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Offline AKTiger123

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Engine running lumpy under load
« on: July 05, 2021, 04:42:02 PM »
Hi  - i have a tiger 800 xca  - 2017 about 7.5k on the clock, which has recently had a service,  during the service on a test run the mechanic came back and said it was a bit lumpy under load (acceleration).  Also a few days prior to this i felt it was running a bit hot (it was also a very hot day).  The mechanic said that there was no electrical errors and also no engine lights on so thought it could be a fuel issue - asked if it had been sat around for any extended period which it has not.  He advised changing the fuel and using some fuel injector additive which i have done but no improvement in performance.  Its perfect on idle and through gears 1 - 3  4th under powered  but when in 5th and throttle hard it feels like it is at half compression same in 6th .  I have measured the exhaust manifolds with a heat gun and one seems to be getting hotter then the others - is this a blocked / poor performing fuel injector?

any ideas similar issues found,  thanks

Offline awjdthumper

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Re: Engine running lumpy under load
« Reply #1 on: July 05, 2021, 05:33:45 PM »
Car ECU's are capable of detecting cylinders which are 'misfiring' but, unfortunately, this function does not appear to be built into motorcycle ECU's. However, one downpipe being a different temperature probably represents the cylinder 'misfiring'.

The problem could be the injector or the coil (or something less accessible) and it may be a case of swapping them in turn with those from another cylinder to see whether the hot exhaust moves to the other cylinder. A bit of a phaff to do though!
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Offline AKTiger123

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Re: Engine running lumpy under load
« Reply #2 on: July 05, 2021, 07:40:45 PM »
Thanks for the advice will give it a go,  would a coil run bad under load but be OK on idle and through the lower gears? the other thing, could it be a mass flow sensor issue? is this easy enough to check?

thanks

Offline awjdthumper

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Re: Engine running lumpy under load
« Reply #3 on: July 05, 2021, 10:12:24 PM »
With a motorcycle, problems of this sort are always hard to narrow down but, in this case, the hotter downpipe is hopefully pointing to a fault with a particular cylinder. If that is the case then it is unlikely the problem will be with the MAP (manifold absolute pressure) sensor which would affect all 3 cylinders.

A faulty injector or coil might well well create a big effect on engine running the more load you put on it and might well be ok during idling. In principle, you can test both the injectors and coils to some extent off the engine but it might be worthwhile doing the swapping first to see whether the hot exhaust is indicating the problematic cylinder.

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Offline AKTiger123

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Re: Engine running lumpy under load
« Reply #4 on: October 19, 2021, 04:11:33 PM »
Hi all - just thought I would give an update on this - well it was running lumpy for a while but was improving having put some Motul Fuel System cleaner (for Bikes)  through it and took it on some long rides at a constant speed of 70 mph with the occasional blip and some high reves getting through the gears.  I also changed the plugs, air filter, filter box seal and chamber sponge as these were probably the originals as the bike has only covered around 8.5k on a 17 plate.

I also checked all of the resistance on the coils primary and secondary wind, all in spec and identical, injectors resistance all the same, reed valve opening and closing and cleaned the MAP and ATI sensors, checked all hoses whilst tank was off.

Bike was still not perfect but getting better - then took it for a long long ride with another can of Motul in the tank to the Isle of Wight and back over a weekend plenty of miles and constant motorway speeds getting to and from the ferry on the mainland.  Since then the bike has been perfect - I can only conclude that it was a fuel contamination problem  - never had an engine warning light and never any codes stored. I think the longer rides allowed things to get cleared out and then the bike learn and adjust the fuel air mix etc as it worked its way through.

Thansk for all of the advice and guidance and hope this may help someone else!

Online Stevie.P

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Re: Engine running lumpy under load
« Reply #5 on: October 19, 2021, 04:44:06 PM »
*Originally Posted by AKTiger123 [+]
I think the longer rides allowed things to get cleared out and then the bike learn and adjust the fuel air mix etc as it worked its way through.

Hi, if it was my bike, following your latest post, I would do a 12 minute adaptive reset and let the bike relearn fresh from factory settings. :028:

https://www.tiger800.co.uk/index.php/topic,26838.msg292578.html#msg292578
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Offline AKTiger123

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Re: Engine running lumpy under load
« Reply #6 on: October 19, 2021, 05:25:55 PM »
Thanks StevieP - will definitely give that a go!  Cold start, don't touch throttle, run for 12 mins once first cycle of cooling fan hits,  - got it :152:

 


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