Ignition problem, intermittent, iBeat logs of good and bad runs

Recently, my bike has developed a bad symptom. It starts and idles fine, but shortly after a very spirited high rpm, open throttle I notice a significant stumble, bog at just above idle until nearly 1/2 throttle. It's intermittent though...I've checked fuel pump, spark plug, valves, fuel and all connectors. I'm starting to think it may be a bad TPS or the coil going soft.

Searching for 'tps' is difficult, I'm looking for the specs to test (voltage or resistance) the TPS to ensure it's working normally.

Bike has 178 hours, 3000 miles, SoCal hard pack trail riding mostly.

Full history here: http://spreadsheets.google.com/ccc?key=rANyD42zKkOAQLbCEhacQ0A

Thanks for any test specs or other troubleshooting ideas.

The fact that its an intermitent problem makes me wonder.
Fuel supply issue? Fuel pump? Filter? Vacuum issue, or other fuel delivery issue?

Really so so many things come to mind, but all of them odd balls.

Good luck homie. Let us know what ya find.

Personally TPS wouldnt be on my top 10 list, but what do i know. I have disconnected TPS and found the bike runs fine that way, at least on the carbed bikes. Not sure with EFI.

How about just an over oiled air filter...

I've tried all the simple troubleshooting steps, air filter (I've over oil once before and knew right away), different gas, new spark plug, fuel pump seated. I think the efi is quite dependant on the tps, but I don't know for sure.

I'm going to call George and take the bike to him for expert diagnosis, plus I could use his magic efi tune.

It's been consistently inconsistent, I'll let you know what George finds.

Mike, thanks for the air filter idea. I changed it last night and got out for a spirited 90 mins. at the local proving grounds this morning (you know the place) and was unable to duplicate the problem. Motor simply ran great no matter what I tried to put it through.

I thought I had changed the filter since this problem started, but perhaps not. I don't change my filter all that often as I ride by myself 90% of the time, but have ridden with others the past couple rides recently, may have been just enough dirt to reduce the flow. More rides will confirm, dang it's hot and dry out there...

The symptom sure felt like the ignition was being retarded as opposed to starving for air, but if that's all it was I'll gladly take it!

I'll still hook up with Master Erl for a EFI tune, been meaning to have him do it for some time now. Just learned George is off this week so I have more time to ride and diagnose. Maybe Arrowhead later in the week.

Thanks

Update. Air filter was not the cause, I've experienced the problem several times since, though still not consistently...yesterday believe I've found the root cause. My throttle cables were catching the key and nudging it just enough to break contact of the switch. I rode a sequence of turns that catapult into the next and would often have the 'problem' through these, this time the ignition cut off completely, this is when I realized the cables had caught the key.

I've cleaned the contacts with freon*tf and cut off 1/4" of the plastic part of the key, the cables no longer can contact it and two rides have been symptom free!

Sometimes it's the simple things that can be hard to duplicate while not riding.

That is a fantastic repair - you could lose weeks chasing something like that down.

Good job! I'm going to check mine for clearance.

MAT

Well guys, my ignition problems continue. Some rides are OK, other rides the engine is missing every 3rd stroke, barely rideable. I've pulled my ignition coil and tested the resistance. The primary is OK at 4.8 ohms, but the secondary is bad at 21k ohms, it should be 5k ohms, plug wire/cap are good at 5k ohms. The resistance increases when I heat it and decreases when I cool it. No one within an hour or more has one in stock. Dan at Motoxotica ordered one for me. ~2 weeks out.

Are you going to have the PC on it when you bring it to Uptite?

I never did make it up to see George, spoke with him today regarding the coil though. You NEED a PC V + AutoTune for you bike! Really, it's that good! Even with my sporadic ignition problems, the PCV+AT have made the thing flat rip like never before...I've ridden a few inadvertant wheelies lately...so much more power everywhere and linear.

I've never noticed dimming, but as a troubling shooting step I took the ignition switch apart and was surprised at the corrosion build up on the contacts. If you heat the outer shell it's much easier to pop out the inards...very simple switch. Clean it up and coat it good with dielectric grease, then tape up the small hole that let in the junk (water).

Quick update. The 'ignition' problems continue. I've replaced the coil and the compete stator/pulse coil assembly, cleaned and dielectric every connector and switch (twice). The replacement coil measures identically to mine, looks like the book is wrong. Same with the stator, identical measurements between both and not in agreement with the book.

Ken (Joliet) loaned me iBeat, no error codes, ever recorded in the ECU. Of note, the ECU reports it's been run for 78 hours, though the bike has 205 hours. I"m going to ride with iBeat logging on my laptop in a backpack and try to capture the ignition 'event'.

Even George is stumped.

I'm open to any and all ideas. Could the auto decomp be engaging at higher than normal rpms and bleeding off enough compression to 'miss'? or how about carbon build up on the valve seats from running the stock AFR that is very very rich at 10:1 or 11:1 causing compression issues? or a weak valve spring(s)?

The problem happens between 2% and about 20% throttle positions, if I can nurse it through this range it will seemingly pull strong as ever. So it's either idle or flat out! And it still only occurs on some rides, about every other or every third time I kill the ignition and re-fire the bike. Still starts and idles easily and well. It does happen more often after the bike is good and fully warmed up.

I'm phoning George Sunday to attempt to review with his Holland contact!

Big thanks go Dan at Motoxotica for giving me such a great deal on the stator and coil from his personal bike. Dan, I'm afraid I'll be sending it back to you shortly they made zero difference.

Thanks for reading, I'm getting quite frustrated but keeping it in perspective too.

Brett

It sounds electrical rather than mechanical...

Have you tried disconnecting the kill switch? Security of HT lead into coil and into plug cap? If it was an EFI wiring or sensor issue severe enough to affect the running the Ibeat should record it so I'd be tempted to look at the related items.

Good luck!

Dave

I have cleaned the kill switch but not ridden the bike with it disconnected, I'll try that thanks. I've also checked the plug lead into the coil and cap. I've tested the cap, and it measures correct resistance ~5k ohms, though I may find a replacement today to rule out that when hot resistance goes up.

I agree it sounds electrical, hence all that I've done so far, I just don't want to ignore any potential mechanical causes...

While attempting to learn more, while riding I pushed the kill as lightly as I could...it would kill the ignition consistently, whereas the problem is not so consistent, I clearly don't lose spark every stroke as the kill switch causes. I've also been through the ignition key switch, cleaned and greased it.

I had a similar problem a few weeks ago where my by started run rough and missing, especially at lower rpm. It turned to be a bad battery. If the bike doesn't have a solid power source it runs like crap.

I'd would check all the main battery wire connections and may consider replacing the battery. Don't forget to check the connections on the starter relay and the battery ground cable at the engine.

If you data log while you ride be sure to log the battery voltage.

Thanks Seymore, I've bypassed the kill switch, problem still occurs. I was successful at logging both a good run and a bad run.

The difference I see in the bad is the injector pulse goes to zero whereas the good run it does not.

So, bad injector or bad signal to the injector? If bad signal I would expect the ECU to record an error.

I've yet to pull the injector to inspect it but will do so shortly. Anyone had to a replace one yet? Is it a common Bosch injector?

Thanks for the suggestions, keep them coming. I've attached the good and bad run logs if you have iBeat and want to have a look. Let me know if you see anything else besides the injector pulse going to zero.

My voltage reads fine throughout both logs. The injector pulse width of zero appears to be the problem, or the result of something else gone wrong, like the ECU not sending the signal to the relay to the injector. I've checked the three relays, all within spec, and swapped them around so the injector has a different one driving it now, no change. I cleaned the connectors again, no change. When I say clean I mean deoxidizer and conductivity enhancer for electronics. Along with dielectric grease for the non-oring sealed connectors.

I just rode for over an hour without issue, stopping the engine 4 times during the ride. Just a few minutes from home I repeated shutting off the engine and firing it back up, problem returned and remained throughout three more off/on. It's definitely throttle position sensitive (not necessarily TPS though, the logs show appropriate TP and ignition advance throughout the zero injector pulse events) as the problem only occurs between 2% and ~20% throttle, this part has been consistent.

I attempted to remove the injector but was unable to remove the two Phillips head screws that retain the bracket, damn they are torqued and was afraid I'd strip the heads.

Coffee, I do have PC V w/AT, but had this problem prior. PC V with or without AT does not seem to affect it. Though I believe it screws with AT because it sniffs an inconsistent AFR as the injector goes on and off. I've disabled both PC V and AT and eliminated them from the FI system for now.

It's unfortunate that the workshop manual is most likely wrong on the coil resistance leading me down that path to replace it without cause.

The 2 HT coils I have (one from known working bike) read 20k and 21k ohms (book says 5k ohms). Would someone please measure theirs and report the reading? Measure resistance between either of the crimp-type tabs (primary) and without the spark plug cap/cable attached, or with the cap/cable attached it should add 5k ohms to the total.

Even if the coil is on the edge of working, I don't see how this would cause the injector to not pulse, or the ECU to report zero pulse.

Still bummed.