| Author | Message | ||
     Midnightrider |
Had recurrent episodes of spark skip at 70-75 mph highway trips - often within 10 miles. Read a ton of threads here and checked all grounds and electrical connections. Getting ready to replace the engine temp sensor when I found some threads on folks having the same issues with cracks in the ECM or pressure on the ECM connections. Also read some threads about changing (retarding?) the timing. My question is, what else could I check before going the time and expense of changing the engine temp sensor? I don't have a working copy of ECM-spy but if I did would that show me anything useful? There have never been any trouble codes when I jumper the pins in the DIY trouble code mode Thanks | ||
| Ratbuell |
Don - I have both a working copy of ECMspy as well as a spare stock '06 ECM if you want to try swapping a "known good" computer into the bike (I have it as a spare because I run an Erik Buell Racing computer now). If you're out Fredneck-way, drop me a note and we can take a swing at it  | ||
| Midnightrider |
Thanks Joe. I really no nothing about ECM spy - will it show a history or anything that might help diagnose this? And are you going to be around today 'cuz I'd really like to get to the bottom of this (Message edited by midnightrider on October 31, 2010) | ||
| Ratbuell |
I should be around today, sure. I'm not all that well-versed with the Spy either, but I think it will do some datalogging and can tell if your sensor goes out of spec, without throwing a code. May be an easy fix, though, just check the connectors on your ECM real close and see if they're cracked. Push down on each one like the seat is pushing on it; if one moves, you've got a crack. Send me a PM if you want to head out this way, I'll get you my address so you can plot the trip. | ||
| Midnightrider |
pm sent | ||
| Midnightrider |
My thanks to Joe for taking time to hook my Uly up to his ECM-Spy. Interestingly enough the bike didn't go into spark-skip on the way up to his place or the way back - despite two 20 mile stretches of 70+mph speeds. Everything he could see checked out fine. He also asked if I noticed the spark-skip when fuel was low - thinking maybe an overheating fuel pump. That's probably not it as I got the low fuel light only a couple miles after I left his place. It did die once when I was backing out of his driveway which makes me think there's a bad connection somewhere. Or it could be two separate issues. Anyway thanks again Joe. Between the uneventful ride up and the healthy ECM check I had a little more confidence in the bike riding back home and really enjoyed the trip. Funny how that can effect your riding - rode a bit more aggressively going home taking the corners a little faster, accelerating a little harder and generally just enjoying the hell out of it. A great note to end the weekend on heading into a tough week at work | ||
| Jlnance |
Midnight, the next time you have problems with it, pull the fan fuse, and see if the problems go away. I would be very interested in knowing. | ||
| Midnightrider |
Jim Willing to try anything but wondering how that would help. Seems to me that either the ET sensor is bad or the sensor is fine and the engine is actually running too hot. But again - willing to try anything. When talking to Joe today he related how Vern (Etennuly I think) had similar issues until he actually hardwired the fan Don | ||
| Ratbuell |
Another note, when I had his Don's bike hooked to the computer, the ET sensor was linear with no spikes or hiccups at all. TPS looked good, AFV was damn near perfect...I felt bad he had to run all the way out here for "nothing", but glad it behaved on the way home as well as on the way out. I suspect the dying in the driveway was because we'd (I'd) started and stopped it four or five times when running the diagnostics... | ||
| Etennuly |
Everything you noted was always right on with my bike also, I changed out my ECM for a known good one, and did the ETS and many other things including advancing the timing a few degrees. Many of these things done individually fixed the problems.....temporarily. The only fix I have had thus far is manually switching the fan on and leaving it on. It is running better than ever as it had all summer. What was the temperature when you rode out to Joe's place? Mine never did it below 65 to 70 degrees F. Oh yeah.....inspite of himself.....that Joe fella really is a good guy!  | ||
| Ksc12c |
+1 on the Manual Fan Switch. I ran Two up all over the Texas Hill Country with Temperatures in the Mid 80's. Not a single skip/spark issue. Kevin | ||
| Midnightrider |
Ok guys - I'll have to do a search and see how you hard wired it - especially with regard to the two speeds. I'm trying to get my Electronics 101 brain around understanding why it works to hard-wire it. I'm assuming the temp sensor tells the fan when to turn on so I don't see how hard-wiring it to an always on position changes that - unless the act of hard-wiring somehow changes some sort of electronic decision-making pathway through the ECM. Don't get me wrong - I'll do it anyway - it's just my nature to want to understand the "why". I'd also be concerned that hard-wiring somehow defeats the spark-skip protection mode and that maybe the temp is too high but the rewiring prevents spark-skip when it really should be happening. Like I said, I would have that concern if both of you hadn't already done it for some time with no obvious fallout. In the end I won't really care why provided it just plain works Don (Message edited by midnightrider on November 01, 2010) | ||
| Ratbuell |
My impression on the hard-wiring is, the running fan actually keeps the engine cooler, preventing the skip-spark from occurring. Again, though...my '06 hasn't skipped yet so it's all hearsay for me. I do know the comfort kit flash from the '10 Buells (and from Erik Buell Racing, if you have an '08-up) includes a much longer, more constant, fan runtime...so there may be something there after all. A running fan is an air-funnel...a stopped fan is an air-block (relatively). And don't listen to Vern. He's a painter - too many chemicals, he doesn't think straight anymore.   | ||
| Jlnance |
Willing to try anything but wondering how that would help. I've got this written up in another thread somewhere, but I can't find it, so my apologies to who ever has to read this twice. I had the skip spark problem once early last summer. I thought it was a fluke, as it just happened on a single trip down the interstate. Later, I took a trip to Wisconsin, and I lost the fan while I was up there. I didn't realize it was the fan right away, I thought it was the exhaust valve actuator, so I rode it the rest of the day, around Wisconsin, and then started the trip home. I probably rode 800 miles that day, sun up to sun down. It was 90 something degrees. I didn't have a fan, and not once did I have problems with skip spark. I lost the voltage regulator that night in Ohio (perhaps because of the lack of fan, but they are prone to go out anyway.) I limped it home, and replaced the battery/vr/stator. I rode it around Raleigh for a couple of days, again in 90 degree heat, before I realize the fan wasn't running. I had no problems with skip spark. I put a new fan in the bike, and on my first trip had skip spark problems so badly I didn't think I was going to make it home. This makes me suspicious that the fan causes the problem. If you look at the wiring diagram, the fan current flows through the ECM ground. If that ground connection (2 pins on the ECM connector) isn't good, it will create voltage fluctuations on the ground wire which will confuse the ECM. I unplugged the ECM, plugged it back in, and the problem has not returned for me. This is consistent with the problem being related to the ECM ground. Another person (sorry, I forget who) has solved his skip spark issues by wiring the fan so that it runs all the time. One thing this does is route all the fan current, which was flowing through the ECM ground, directly to ground so that the ECM no longer has to sink that current. This is consistent with the issue being a grounding problem. It is also consistent with the issue being temperature related. If we pull the fan fuse, so that the ground current goes away, but the temperature goes up, it should become apparent if the problem is caused by temperature or fan current. | ||
| Etennuly |
I wired mine to a manual switch on the bars. It comes on when I tell it to, which is about five minutes after starting and pretty much at shut down. It does keep the engine cooler by running all of the time. I like the theory about the ECM not being able to handle that much voltage to ground, it makes perfect sense. Mine also did not do it with the original fan very often, only months after the replacement fan did it get carried away and do it's thing all of the time. That is a heck of a lot of voltage to pass through an ECM. It does not matter that it is the ground or positive lead, as long as it is directly in the circuit for the fan it takes all of the voltage through the ECM. Perhaps this is why every aspect of the bikes running works better with the fan on a separate circuit. | ||
| Midnightrider |
Thanks Jim I can understand most of that. And thanks Vern. I have an unused toggle switch already wired and cut into the handguard. I used it for a hardwired HID upgrade to avoid the initial high current draw for the HID start-up until I realized i kept forgetting to turn the lights on during the daytime. I head out of town tomorrow night but I'll rewire the fan when I get back. It might be a while before I know if it made a difference though - because as Vern points out it doesn't seem to happen with ambient temps below 60. One last question though - would running the ground from the fan to the negative battery terminal instead of the ECM ground work? Would that head off any voltage fluctuations to the ECM or would there still be possibilities of voltage fluctuations to the ECM through the feed? Or would that somehow prevent the ET sensor from telling the fan when to come on? As I think about it, this is my third fan. The first flat out died. The second one I replaced a couple years ago but I'm not really sure why. I think I was getting a spark-skip and assumed the fan wasn't running like it should at speed although it was running when I shut the bike off ( I have a drummer so I can't always tell if the fan is running when I'm riding on the highway)? Ratbuell and i did check the ECM connections pretty good last Sunday when it was hooked up to the ECM-spy but again, it didn't spark-skip on that day before or after the diagnostics Thanks | ||
| Ratbuell |
I'd have to look at a diagram, but I think the ECM switches the ground as opposed to switching the hot. I think. Now...would any of the "hardwire" guys want to try going back to OEM, but instead of the ECM being wired to the fan, having the ECM trigger a relay that feeds a hard ground to the fan, avoiding the current draw through the ECM? You'd have to wire the relay "backwards", grounding the relay to battery hot and using grounds for the other pins...but in theory, it oughta work? But if it works, you get the best of all worlds - ECM-switched fan, without the wonky current draw... | ||
| Etennuly |
You are right it switches the ground. As far as electric motors go.....is it not harder on a motor to continually turn it on and off, sometimes subjecting it to fairly extreme heat, verses say leaving it on to keep not only the engine cool, but itself also? At the same time it no longer has voltage spikes that are required to start the fan's armature spinning. I don't know. It seems to me that by running it nearly all of the time versus frequently coming on and off it might last longer, as in to have it actually wear out rather than burn out. But then considering the actual longer run time it may equal out. | ||
| Ratbuell |
My thought on continuous runtime is hotter bearings....and (ducking the incoming flames) we all know about Uly's and bearings!  But seriously though, the fans that fail aren't burning out the windings as far as I know...they're eating the bearings. I know my fan has sounded like a bag of marbles for almost a year now; spare fan lives in the topcase | ||
| Garrcano |
I wired the fan through a relay, so the fan function stays. This way the engine temperature is controlled as before by the ECM without messing it with the 3 amperes. At the moment it seems to work I will wait for the next hot summer here. I don't think in my case the spark skip is gone due to a cooler engine, it's gone because the ECM has less current top handle. My opinion is that there is a moment where the ECM gets too hot to handle the current for the fan, which maybe starts to rotate slower and the engine gets hotter causing then a hotter ECM and so on till spark skip. | ||
| Jlnance |
would running the ground from the fan to the negative battery terminal instead of the ECM ground work? The ECM switches the fan on and off by grounding the negative lead of the fan. If you ground it, it will simply run all the time. Which may not be undesirable... The only problem with running the fan via a relay is that you loose the low/high speed operation of the fan (the ECM accomplishes this by switching the fan on and off very rapidly, more rapidly than the relay will respond to.) If you don't mind that, the relay is a great option. | ||
| Garrcano |
The only problem with running the fan via a relay is that you loose the low/high speed operation of the fan (the ECM accomplishes this by switching the fan on and off very rapidly, more rapidly than the relay will respond to.) If you don't mind that, the relay is a great option. It seems that the relay is fast enough, because the low/high function is still working (for my surprise). Farnell Parts Numbers: 1629093 Relay Socket Tyco V23333Z0002B049 1197662 Relay 12V SPCO Tyco V23074A1001A403 (which is compatible with the OEM relay) I use diodes for protect the ECM and for protect the contacts of the relay. | ||
| Midnightrider |
Garrcano I'd like to know how you made the mods. Maybe you could post it here or PM me. One more thing I don't understand about the whole voltage fluctuation theory is how that could explain the spark-skip only with higher speeds. Seems like the fan is probably already running when the spark-skip happens and even if it wasn't, I would think it may be enough to cause a single episode but doesn't explain to me why the spark-skip goes away instantly with a 5 mph decrease in speed then comes right back with another 5 mph increase. Like somebody said earlier, I guess if it happened and I stopped real quick to pull the fan fuse and got going again I wouldn't expect the spark-skip to persist after a few minutes at higher speeds. Maybe? | ||
| Garrcano |
http://www.badweatherbikers.com/buell/messages/142838/562277.html Actual version installed on my bike:  | ||
| Midnightrider |
Thanks a lot! Now I just have to get someone to interpret that for me. Fortunately, I have a trio of geeks here almost every weekend. My daughter (biophysics major/engineering minor), her beau (physics) and my nephew (engineering). And I'll save you the trouble - they obviously didn't get their brains from me. They all go to school in the area and have taken to crashing here almost every weekend. Looks like I finally have a chance to get a small return on the $2000 worth of groceries they've cost me over the last year Thanks again (Message edited by midnightrider on November 10, 2010) | ||
| Chief_sitting_buell |
I'm having the same problems and wondering if this would work - leave the fan plugged into the harness but cut the ground. Then install a switch with three terminals. I don't know the right terminology but I've seen such a switch. Run the ground wire from the fan to one terminal (call it post one)then run a wire from another switch terminal (call it post two) to the other end of the cut ground that goes back to the ECM. In this configuration it would be essentially like OEM. Then take another ground wire and run it off the third terminal (post 3) to ground on the battery terminal. When switched to this position, the path to ground would be always on and the fan would run continuously. In this way I could run in the OEM configuration until if/when it goes into a spark/skip mode caused by voltage fluctuations and not actually high head temps. When the spark skip happens I could flip the switch while maintaining speed 0 the path to ground would be always onm the fan would run and the ground wire back to the OEM would be carrying no current ( since the switch position interrupts that path). Post one ( from the fan) is always fed - toggling the switch just shunts the path to ground between either the ECM ot the battery terminal. Besides maintaining the ability for the ECM to turn the fan on when needed and maintain the two speed function when everything worked correctly, the configuration would also be diagnostic because if it went into spark skip and I switched it so the current flowed directly to ground and kept the current from flowing back to the ECM, it shouldn't go into spark/skip caused by voltage fluctuations ( and the fan would stay on for max cooling) Or is all this faulty logic since the ECM would still be sending current to the fan? I guess I would need to know if the voltage flux that fools the ECM into going into spark/skip is caused by sending current to the fan or receiving current back from the fan to ground. I hope this makes sense. It does in my mind - but that's gotten me into trouble before. Thanks |
