| Author | Message | ||
     Bengny |
Was out riding and went to take off from a light and realized I was now riding on one cylinder. Limped it home (backfiring the whole time) and there she sits. So given all the backfiring in the exhaust and the fact it came on suddenly (wasn't surging and sputtering, just dead) I figure fuel system is ok. Replaced the plugs, still nothing. Error code is front ignition coil. Weird thing is when I checked for spark both plug cables fire. I tested the connection as per the manual:   The test light very weakly flashes on both the front and rear so i don't think it's that. What am I missing? | ||
| Two_seasons |
Check your battery connections. 10mm and tight. If that isn't it, then bench charge overnight and see if that helps for awhile. | ||
| Arizona_buell |
Did you check compression? | ||
| Greg_cifu |
Did you get the light on the dash as soon as the problem started? Or did it throw the code later? You seem to have done all the other diagnosis correctly. The wire going to the front plug doesn't have any cracks or splits? A failure on the high-tension side of the coil normally wouldn't throw a code on the computer but, if ignition backs up and cross-fires inside the coil, it can freak out the computer (had that happen on a car and drove me nuts--new wires fixed everything). | ||
| Bengny |
Ok more info: Compression is good, it's definitely the front cylinder since the spark plug looks brand new and the rear looks tan (both are brand new plugs). Front plug smells of gas. I was wondering about the codes because some may have been stored codes? It's throwing: -Fuel Pump (may have been stored since I recently depressurized my fuel system a few weeks ago by unplugging the fuel pump and cranking) -Battery Voltage (because I've been cranking it through all these diagnostics) -Front coil -Intake air temp sensor (I unplugged that one to see if anything was weird on the sensor) The check engine light came on when I was riding it home on one cylinder, but I didn't read the code now until a few cranks and a week later because I figured the o2 sensor was probably going haywire with one cylinder dumping gas into the exhaust I checked the resistance between the ECM and coil, all connections are within spec so no shorts. Bad ECM? Bad Coil? | ||
| Oldog |
The test light very weakly flashes on both the front and rear so i don't think it's that. What am I missing? You have battery voltage @ b? IIRC both coils are making weak sparks? 02 is on the rear cylinder only and as you say the plug is fine, its not likely that the 02 is an issue, I think that the coil ( as you suggest may be bad, ( the ecm seems to be working if the lights are flashing for the test ) } | ||
| Bengny |
I actually don't quite understand the purpose of the test. Since you connect one end to the positive and a correct outcome is no flashing on the test lamp, is it supposed to test for an arc from the connector? There is normal battery voltage at 'b'. | ||
| Oldog |
Bengny The ECM is connected to A & C, the unit "switches the ground on and off". thats what you see with the test light. as per the test hook up the light and crank the engine if all is well the test light blinks. at rest the light may be ON, as you want to turn it off to cycle the coil to spark. check the condition of the wires at that connector, I have had some issues at the coil 12v connector. | ||
| Oldog |
while I am thinking of it the ECM has a ground ring IIRC check it make sure its good. I also presume that you have checked the plug wires and they are good? (Message edited by oldog on July 08, 2013) | ||
| Sparky |
Another test you can do to the coil is to check primary coil resistance while the coil is at room temperature - jot those readings down. Then heat the coil with a hair dryer while monitoring resistances. If the hot coil resistance varies from the room temp readings significantly then you likely have an intermittent failure on the coil. | ||
| Bengny |
The ECM is connected to A & C, the unit "switches the ground on and off". thats what you see with the test light. Well that makes a lot of sense since 'b' is powered. So the coil is bad then? Any other way to test it? Plug wires look ok to me. If the hot coil resistance varies from the room temp readings significantly then you likely have an intermittent failure on the coil. This is happening at ambient temp so I don't think it's that. So I got it to idle on both cylinders but as soon as I put load on the engine i lose the front. It doesn't recover either and will idle on the rear until it dies. I think I might need to pull the injectors and make sure the fuel is ok to the front? Problem with that is getting the fuel rail back on his a huge PITA! Took me over an hour last time! Only other thing I can think of is that I lose the spark at any kind of RPM above idle. } | ||
| Hootowl |
Measure the DC resistance of the input and output windings of the coil. Should be a near short. If it's failing at room temperature, you should see an open winding at room temperature if it's the coil causing your problem. | ||
| Oldog |
Plug wires look ok to me. I would be checking them with a meter I did not add the coil test as in my mind the lights blinking while testing tell me the ecm is likely good. the resistance test at RT will tell the tail, in that the front cylinder is not firing its likely that the thing is open.... } | ||
| Kalali |
Testing the coil is not always conclusive. You'll need to take measurements while simulating the real riding condition, e.g., heat, vibration, varying load, etc., etc. If it were mine I would replace the coil and call it the day. These bikes have very smart ECMs. | ||
| Bengny |
Update: So I wanted to really rule out fuel before I bought a coil. To that end I swapped injectors to see if the problem would move cylinders. Put it all back together and now it runs fine. So in the end I still have no idea what went wrong. Could've been a wiring issue since I disconnected and moved a lot of wires to get at the injectors. Bad clip or leaky injector itself. In any case the only thing to do is pray it doesn't come back. Thanks everyone for your replies and suggestions. | ||
| Natexlh1000 |
That's mental! I hate it when they fix themselves before I get a chance to do the deed. makes me feel useless. I'm glad you're on the road though! | ||
| Harleyelf |
Those coil wires have a habit of rubbing the frame and the gas tank. Next time it happens, see if you get the cylinder back by removing the seat and lifting the gas tank slightly. It is interesting that you shoved the suspect wires around to get at the injectors and then they self-repaired. |
