cold start update
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Good luck mate!
Ditch said he was going to try. I gave him some pointers but didn't hear back so I assumed the worst and it didn't work for him, I dunno though. It worked for me. I've had zero cold start issues since I wired up the diode shunt. My bike fires instantly and stays running when I release starter button. I can also release starter button the moment my bike fires. Before the diode fix I would have to hold button down for up to 10 secs and give the bike some throttle. Now I can just stab the start button.
I believe Rob is right, at least in regards to my bike. When the starter button is released a negative voltage spike is generated. This voltage spike is fucking with the power commander somehow and causing a malfunction.
I emailed dynajet a dozen times in regards to the cold start issue. Each time they replied with "its a power supply problem" and the unit would test out fine. Then I emailed them about the diode fix and suggested that the pc111usb was susceptible to negative voltage spikes at start up. I never got a reply, the only time no one replied? Kinda is a power supply problem. Perhaps some bikes just generate a greater negative voltage spike at startup? Which would explain why some bike have it and some don't.
It a very easy test. Just follow Rob's excellent instructions. I got a bag full of diodes for a few dollars from ebay. They come with 1 inch wires on either end. For the test you only need to extend the earth end. It's best if the diode is connected as close as possible to the start rely (source of negative voltage spike). So just push the diode wire into back of starter wire spade terminal. The other end (earth) I ran a 6 inch wire to the mounting bolt for the coolant overflow tank. Clean off paint and rust at earth point. Cross fingers, pray and hit starter button. I've made the diode connections more permanent now, solder, heat shrink etc. Can post a pic of my setup if ya want.
I sort of figured with winter approaching the cold start issue would rear it ugly head. Would be really awesome if someone else could replicate what I found. Cause at the moment I think I'm the only one that has fixed their cold start issue, at least with a diode shunt.
Of all the problems my bike has had the cold start issue has been the most frustrating. I love my pc111usb. I'm on my third set of pipes now and I know I'll try others. Every new set of pipes needs a tweek to the fueling and the power commander is a good tool for this. It's also allowed me to smooth out the bike in the lower rev range. I would hate to remove it permanently.
Thanks wrist twisters for helping me out.
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Derpydog did you have any luck?
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First pic is my test lead. Second pic shows the diode wire soldered into starter relay red/yellow wire terminal. Third pic shows permanent wiring. Diode wire is the black/white wire running from starter relay plug. There is about 3 inchs of wire then a diode. Which is soldered and heat shrunk. Probably best to keep diode as close as possible to source of negative voltage spike which is the starter relay. There is a foot or so of wire running to earth, under frame to the coolant bottle mount point.
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213 Posts
I will be doing this tonight. I think some of the reason why select people have this issue, and some do not, is because all bikes with the PCIII have the issue- but not everyone rides their bike early in the morning or has to start it in cold weather. If its warm outside on initial start up- I hit the button and go... If its below 40*f, I have to play the "starter button tap dance" till she fires up.
I bought the diode last night, and will be doing this tonight. I will report back ASAP! I hope to be able replicated the results and fix this issue for good!
Thanks Guys!!!!!
I bought the diode last night, and will be doing this tonight. I will report back ASAP! I hope to be able replicated the results and fix this issue for good!
Thanks Guys!!!!!
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Don't you want a beefier diode than that?
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The size diode Rob suggested is enough. It's only a voltage spike, very brief, that is negative and running in the opposite direction to the normal current path. There is no real power current running through the diode. The diode just provides a pathway for any transient negative voltage spikes to run to ground, before they mess up the power commander. Also I've been running the diode shunt circuit on my bike for several months now, no cold start issue and no problems. If you are curious do a Google search on flyback voltage protection and flyback diodes. Negative voltage spikes are very common in electrical circuits. There are any number of diode shunt protection systems used to protect stuff.
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To paraphrase Mr. Tharlson:
REMEMBER ! The Cathode (banded) end of the diode, not the unbanded Anode end, is what has to connected to the positive line of the coil !
Diodes allow electrical flow in one direction only, and that direction is Anode to Cathode.
REMEMBER ! The Cathode (banded) end of the diode, not the unbanded Anode end, is what has to connected to the positive line of the coil !
Diodes allow electrical flow in one direction only, and that direction is Anode to Cathode.
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I assume the diode would fry so fast that nothing would get hurt.
Proof positive that bigger is not always better, diode rating versus application that is ......
ALSO
I created a new folder in the Dropbox specific to the cold start issue.
I pieced together a document of the salient points, pictures and diagrams.
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Quick update. Cleaned up my original harness. Shorter harness, shorter is better in this situation. Got diode closer to starter relay. Also got shunt wire to run through the rubber boot on starter relay. Earth wire is shorter and moved. I took a couple of pics. First shows diode soldered up before heatshrink. Second pic finished shunt harness.
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Dropbox document just updated accordingly, by text and pictures.
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Hell yes. Well done mate, that is an awesome result. That's two positive results. That's good enough for me. The diode shunt works. I must admit I was worried it was a one off.
Bet you were like "I'll be f****d" when you first tried it. If you get a chance disconnect the earth end and try starting the bike. My bike starts without cold start issue even with diode disconnected? Weird. Maybe it would come back over time. Which is how it started. Got worse over time.
How good is with no cold start?
Rob PM me your address and I'll post you a little bottle of Aussie rum. Yeah.
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First time with the shunt she fired up- it was 34 degrees out. I was shouted in my driveway like a buffoon at 4:30 in the morning "hell yeah!". Mine started slowly over time as well but only after the PCIII was installed. Im betting dollars to donuts that if you leave the shunt disconnected, or replace the battery, that it will start to come back. I also went ahead and reloaded my map after 3 days to see if it would restart the issue. To my surprise- nothing happened- just started first try with a 2 second button press. I have not had an issue at all since. Before the shunt I would have to hit the go button 3-5 times before she would stay running. Now i'm happy my honda starts like a honda should- every time!
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When I first installed pc111usb I had no cold start issue. It developed over several months slowly getting worse. Ended up either 3-5 start attempts or 15 sec button hold and some throttle. The diode shunt worked immediately. Zero cold start issue now regardless of startup temp.
I've since swapped out battery and also swapped out pc111usb maps several times. All good still.
I still worry everytime I let that start button go. That cold start issue traumatized me. So good now, starting like a Honda should.
I've since swapped out battery and also swapped out pc111usb maps several times. All good still.
I still worry everytime I let that start button go. That cold start issue traumatized me. So good now, starting like a Honda should.
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103 Posts
Hello!
First big thanks to robtharalson for the analysis and suggested solution, to Islandboy and Nealio919 for testing and sharing the results and drivit for opening this discussion.
I just installed the diode on my bike too. Because electronics components are brittle and susceptible to shock and the leads are kind of weak, I decided to install mine in a little piece of PCB, soldered to it and the wiring was soldered on the bottom of PCB. Then, coated all the assembly with some conformal coating and cover it using two layers of heat shrink tubing, then installed on my bike. I will be testing it next Tuesday (leaving my bike outside for the night) and I will share the results.
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Thanks!
First big thanks to robtharalson for the analysis and suggested solution, to Islandboy and Nealio919 for testing and sharing the results and drivit for opening this discussion.
I just installed the diode on my bike too. Because electronics components are brittle and susceptible to shock and the leads are kind of weak, I decided to install mine in a little piece of PCB, soldered to it and the wiring was soldered on the bottom of PCB. Then, coated all the assembly with some conformal coating and cover it using two layers of heat shrink tubing, then installed on my bike. I will be testing it next Tuesday (leaving my bike outside for the night) and I will share the results.
Thanks!
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