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New spark plugs, now it runs like crap until FI light comes on

  #1  
Old 09-19-2011, 11:06 AM
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Default New spark plugs, now it runs like crap until FI light comes on

So, last night i installed ned spark plugs on my bike. Admittedly i got slightly wrong ones, IMR9A-9H instead of the IMR9C-9H, due to NGK's website listing the wrong one. Either way, after some searching I see this should not be an issue, at the most a very minor performance loss, but i don't think i'm worried enough to switch them back out. Here's the issue, once i got everything back together and cranked her, she would kind of sputter and wouldn't even want to idle, the RPMs were going all over from about 500-2k, then the FI light would come on and it would run like normal. Then i shut it off after it warmed up a bit to see if maybe it was a fluke, and it wouldn't even crank. It would turn over, sputter, and die. So then i waited a bit and once it cooled some, it would do the same as before: run crappy until the FI light came on. I started removing parts to try to see if maybe i accidentally pulled a fuel line out of the take or forgot a connector, but it all looked fine. I didn't even touch any of the fuel injection components, just the stuff that dealt with the spark plugs, any ideas. Also, i was wondering: i had an issue getting my socket extension to fit down into the engine until i started using a socket joint, how easily could i have damaged something inside the topend trying to get the retarded extension back out (this was only an issue for the fist one i did). I mean i didn't go hulk, but i was getting frustrated and there was no room to get it out, so i have a feeling that i might've bent something trying, i just don't know how plausible that is. Thanks in advance.
 
  #2  
Old 09-19-2011, 11:35 AM
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the aluminum threads that hold the spark plugs in are extremely easy to damage. the rule for tightening spark plugs is to tighten finger tight to make sure the threads are correct, then hand tight then a quarter turn past hand tight. make sure all the spark plug boots are on tight, if on is not on then it will running on three cylinders and it will run like crap
 
  #3  
Old 09-19-2011, 05:43 PM
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Backyard's got the call here. If you have cross-threaded the plug, you may be getting a compression leak. Never start a spark-plug anyway but by hand. By that,
I mean holding the soket and extension in your fingers, not necessarily the plug itself.
I even do a back-turn, to feel the thread's lands drop over each other, to get the
starting point.

If you have cross-threaded, don't dispair, Helicoil makes repair kits for this common issue. Goggle them if you need one.

Ern
 
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Old 09-20-2011, 09:14 AM
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Another thing to look at that people forget is the map sensor hose. It's on the left and a tiny little hose and if not plugged in your bike will run crappy
 
  #5  
Old 09-20-2011, 09:31 AM
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aw man the dreaded tune up gone wrong!

Well as these guys said if you forced a plug in and stripped the threads that could be a big issue, and costly if you need a shop to fix it.

Could you hear anything different when it was running, like compression leak?

Other than that if you removed the tank and whatnot to get to the plugs recheck everything again look for anything that you may have forgot to re hook. (wires/hoses)

also were the plugs already gapped? dunno if that would make too much of a difference.

And this is a guess as I have not done a tune up on a bike in years but how about the plugs wires - is there a firing order and you got them flipped?
 
  #6  
Old 09-20-2011, 11:06 AM
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Hey guys, thanks a lot for the help. I got a chance yesterday to take everything apart again, and i definitely did forget the map sensor hose. Running like a champ now. Thanks again! Also, what i was saying about damaging internals was when i was trying to remove the first plug i was using a straight extension and once i got the plug unscrewed i couldn't fit the extension to get it back out with that obtrusive bar that is in the way. After that i got a socket joint and smaller extension, but the first one i had to work angles and finally get it to barely slide out past that bar. I doubt i did damage anything and from what you've said it sounds like i'd be able to tell if i did. Kind of has a little flutter in the exhaust still though like a very minor miss... hard to explain. The exhaust sound just isn't completely steady. Once i get my serial to usb cable and my new map on the PC3 i'm hoping that'll make it just about perfect, if not it's not a huge issue just something i noticed. The new plugs did make it nice and smooth under 1500rpm where it would still buck a little before. Thanks again!
PS for one of my classes i'm required to write a technical instruction manual, so i should have one for spark plugs for anyone who needs it in the future, and now a good situation to add to the trouble shooting.
 
  #7  
Old 10-07-2011, 05:02 PM
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How hard is it to change the spark plugs??? on a 2005 F4i?????
 
  #8  
Old 10-07-2011, 05:05 PM
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bump, also glad to hear the OP got the bike running good. its always a simple mistaken fix...little things we forget to plug in etc...
 
  #9  
Old 10-07-2011, 09:54 PM
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Its not hard, the owners manual tells you how.
 
  #10  
Old 10-10-2011, 09:45 PM
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It's fairly easy. I actually wrote a how-to when i did it for a class i'm in. I'll see if i'm allowed to post it - don't want to get stuck with plagiarism- and do so if i can.
 

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