Hitchcocks Forum

Hi again. B5 EURO-4 started misfiring a few rides ago at low throttle settings but runs OK at higher throttle. Has got progressively worse but no MIL light initially. Today, missing badly at low settings so I stopped and switched off. On restarting MIL light permanently on but strangely misfiring had disappeared on 15 mile ride home. Dignostic blink test shows 6 short blinks of MIL - Throttle position sensor. Have measured output voltage from sensor 0.59v at throttle closed and 3.77v fully open which seems to match specification. MIL light still on and stays on after attempt to reset. Advice on what to try next much appreciated. One odd observation which might be irrelevant - a couple weeks ago for some reason I started the engine with bike on sidestand. The MIL light came on but it did start (thought it wasn't possible). The engine ran roughly for a mile. On stopping and switching off, MIL light went out and normality resumed until the misfiring this past week.

This sounds similar to the symptoms mine had when the reg/rect was failing. Worth checking - lots of how to videos on YouTube, it's the same for any modern-ish bike. You need a multimeter though.

MIL glows continuously, engine WILL start.
LONG 0 – SHORT 6 TPS
LONG 0 – SHORT 9 MAP sensor
LONG 1 – SHORT 1 Oil temp. sensor
LONG 1 – SHORT 7 O2 sensor
LONG 4 – SHORT 5 O2 sensor heater

I think you need to double check every connector.🔧

Am I missing soemthing here? - the bike can barely be a few months old - take it back to your dealer - its under warranty !

What Haggis said. My C5 had the same symptoms; it turned out to be a loose connection between the TPS and the main wiring loom. FWIW the fault code showed a faulty crank position sensor according to DOL ( the dealer’s diagnostic software). Apparently this fault code can occur even though the fault lies elsewhere. I was told that this is because without for example a working TPS input the ECU has no idea how to fuel the engine so it displays a serious fault. This may be rubbish but remaking the TPS connection remains bed the crank position sensor fault. Whatever, check all the sensor input connections.

Hope you can make sense of that - bl**dy predictive text...

Rattlebattle - I am never sure whether your typing errors are just errors or indicative of your colourful language. Could take back to dealer but it's in central Glasgow (50 miles away) and logistics not easy so it's a last resort. Checked all connections and output from TPS within spec. MIL light still on when engine started. As I said earlier, I was suspicious about the sidestand circuit. On the Euro-4 you can start the engine with sidestand down but it cuts out when gear engaged. But the MIL light had com on when I had done that a few weeks ago and the handbook says not to do it. So, using homeopathic logic (crap), I repeated the exercise starting bike with stand down and the MIL light went out and stayed out on repeated start-ups. Yet to road test. Very weird.

On the new E4 models and Himalayans - you need 3 cold starts for the MIL lamp to go out, it may not cancel straight away. I took the tank off mine and when refitted - the MIL lamp came on - after a couple of starts - it went away, you may have fixed the problem and not know it yet.

Predictive text issue.... Anyway, one of the first things I did on my 2015 C5 was to disable the sidestand switch. Just about every forum I’ve been on for different makes of bikes has mentioned problems with misfiring attributable to this, in my view unnecessary, annoyance. Inevitably the switch gets covered in all sorts of road filth until it contacts only intermittently. FWIW my nearest dealer is now a fair way away, the supplying dealer having given up s year or so back. Coverage in the U.K. is pretty patchy I’m afraid.

My new 2018 Euro 4 C5 didn't even make it the 30 kms home from the dealer before it stopped. No MIL light. It continued stopping (the engine that is) at irregular intervals sometimes going for 50 kms before stopping and other times stopping every couple of kms. It always restarted, but this is not much help on the highway with a B double truck behind. After 3 trips back to the dealer, when he had the bike longer than I had, they had 1. removed the side stand switch (made no difference) , 2. looked for a fuel tank vent blockage (didn't make any difference) and, eventually, after it had been picked up for the 3rd time seemed to find a problem with the side stand switch relay and/or the ECU relay. Both of these were replaced and I was able to ride it home without stopping.
I believe both of these relays are in the LH side toolbox with the fuses. One of the problems the dealer had in trying to isolate a fault (no MIL light ) was the lack of a wiring diagram.... this being a new model. If it is still playing up you may want to have a look at these relays and make sure they are fitted correctly. This bike also has a roll sensor under the seat which is something to do with the ABS. Another bike had a problem with this which I think caused cutting out.