I think I'm about to give up and turn it into yard art....
New GYZ Yuasa, Great battery - thanks, Mr. H. Top quality battery.
Cranks better than it ever did.
All fuel system checks = good.
No faults = good.
New plugs = good
New plug wires = good.
New NOS coil = good. Old coil Ohms out fine too.
Starts and seems fine. Run it for a few minutes and shut down. Start it again, might be fine, might not. Shut down, let it sit a little bit, try it again, sounds like only one cylinder is firing and stumbles. Rev it to clear it out, and it is much better, but a definite misfire. No codes. POS ! What the hell. It chuffs in the intake and a misfire in the exhaust. It obviously has something that is failing and is not apparent when first fired up. WHAT ??????
Something is heat-soaking and going open or failing! WTH !!!! No codes - so it can't be a true misfire right? The fuel system is fine - SO WHAT THE HELL !
It has to be an electrical controller or temp sensor or coil or WTH....
Me and this bike are not mating well. I was told, everyone should try an HD once. Well I did, and as much as it's a kick in ***, I about fed up. I do not know what else to check or replace.

IAC, IAT, Crank Pos Sensor - what the hell is wrong with you bike ?????

 

I know how frustrating it can be trying to diagnose an electrical issue....



"IAC, IAT, Crank Pos Sensor - what the hell is wrong with you bike ?????"

Of the parts mentioned in the above question, the crank position sensor directly affects when the ECU sends a spark to a plug. A failing CKP can cause misfires. Electrical components, when starting to fail, can act intermittently, and more so as the component gets hotter... I have also read several reports of a intermittent failing CKP that didn't throw codes. Once the CKP completely fails, the bike won't start.

At this point, after all you've done, I'd focus on the CKP, crank position sensor. It is #32707-01C and lists for $71.53 from a dealer.

You may want to find the CKP plug in the harness, and check for a good clean connection, and or crimped/pinched wires in that circuit that could cause intermittent issues, before spending the $72. If you have the electrical diagnostic manual, it would tell you how to check the CKP. You could test the pins coming out of the harness to the CKP for proper signal. You want to make sure the problem isn't between the ECU and the CKP connector.

It would even be more frustrating to spend the $$ on a new CKP, only to find the issue is the ECU, ECU pins, or wiring from the ECU to the CKP.

That's all I got from what you now describe.

Good luck with the CKP diagnostics.. Keep us posted.....

 

Thank you Mr. H !
Yes, at this point, I am leaning towards the CPK also. Actually, it was one of my first thoughts of what was failing while trying to get home. It was the first thing that I did a visual inspection on and removed it to make sure the pick-up was clean, which it was. I did not look in my Electrical Troubleshooting manual for the procedure on how to electrically check it - but I will.
I got sidetracked on the wires, plugs, and battery.
Triumph, which I also have, is notorious for CPS's going bad, and that is why it was my first thought. Back to square one and check it out.

Thanks for taking to time to respond and help me keep going in the right direction Mr H !

Added - I did check the ECM and its wiring and connectors. Everything looks spotless.

 

That's good, you can find what signals it sends to the CKP from the Electrical Diagnostic manual. Then measure them at the CKP connector while trying to start the bike. It should rule out any wire/connector issues other than on the CKP itself. With good signals, the CKP MAY test good, since it's an intermittent problem, so your call at replacement at that point.....


On your one post about this, Max was giving you some advice. He is much more experienced and smarter than I.. SO I just gave that thread a quick glance now and then.

in your next thread, I too got side tacked by your discussion of the codes, all you did, etc, etc. I too originally thought of the CKP, but misread your "inspection" of the CKP as "tested"....

When I saw you mention it above, the light bulb went off in my head, I re-read and saw you "inspected" it, not "tested" it.... Sorry I missed it as a good potential for your issue originally...

 

Ooops, just checked my last message....

The ECU probably doesn't send anything to the CKP. It probably just receives a signal from the CKP. You could check the CKP for a proper signal at that connector, then check for continuity (no shorts) between that connector and the correct pins on the ECU connector.

Forgit to proof read it before hitting send...

 

You could also borrow/swap from a good specimen if you have one available. You would never imagine how many issues are diagnosed this way all the way back to the old 60’s hot rods I have worked on.

 

After reading my electrical troubleshooting book, it looks like an HD scanilizer unit is needed to check the CPK, as they describe. But I did check all the wiring and cleaned the connectors even though they looked fine.
Here is the latest. Cold, fires up and sounds like it is running fine. Run for 3-4 minutes at different rpms. Shut down, let sit 10ish minutes. Start, sounds like only one cylinder is firing until I give it throttle, and it clears up but has a chuff / puff in the intake and sounds like a misfire in the exhaust.

It is definitely some kind of heat breakdown from soak-back. I believe it is time to buy a CPK.

I wish there was someone to trade parts with but there isn't. I don't like throwing parts at it, but I don't think there is much other option at this point other than just making the best "guess" and trying something. $71 for a CPK sensor is not too bad, especially if it fixes it.

 

There's a couple troubleshooting videos on YouTube that describe problems very similar to the one your having. I'm not one that likes to play the parts cannon route but in this case what's 70 bucks. If that doesn't fix it then try a different approach.

 

I absolutely agree, and I am not a throw parts at something guy either. I always troubleshoot, and I want to find the item and fix it. But, this time I have about run out of things, and even if I buy a couple of parts, and they don't fix the problem, spare parts for my 23-year-old bike are probably a bad thing to have. I just want ot get it going again. I really like the bike, but it's wearing me down.
I did not find much on utube, but I'll look again. Not much of a utube guy usually. But thank you.

 

Seems to be a common failure on the twin cam 88 motors. There's a few threads on here describing similar issues like yours. This vid on the Tube describes how to test but the bike he's working on is a Dyna and the deutch connector might be in a different spot. He also describes how it works. Worth a look