nice! - I've got a '66 Ducati 250, but I find it an absolute nuisance to ride, so it tends just to sit in the garage looking pretty instead. Very Happy
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welshlamb



Joined: 09 Mar 2011
Posts: 592
Location: South Wales , Nr. Abergavenny

PostPosted: Mon Oct 12, 2020 11:02 pm    Post subject: Mind boggling magic electrical stuff Reply with quote

Time for an update??
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