Issue: Cold Start and Idle rough

Discussion in '6th Generation 2002-2013' started by jsjamboree, Apr 24, 2016.

  1. Terry Smith

    Terry Smith Member

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    Well the good news is you can rule out valve clearance or cam timing as a cause of the issue.

    I did much the same thing with my ST1100, because it was running poorly on mid to high throttle, and it was nice to find that those things were in order at least.

    I don't think you should be finding any fuel on the valves when the engine is off. Fuel should only be sprayed out of the injector when that is opened by the ECM. Still, it seems unlikely that you have switched all the injectors and TB's and still have leaky injectors, but what do I know?

    As a dumb suggestion to narrow the cause, what if you were to unplug one sensor at a time and try the bike? My thinking was that if you felt it get worse/different, then whichever sensor you just unplugged is NOT your smoking gun. Whereas if there is no change, then that sensor wasn't working/connected correctly to begin with.

    Have you considered all the ground connections?
     
  2. jsjamboree

    jsjamboree New Member

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    I've almost felt that nothing makes a difference. Doing the idle valves, and screwing with different things during this journey, nothing has changed how the bike has ran. Almost as if it's in some sort of limp or safe mode. But I'm not getting any FI codes. It could still be the injectors but that would be some really shitty luck. I've got my trip this weekend that I seem to be borrowing a bike or just riding this one as is. When I get back I'm packing up all 8 injectors and shipping this out to find the best set.

    I checked the main ground circuit to the frame and the battery ground to the frame. That's all I saw in the diagram. Anything else I've missed?


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  3. Terry Smith

    Terry Smith Member

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  4. jsjamboree

    jsjamboree New Member

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    Never had the front fairing off, always seemed like it would be a pitta, guess i'll figure that one out now. This could make since (though im trying to make everything true at this point). I know my clock is pulling over 1.5 amps itself, which the book says is to much. If that's the ground for the gauges, chances are the clock plugs into there. I think this is a stretch, but i'll get to it tonight. Wife is starting to get angry that all my time is out in the garage the last two weeks. Not sure how much longer I can keep hiding out there :)

    Update for anyone who shows up to the party, current things done:

    1. had the injectors rebuilt, still had concerns so i ended up buying a throttle body assembly off a 'running' bike, same issues (not great troubleshooting as this new one COULD be bad too, but i would take the bet its not since the issue has remained)
    2. went through the ect, iat, map, tps and everything checks out, no FI error code lights
    3. gone through grounds and wire connectors and verified everything looks good, no melting or burnt wires
    4. new plugs, verified all plugs fire in the coils with blue spark
    5. found that the regulator/stator are on their way out, but even removing them from the equation and running the bike off a battery charger the issue persisted
    6. checked non-vtec valve clearances and they were in good (3 of the EX clearances were about 0.02mm to tight, but they could have been actually in spec Im really not sure how much tension is to much). Anyways good enough not to cause this amount of issue
     
  5. jsjamboree

    jsjamboree New Member

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    Checked the ground block behind the front fairing, looked spot on, connectors on the back looked good too. Can check that off the list.[​IMG]

    Got the new stator and reg/rec installed, I have a new temp sensor even tho mine is fine, I'll get that replaced tomorrow then I guess I'll try and fire it up. I can fiddle with different injectors between the two sets, but that's all I've got left. Taking tomorrow off work to get the last parts checked, Friday morning I'm suppose to be on the road.

    The only other think I can think of at this point would be ECU. Anyone have one laying around I can test with?


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  6. jsjamboree

    jsjamboree New Member

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    Did two more things today, first I checked the fuel pressure, it was at 36 at idle , so spot on, not an issue with the frp... Also swapped around the injectors and never made a difference.

    Next I hooked up a computer to my power commander... At idle i started leaning it out by -5 intervals, then I richened it up at idle by 5s.... Both directions made it run worse, so it's not a general fuel issue. I am just dumbfounded. It either has to be that the spark is weak at idle and that's causing it to not burn the fuel correctly, there is a valve that's not closing all the way (smells rich but never had raw fuel out anywhere), or... Who knows... Called the dealer they are booked out till August!


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  7. Jeff_Barrett

    Jeff_Barrett Member

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    Well ... if the injectors aren't leaking, then that narrows the field down to No / Poor Combustion.

    - No / Poor Spark
    - No / Poor Compression
    - ??

    Have you done a compression test yet on that cylinder? That will tell you if you have a compression (valve or ring issue) issues on the 'wet' cylinder and maybe narrow the field further.
     
  8. jsjamboree

    jsjamboree New Member

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    Just got back from a 1000 mile ride on her, issues still remained the entire time, was hoping that it would work itself out a little bit with all the of the things I have done. Ran an entire bottle of seafoam directly into the throttle bodies, hoped that if it was some carbon buildup on the valves that and the trip would take care of it.

    The best mileage I got on the trip was 30mpg, and was as low as 23mpg when I was hitting it hard. Everything still tells me that this is a fueling issue, but not a standard fueling issue since just increasing and decreasing the fuel at idle only made it worse. When I spoke to a mechanic at the dealer, he said he has never seen a bad ECU, but on my trip there was a mechanic (not Honda) he said he just had a bike in that had somewhat similar issues and it ended up being ECU... So there is that. I'll post up a new thread to see if anyone has an ECU I can borrow to test.

    Another guy on the trip said that his old bike was known to have timing chain stretching issues that would cause them to run retarded. Anyone heard of this with the VFR? I would think it could cause similar symptoms.

    I have not yet done a compression test, but that is the next thing on my list to do.

    Also thinking about pulling the injectors and rails, putting some small cups or bottles under and running the starter to try and see if I can notice anything odd about them, like one being stuck (everything keeps pointing to a stuck injector, but I have crossed that off my list some time ago)
     
  9. Jeff_Barrett

    Jeff_Barrett Member

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    I would do this ... if you have a buddy with an oscilloscope and knows how to use it, you can check the actual pulses to the injectors to see if the pulses are different.
     
  10. Knight

    Knight New Member

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    The 6th gen bike has two cam chain tensioners that require periodic replacement. Usually when they go bad they make an obvious knocking noise that may at first go away when warmed up. Are there any odd noises?
     
  11. Terry Smith

    Terry Smith Member

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    You should be able to do a timing check from the crank marks, usually there are marks on the cam sprocket that line up with the gasket surface. I've done this on my VTR and I did see 1/2 a tooth variation due to chain stretch (75000 km) engine, so don't be concerned if the line up is not exact.


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  12. jsjamboree

    jsjamboree New Member

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    I did this back when Knight was talking about the cams being off a tooth. The two cams line up well, the timing back on the crank was off just a smidgen. I really dont hear any slapping type sounds and the chains were tight. If this isn't something anyone has heard of then its likely not my issue. Been in the garage or on trip every day for the last 1.5 weeks, it'll be a few days before I get back out to mess with it. I'll have an update here shortly about what i see with the fuel and compression.
     
  13. Jeff_Barrett

    Jeff_Barrett Member

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    Could be one of the sensors that impacts the A/F mixture is bad but not throwing a code - this can happen too.

    It's just odd that one cylinder is wet compared to the others.
     
  14. jsjamboree

    jsjamboree New Member

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    I checked the MAP sensor, it tests correct, I replaced the temp (ECT sensor) because I was already in there, and tested the IAT and TP sensors, and bypassed (and hooked up) the O2 sensors. Thats really all I saw that should effect it. The only other thing could be the crank position sensor? That wouldn't effect fuel though
     
  15. Jeff_Barrett

    Jeff_Barrett Member

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    I'd need to look at the sensor diagrams but I think you got them all.

    Is the VTEC sticking open at low speed?
     
  16. jsjamboree

    jsjamboree New Member

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    Nope, its noticeable when it kicks in at 7k RPM
     
  17. Jeff_Barrett

    Jeff_Barrett Member

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    What if it is sticking open on one cylinder though? Just a thought - though that wouldn't necessarily mean that it's pushing more fuel in since these are injected ... ? just thinking out loud to myself. haha
     
  18. jsjamboree

    jsjamboree New Member

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    I can tell for sure the intake valves are not open, because I have spent a lot of time with the throttle bodies off looking in there. Obviously can't tell on the exhaust. I'll get a compression test done here maybe this weekend and that'll let me know for sure its not a stuck valve or a valve not closing all the way.
     
  19. Jeff_Barrett

    Jeff_Barrett Member

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    Wish I could get my hands on this bike.

    There's only 2 things that cause a plug to be wet with fuel - rich fuel mixture or fuel not burning.

    It's going to be one of those two things. Unless it's not fuel and it's oil or something else ..
     
  20. jsjamboree

    jsjamboree New Member

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    Been awhile since I've looked at the bike. Finally decided to get back out there. Took the injectors out of the manifold, put little cups under them, flipped the kill switch and the pressure blew two of the injectors out of the rail, so obviously that isn't something you can do to test. O well. I pulled all of the plugs again since it went about 1000 miles, and they all look fine. At this point I'm back out of possibilities. [​IMG][​IMG][​IMG][​IMG]


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