Help with a wierd (electrical?) problem ...

[Lando]

Hi all, I've been having the most frustrating problem that i cannot pinpoint to a single cause. Maybe someone can help me figure this out without me having to replace every sensor on the bike. This has been going on since my last ride at the end of the season last year and every ride this season.

BTW, i have an 08 lightning with about 19K miles, K&N and Jardine. It has been running fine for the past 2 years with the mods, so that's not the problem. I'm sure it's running lean with that combo of mods but i don't think that's the issue.

The problem: the bike cuts off (feels like it ran out of gas) after 4K rpm most of the time either while riding or even in neutral. It runs fine if it's being babied.

Today i went for a ride and paid close attention, while riding slow, shifting early it runs perfect. if you shift below 4K, sometimes up to 4500 rpm all is good.
Once you keep revving past that, it falls on its face until the bike slows down enough for the engine to be below about 3500 rpm and then its fine again.
I also noticed that when it bogs, my tachometer dies down to zero, then jumps around a bit while the engine is trying to come back to life, and finally stabilizes again when it gets to around the 3K rpm range.

To me, this seems like an electrical problem and not mechanical as the bike is fine if babied.
There are no CEL lights, bike starts fine and runs strong otherwise.
Sometimes it even goes through the whole rev range without the problem showing up, lots of power as normal.

Another thing i noticed is that it also has issues sometimes on zero throttle decell after a hard pull up to 4 or 5K rpm, and whenever it does have its "issues" there are lots of loud backfires.

Things that could be a problem as far as i know are: Stator, head temp sensor, throttle position sensor, cam angle sensor, crank position sensor, coil, fuel pump, battery/grounds, chafed wires somewhere, voltage regulator, O2 sensor...

I have recently replaced the battery and the voltage regulator so I'm ruling those out as options.
I also took off the whole air box today and looked around and could not find anything wrong anywhere, no chafed wires immediately apparent, no melted connecters, no loose grounds, battery terminals are tight.
I also looked under the seat, couldn't see anything wrong, and didn't see anything wrong behind the fly-screen either.

Any opinions on where to look, what to test and how to test it? Suggestions?
I have the service manual, tools, and am mechanically inclined but this one is throwing me a curve ball.

Thanks for any help guys.

Lando

[confused]

 

[Lando]

What sensor tells the ECU/tach the rpm's? I'm thinking that is my problem.

 

[anrkizm95]

crank sensor

 

[Kohmeo]

I had the same issues on my 07 TT.

It would get it to 3500 rpm and then would sputter and die until it slowed back down to 3000. I could gun the throttle and get past that spot and it would run fine from 4000 to the red line.

It ended up being the engine temp sensor wire was rubbing and was grounding itself on the frame. Tapped it up and runs like a champ again. Temp sensor might be a place to start... But mines is an 07 and I have noticed that the 08's are a different kind of beast.

 

[SlyFox]

I had an issue with my Uly in 2010, which was an ECU remedy. But mine didn't have certain RPM limitations as to when it "turned off" and a second later back on...with no apparent rhyme or reason.

 

[Lando]

Thanks for the suggestions. So far, I'm leaning towards it being the crank sensor as it happens at certain rpm's only and the tach also dies while it happens and that sensor sends the signal to the ecu.

Yesterday I checked the wire on the head temp sensor as well as i could through the frame/airbox opening and it seemed fine, it has a protective sleeve covering it so there's not much accessibility to it.

The one thing that still has me doubting it is that the crank sensor is a hall effect sensor and it should either work or not work, and not have a range of malfunction like this... but we shall see $75 from now!

 

[captain13ron]

I woud try to hook up ECMSPY and do some recording. you can watch the Hall effect sensor as well as many other items. such as your temp sensor. if you do not have the software and the cable, pesonally I would not consider it to be a waste of money.

 

[Lando]

Does ecmspy work on Macs?

 

[iman501]

If it does work on macs I know what i'll be doing this month!

besides fixing the oil leak on my other bike.... :/

 

[Lando]

So, does anybody know? Before I go buying a cable.....

 

[Lando]

Ok, bad news, i wasn't the crank position sensor. That will be up for sale soon.

Now the problem is even worst than before.

I installed the new crank position sensor and started her up. All fine as usual. went for a ride and once she warmed up i started having the same issues, except this time even more severe to the point the bike just died and would not start up properly again.

No check engine light.

It was running really rough and choking throughout the whole rev range. wouldn't start up, wouldn't idle, seemed like it was running on one cylinder some times, lots of backfire and coughing, seemed to not be getting spark sometimes.

Any ideas????

My next guess is the head temp sensor... anybody got a part number?

BTW, does ECMSPY run on MAC/APPLE?

Thanks
Lando

 

[buellbradski]

Could it be a fuel line issue or fuel pump? Air getting in the fuel line ?

 

[Lando]

Maybe, but why would the bike run fine when cold?
The fuel pump ( chafed wires) is on my list of possible causes but way down the list.

 

[snrusnak]

Possibly the fuel pump. I've had many issues with cars where the fuel pump will randomly cut out especially once warm.

 

[thrstrmech]

start with reading the codes first... jump pins 1 & 2 in the dongle on the right side of the ecm, you can do it without ecmspy. easier than guessing and throwing parts at her which may or may not solve the problem. reading the codes gives you a better idea of where to start from, could be one faulty part or two causing the issues. after reading the codes, follow the troubleshooting flow chart in the manual. don't have the manual: use the link below the buellxb header or from buellmods.com, good luck and post your findings...

 

[07Bolt]

Have checked the battery cable connections? Are they tight? 08s don't usually have a lot of problems. Why did u replace the volt reg? Fuel pump wires could be rubbing together also. Almost sounds like intake leak. With enough air at 4500 rpm it could be causing leakage. Check ur plugs to. When u baby it, its only reacting to normal riding situations.

 

[Lando]

Ok, so i finally had some time and went to check if there were any codes.

No active codes, but there were 2 codes in memory - code 11 (Throttle Position Sensor) and code 44 (Bank Angle Sensor)

I printed out the troubleshooting guides for both of these codes from the 05 manual here, but i have an 08 so the TPS is different and i don't know how to diagnose it, as my service manual does not have a troubleshooting section.

Does anyone know the part numbers for the TPS and for the BAS on an 08?

Reading though the 05 manual, it seems i might have a chafed wire somewhere as there are shared wires for both sensors.

Thanks for any help solving this...
Lando

 

[christianmb]

Lando, this is the same problem I have been chasing for a year and a half on my '07. I did what you are doing, replaced every $#^^%#$ thing, and still had the problem. I even had the same codes. I went through the wire harness twice, and could not find a chafed wire. I ended up separating the "grey" connector wires from the rest of the harness, and insulating the top 1/4" of each connector in the ECM plug. It has stopped the problem for now, but I'm not calling it fixed yet. I finally deduced that I was having problems with 3 of my 7 wires on one side of the plug, so I ran it down to an ECM problem. Maybe that is a place to start, but with your problem above 4000-4500 RPM, I would STRONGLY suggest you check your grounds, and maybe run another from the engine to the battery. Up that high, your grounds need to be 100% or you will be stuck. With it falling to 3K after stall, it sounds like the ECM is going into a preserve, or fail-safe mode.

 

[Lando]

great, I'm starting to get that feeling like I'm going to spend all summer troubleshooting instead of riding.....

Anyway, can someone confirm i have the right part numbers?

08-10 Throttle position sensor #P0279.5AA
Bank angle sensor #65928-99Y

Thanks for the help....

 

[buellbradski]

I just read a few post on here about a cracked conection on the ECM. Apparently it's a common issue on the lightning and uly models due to ECM location. Take a quick look at your ECM