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Discussion Starter #1
Hello,

My bike (2008 RC8) started running rough a few months ago so I pulled it apart for Winter to do a full service, valve clearances etc.
I didn't have TuneECU before so didn't get any fault codes but now that it is back together it is still running rough (possibly differently than before as can't ride it?)
P0638 code - 2nd Throttle control - system malfunction.

I had the TB's dismantled to clean the injectors (all OK) and it looked very logical to reinstall so I don't think I've done anything wrong. Throttle play adjusted and seems fine, (max TPS 95.4 but I understand that is normal), I cycled the 2nd butterflies using TuneECU.
TPS reading 0.591v which is between the 0.56 - 0.64v 'Zero' position and I didn't move the TPS anyway.

The map was 2009 Standard with o2 & SAI (it originally ran fine despite Jester exhaust & SAI removed) but I loaded the 2009 (all models) Akrapovic map with o2/SAI off then did the 15 min reset but no improvement.

Any ideas?
When I look at the rear 2nd butterfly it is closed and the front one is open when the bike is not running, is this normal?

I did a search but didn't find anything that helped.
Thanks,
 

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Discussion Starter #3
Thanks, I've been told from other sources that both 2nd butterflies are supposed to be closed when the engine is not running so it's likely that I have indeed assembled the TB incorrectly, they were off the bike for a few weeks and split and I couldn't remember if one open & other closed was correct since the rear one can electrically motor independently. I'll fix that first and it should clear the code.

Whilst the TB's are off again I might try filing down the actuation arm to see if i get get 100% Throttle position rather than 95%, I read a post about it somewhere, anyone else done that?
 

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Whilst the TB's are off again I might try filing down the actuation arm to see if i get get 100% Throttle position rather than 95%, I read a post about it somewhere, anyone else done that?
I filed down the stop to reach 100%, and the primary butterflies at that point are vertical.

In the grand scheme of things, I've no way of knowing how much difference it makes as I've yet to get the thing on a dyno.
 

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Discussion Starter #5
Thanks I think I’ll file down the stop a bit when I have the TB’s off next week as I’ll have them apart again.
 

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Discussion Starter #6
Update - I reassembled the TB’s and the P0638 code has cleared but the bike is still running as rough as before, Grrrrrrrrr.

It‘s now giving a P016 fault code (coolant temp sensor 1) so I’ll have a play around with that although I can’t see how that could make the bike run badly, hunting between 2-3000rpm, back fires and cuts out sometimes.

A few months ago it started running really rough and misfiring so I limped it home and did the following:

Adjusted the valves (2 slightly tight) - turned it over by hand loads of times and checkEd alignment still OK & both tensioners ‘popped’.
Drained tank and cleaned tank fuel filter, fresh 98RON fuel
Had the injectors cleaned and tested
The original map was 2009 with original exhaust (092001) and it was running fine for 2 years despite having a Jester, SAS/o2 active despite having SAS removed. I’ve now removed the o2 & fitted bungs, turned Off SAS/o2 and tried both 08 & 09 2031 maps (Akrapovic). I didn’t fit o2 eliminators to the loom just turned them Off in Tune ECU. I read the bikes map again to make sure all was correct.
TB‘s now reassembled, used TuneECU to actuate secondary butterflies, TPS voltages within range. The TB to air box rubbers were all torn up so I replaced with new (originally I thought that was the problem).
New spark plugs
New clutch plates, oil/filter, air filter, suspension - unrelated to running.

Surely if a coil was on the way out then it would throw an error code, I don’t really want to buy expensive spares that I don’t need just to try things out.

Any ideas as it’s starting to drive me mad! What have I missed?
Did the 2008 RC8 have any foibles that I’m unaware off?

Thanks.
 

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Discussion Starter #7
Also why is the Idle so high and hunting between 2-3000rpm?
How would I correct this?
 

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One thing at a time is best. Sort the ECU error code first, check for pinched wires, damaged or unplugged connectors. If you fix it clear the code and try again.
 
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