This is a new bike to me this spring but I still don't have 30 miles on it. The problem is just that, starts fine, runs good cold, but after 5 minutes one cylinder starts becoming intermittent. A timing light narrowed it down to the rear cylinder spark becoming flakey. I've already replaced the coils, ignition wires and caps. Timing is spot on, gas is good. I did find one of the hoses off on the gas tank, an air bleeder but it made no difference. Also found one of the coil's two slip on terminals were reverse wired, made no difference. Also found a mouse made a nest in the air cleaner, a new one made no difference and I added a wire mesh to the air box intake. Any ideas?
Rear cylinder cuts out under 4000 when hot
- Thread starter pmok
- Start date
The bike isnt blowing any codes? No arcing at night ? Doesnt really sound like a crank/cam position sensor but I wouldnt rule them out. I hate to sound like an idiot but I would get at least one or two cans of freeze mist and start hitting parts once the bike is misbehaving. It sounds like you can "see" the issue with a timing light?
Any other wires that the friendly rodent nibbled or did any nest material make its way further in (unlikely if air filter in place though).? Would check wiring very carefully and also all the ecu connections hiding under the tank area. Could possibly be a fuel or fuel supply issue if the bike had been stood a while but really on the NT700 would not expect only one cylinder to be affected. Certainly sounds electrical in some form......
I don't have the error code reader and the dealer is an hour away, so I bit the bullet, ordered a replacement used ECU off Ebay. Magic, that seemed to cure about 99% of the hot rear cylinder intermittent issue. Shotgunning at this point, it was the 5th part I've replaces... Still an occasional loss but I could ride it to the gas station!!
Great bike otherwise. Now I'm looking into a windshield extension as I'm over 6' and the wind buffetting my head is very loud above 60.
Great bike otherwise. Now I'm looking into a windshield extension as I'm over 6' and the wind buffetting my head is very loud above 60.
I bought a taller wind screen as I am over 6 ft but I use a tall windscreen and an extension on my VFR. My memory is fuzzy but I dont think the Nt requires a code reader.
BTW, did you exersise the ECU pins before relacing the box?
[How To] - Read & Reset MIL | How To's
Read & Reset Maintenance Indicating Light (MIL), aka Check Engine Light (CEL) Before STARTING the NT, verify the MIL light has cleared after the short self-check. If the MIL stays on after the short self check, don't start the NT or cycle the ignition switch to clear the MIL. If the MIL is...
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Before STARTING the NT, verify the MIL light has cleared after the short self-check. If the MIL stays on after the short self check, don't start the NT or cycle the ignition switch to clear the MIL.
If the MIL is present after the short self-check before starting the engine, read the MIL code by:
-shifting to neutral
-release clutch
-lower kickstand
Read MIL flashes. Long is ~1.3 seconds & counts as 10. Short is .5 second & counts as 1. If there is more than one code, it should blink one code then the next in numerical order (not chronological order), then it continues to repeat flashing the codes.
If the MIL clears as normal after the self check, but the NT is hard to start & no MIL as come on, crank to start for >10 seconds & a MIL should come on. Then while the MIL is on, do the above to read the MIL flash codes.
If you notice a MIL when riding, pull over and don't turn engine off. If the engine dies because of the MIL, don't turn the ignition off. Read the MIL flash codes by performing the following steps.
-shifting to neutral
-release clutch
-lower kickstand
Read MIL flashes. Long is ~1.3 seconds & counts as 10. Short is .5 second & counts as 1. If there is more than one code, it should blink one code then the next in numerical order (not chronological order), then it continues to repeat flashing the codes.
How to read MIL codes stored in ECM.
If you see a MIL, the code for MIL will also be stored in your ECM even if the MIL has since cleared. If you want to read the fault for a previous event when the MIL was on but it has since cleared, do this:
-Ignition switch off
-Remove seat and left side cover.
-Remove the red cap off of the Dummy Load Connector (DLC). It's the 4 wire connector with the red cap just forward of the ECM (main computer card).
-Insert a shorting wire into the Brown and Green wire's terminals of the DLC. I use a ~4" long speaker wire. Any small wire should work. Don't jam a big wire in there.
-Verify engine kill switch is ON.
-Turn Ignition switch ON
-Read blink codes on MIL
If there is more than one code, it should blink one code then the next in numerical order (not chronological order), then it continues to repeat flashing the codes.
-Turn ignition switch off, remove shorting wire, replace cap & side cover & seat.
How to clear the codes in the ECM.
The ECM doesn't save the previous fault codes in chronological order. Because of that, it is a good idea to clear the codes & keep the register empty so that in an event of a new MIL fault code occurring there won't be other codes stored in the ECM to confuse any future troubleshooting. If you are concerned about having proof of past codes (ie ...to show a shop) I would suggest videoing your old codes flashing. To clear the codes:
-Ignition switch off
-Remove seat and left side cover.
-Remove the red cap off of the Dummy Load Connector (DLC). It's the 4 wire connector with the red cap just forward of the ECM (main computer card).
-Insert a shorting wire into the Brown and Green wire's terminals of the DLC. I use a ~4" long speaker wire. Any small wire should work.
-Verify engine kill switch is ON.
-Turn Ignition switch to ON.
-Temporarily remove the shorting wire in the DLC plug. The MIL will have a solid yellow light for 5 seconds, reinsert the shorting wire into same Brown/Green wire terminals on the DLC during the 5 seconds.
-Verify MIL goes OFF, then starts blinking. The ECM memory is now cleared. If you're unsure that the codes were cleared try reading the stored codes in the ECM from steps above.
-Turn ignition switch off, remove shorting wire, replace cap & side cover & seat.
MIL blink codes for the NT
1 MAP (Manifold Air Pressure) Sensor Voltage high or low
2 MAP Sensor performance problem
7 ECT (Engine Coolant Temperature) Sensor voltage high or low
8 TP (Throttle Position) Sensor voltage high or low
9 IAT (Inlet Air Temperature) Sensor voltage high or low
11 VS (Vehicle Speed) sensor lost
12 #1 injector malfunction. Will not start.
13 #2 injector malfunction. Will not start.
18 CMP (Cam Position) sensor lost. Will not start.
19 CKP (Crank Position) sensor lost. Will not start.
21 O2 sensor malfunction
23 O2 sensor heater malfunction
29 IACV (Idle Air Control Valve) malfunction
Last edited: Jun 6, 2019
Dan
Yelm, WA
2010 Honda NT700V Red, 2015 Honda CB500XA
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Great info Mr Coyote, Looked at all the wiring and tubes for any mouse nibbling, saw nothing.
I have new plugs but the special wrench hasn't arrived yet so there may still be a plug issue to discover.
The MIL goes out as it should and does not produce any error codes from memory for either of the ECU's.
The engine starts easily with either ECU's, always has. I believe only the initial ECU has a heat problem after 5 minutes. But with a plastic housing I don't think the freeze spray trick will give us a useful test.
Before I got the second ECU I removed both ECU connectors a few times to "scrape the contacts", they all looked clean.
I have new plugs but the special wrench hasn't arrived yet so there may still be a plug issue to discover.
The MIL goes out as it should and does not produce any error codes from memory for either of the ECU's.
The engine starts easily with either ECU's, always has. I believe only the initial ECU has a heat problem after 5 minutes. But with a plastic housing I don't think the freeze spray trick will give us a useful test.
Before I got the second ECU I removed both ECU connectors a few times to "scrape the contacts", they all looked clean.
Excellent. As an electronics tech. you are doing well. BTW, I found my wife's bad cam position sensor on her Subaru with freeze mist. It is right out in the open under the hood. So I "set it up".
I drove the car till it was very warm and then stopped it in a parking lot. It wouldnt start. So, quick like a bunny, I openned the hood and sprayed the sensor with freeze mist for five second and the car started right up. It took all of a minute to replace the sensor. (Subaru has a contest every year to find a new place to put the sensor...luckily...mine was on top of the engine driver's side when they had the old cam belts your had to replace.