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Discussion Starter #1 (Edited)
Hey All,

I have a 2006 Tiger 955i, 64,000 miles, having some running issues. Ready to dive into a quagmire (kind of, I mean there are a lot of details here)?

These are intermittent, although they seem to have become worse over time. I bought the bike last fall and have run a few tanks of gas through it, the running has changed a bit over that time.

Probably unrelated to this issue but in the interest of full disclosure: I was told when I bought it that when turning on the driving lights and heated grips, that "it did funny things electrically" so the previous owner didn't run those. I figured all of this issue may be a charging issue. I tested regulator and it didn't pass, and voltage was all over the board. New regulator and it is rock stead voltage as it should be. So I assume that that is taken care of. It does have an aftermarket regulator hung on the side, wired directly to the battery, the normal regulator mod. I've cleaned connections and they are tight, but not quite new and shiny as could be. Very probably ok; they had some oil on them which I brakleened off pretty well, squeezed female blade connectors to tighten, etc.

I've tried a few things to fix the running issue but don't have some tools so have been limited.

No check engine light.*

I've noticed two main conditions, though they may not be related: Rough idle just after startup when cold, and sometimes won't rev all the way to redline.

The detailed symptoms:

The idle condition is worse when cold for sure. Colder it is (have tried it from 20F, up to 55F), proportionally worse the condition has been.
Starts up and revs to about 1500 RPM just fine...for about 5 seconds. Sometimes this has been as long as maybe 20 seconds. It seems it used to take longer to idle poorly but since I've been messing with it
It seems to have a high idle programmed for cold startup, then settles down into its normal idle? As soon as it settles into normal idle the tach pretty much has continued to drop off into the mid-hundreds range and gargles all over, needs a little throttle to stay running. Once warmed up it usually has idled fine.

My initial rides after purchase, it revved up to redline sometimes just fine, but at least once it was a thousand or two shy of redline and wouldn't climb any further. The total refusal to go all the way to redline was rare, and I haven't seen it do that for a while. Though a few times it has seemed reluctant to rev hard.

Also, cutting throttle most anytime it has that little lurch as if the engine didn't run for a moment (it does run), the classic lean condition if I'm not mistaken (a trait from tuning carbs) although never any crackle on overrun or anything.

Used to pull hard right off of idle when leaving stops. Like almost no throttle needed, I loved this trait when I bought it. Now it gargles and needs additional clutch slippage to be sure, and when rolling on throttle has a little gargle before it can handle it. I can't tell if it is missing in one cylinder or affects all three. At times I've thought for sure it sounded like one cylinder not working well, others seemed a general burble/poor running.

So...initially I liked the idea maybe it was dirty injectors, fuel fliter, or something. Have run copious amounts of SeaFoam through it, let it sit for months with it in there, and previous owner did say he tried injector cleaner also.

Obviously first thing I tried was fuel filter.
Then (kinda liked the idea of having a spare pump with the bike) tried a $12 ebay fuel filter just to see if that did it.

The fuel pressure regulator in this bike is totally different than the others I've seen on forums or even parts fiche for this bike. I found one on a 2005 Speed Four parts fiche. It is mounted totally internally. It mounts to the pump bracket thing by one 8mm bolt, and has like a 10mm hole in it which I presume is where the excess fuel bleeds back into the tank. It had a nice little tin cap with a spring inside which was almost totally compressed from new, and I tried to "tune" it by tapping it down a little (no change in running), then tapping it down quite a bit, then clamping it in a vise to totally compress the spring and threaded a bolt into that exit hole to totally plug the thing off and see if that made a difference. I had wondered if the valve seated squarely and/or the seal in there was corroded by ethanol or something. My guess is that it has too much pressure right now, I don't have a pressure tester handy and/or one which connects to the quick disconnect to test it. **Can it have too much pressure? It has basically run the same as I tired to crimp this thing incrimentally, It could be the reason for the poor off-idle performance when leaving stop signs, and for all I know it also could've helped it rev to redline, as it seems to (maybe) have worse off-idle now and better higher end pull (but this is not fact...these conditions have varied a bit from time to time even within a few minutes of riding or from revving out one gear to the next, it isn't an exact observation). Should this pressure regulator be replaced? Should I not think about this issue until after testing fuel pressure? I may have found one on a parts fiche that matched mine, probably $65, not something I care to try unless it needs it.

So...moving onto injectors. Tried to buy the only ones on ebay which fit this (the longer type) and they're held up in shipping right now. I don't like "throwing parts" at something, but sometimes for the price of a cheap fuel pump and used injectors, as these things can be tricky to test also, can be easier than testing things. I did pull the injector rail and watched each one and they seemed to look pretty much equal to me while cranking. Not a great test to guarantee they're alright, but if one was odd then it would indicate an issue. Also counted pulses while filling a small vile, and all 3 seemed to fill to the same place on the vile with 20 pulses. Not an exact scientific measurement, but they looked the same to me.

I also tried to pull injectors one at a time and isolate the offending cylinders, running it on one or two at a time to see if one was weak. At times it seemed for certain that one cylinder was weak, but then repeated the round of testing and was totally uncertain. The issues are somewhat intermittent; always there to a degree, but not always consistent.

I didn't have a thin walled plug socket right away, but after I dug my grinder out of a snow bank this spring I clearanced my 18mm and plugs 1 and 2 were nice dark tan (a little darker than most would call ideal (I understand a modern FI engine should be almost white)) but number 3 was downright blackened (though only the tip of the insulator, not up into the threaded metal part. Yes, I know it could in theory be a bad plug at this point...but it seems that would be caused by something, and if it isn't fouled up into the insulator isn't it fine for these purposes? I know...start with the basics, but its a nice iridium $10 plug, I sanded the gap a little, that's shiny, and I'm pretty sure the issue is worse than would be caused by one plug like that, and it runs fine for 5 seconds after startup, so I'm not sure. I did install that plug into a different cylinder but have only ridden it once since, haven't had it apart to see if that issue moved to that cylinder or what. Obviously pulling injector wires wouldn't foul a plug.

So I thought it was worth some new used coils.

Airbox/MAP sensor: I know I should've tried this right away but I have not cleaned that sensor on the front right side of the airbox. Is that intake temp or MAP. I assumed it was intake air temp. Does it use a MAP 5 seconds after startup (if it has a map sensor)? Would that cause it to not rev out (if the same issue causes both symptoms)?

IAC valve: I watched that and it ran through they cycle just as the videos on Youtube indicate. Also, figured that wasn't it because of the not revving out issue. I did look over the 3 hoses from that to the throttle bodies and they all looked to be in great shape visually. Again, even after it needs some throttle to stay running it hasn't run perfectly with that little throttle help. It is as if something else is at play.

Airbox was opened up quite a bit when I bought it. I think it had 2 snorkels from the front sides? it has 2 gaping holes in that part. The thing is wide open, but I presume it ran fine after that mod.

The little gasket that goes around the AIC was a piece of tubing that was sliced lengthwise and didn't fit in there very well, but I think that is not an issue. The last time I installed the air box I left that out.

Kill Switch: On occasion when I turned the key on nothing happened. I flicked the kill switch a few times an it all came right on. I suspect some terminals in there are not making contact, but I doubt(?) this is the issue.

Codes: I obviously had codes when pulling injector plugs. But that is it, cleared them and went away. I did flick that kill switch a bunch of times with ignition on (have usually had it off) and it did throw fuel pump relay and pump codes, but I think it was confused by the flicking. Could this be an intermittent fuel pump relay like temporarily cutting power to the pump? I am seriously doubting that but I don't know.

I've looked over wires, tried to wiggle things while running (though everything is pretty well packed in there under air box, looked for hoses or whatever might be amiss...checked grounds... Haven't run with the fuel cap off to see if its vacuum locking, but the issue is consistent and not really that sort of thing (could it do that within 5 seconds after startup(? I doubt it but I have forgotten to try opening the cap to check).

TPS: I doubt it is the TPS but I guess could be anything. If I correctly read the normal scan tool I used, it read a 11.4 throttle closed and 90.2 wide open, and a few stops in the middle were predictable 23 and 50 or something. I couldn't read the readout in real time, it took snapshots. But its rolled fine through the range for what that's worth. Could it be thinking its wrong at closed throttle and also WOT? Given the other symptoms I haven't focused on the TPS.

Synopsis: My first thought goes to that fuel pressure regulator...but it has had the same issues throughout, unless too little pressure and too much pressure have similar symptoms...(though I wouldn't be surprised if I caused this off-idle leaving a stop issue and the fouled plug by crimping that thing off). Is this a serious issue, too much pressure? I can buy a new one or make a pressure test happen if it is that critical. If the increased pressure caused only one plug to foul then that might lead me to believe that that injector is an issue. Again, I have on order the only 3 used injectors I could find for this bike and they are held up in shipping right now.

I also think the injectors may be an issue, although that may or may not be the reason for a somewhat-fouled plug.

Always the wild card ECU, or wiring I haven't wiggled because it's buried under the air box. I haven't tested compression FWIW.

I'm probably missing something I'm describing here...but that's the most of it. I could do some more legwork chasing around that fouled plug, swapping injectors and whatnot to see if something follows it...but am ready to ask if anyone reads this and its an obvious solution to them rather than me taking that tank off one more time :)

Thanks for reading!

2,298 Posts
Hi :),

Wow.....that was some first post, lol !! Great to see someone who knows what they're doing mechanically with a motorcycle, and it seems you've covered most of the things we would recommend you doing already ;)

I would have gone for fuel flow, injectors, IACV + hoses, electrical ??

Have you thought about putting a new map on it, and in particular the TOR map. The TOR map tends to iron out many of the Tiger running "quirks" ?? I think I would do that, see how it performs, if it's still crap investigate further :unsure:

4 Posts
Discussion Starter #3 (Edited)
Thanks for the response! I laughed to myself that at one point there were like 85 views yet nobody dared respond.

Yes, I know I posted an entire thread in the first post...because yes, I know the basics but posted because running out of options.

I plan to visit my local dealer today to see if he has a way to test fuel pressure, that is the next thing and/or I will probably order a new fuel pressure regulator just to be sure, since that one is, uh, "disabled" at this point. As noted, I have ordered the only set of injectors I've found for sale, but the mail is shut down and they're sitting in a warehouse somewhere. (Actually a new listing just popped up on ebay for my longer style injectors, but its from Germany and 4X the price of the others. I can look this site over for some for sale, or maybe someone has a long "F-type" injector they'd sell me or lend me for diagnostics?) Its tough to invest in diagnosis when I haven't eliminated the basics.

And no, I haven't tried any new maps. I'm thinking it is more serious than a "quirk", but I could try that I suppose. Thanks for your attention and the tips!

4 Posts
Discussion Starter #4

I think a new fuel pressure regulator has fixed it.*
I will certainly say +1 on all of the forums I have read to focus on the FPR on these 955i's before looking too hard at anything else. This may be a maintenance part, worth replacing every so often (this '06 has 64k on the clock).

The bike really acted up in very cold weather and I haven't tried it that way yet, so there is always some guessing here.
But installed FPR and it immediately ran almost perfectly. When it used to idle all rough a few seconds after startup, it ran great with new FPR. Revved out very nicely (which it hadn't sometimes). Pulled hard right off idle leaving stop signs.

Refresher: I had tried the "adjustment" of the FPR by denting in the top to tighten the spring as many forums suggest. Tried that in 3 increments, until finally I totally crimped it shut and also plugged off the bleeder line so there was no way for it to bleed at all, effectively eliminating the FPR. None of these things worked, and it ran very poorly when plugged off. It had similar conditions before crimping it and also after, which is interesting (both at low and too high pressures). Technically I did replace the O-ring at same time, so in theory it could've been only an O-ring issue, but I don't think so because it had latent pressure when removing fuel line, and also the old one looked alright, was snug fit, and the final crimp made it run worse indicating that it had too much pressure (and ring was sealing). Only being technical, as changing more than one variable at a time can always leave a bit of doubt. But I did start it up and it ran poorly as normal at that temperature, then changed it and it ran better, then tried it again next morning when cold again and it ran great.

Great*: It still has a little "hunting idle" (it is called). Sometimes ran perfect, idled perfectly. But on occasion it idled at 1100 or so, then slowly drop to 500 (taking 3 seconds to do so), then slowly rise to 1100 again (taking 3 seconds to do so), and repeat. Very much as if the IAC was slow to react. So plan to clean that out and work on the fine tuning, but this was an intermittent condition and overall the bike ran great.

My theory is that it had two conditions: The primary one being the FPR and that exacerbated by the IAC acting intermittently. So it ran kind of o.k. sometimes, then very poor (not idling when cold) at other times. Making testing quite challenging. Lesson: May be worth prioritizing obtaining a fuel pressure tester right away, not inferring how it runs based on the crimping of the regulator. I suspect that the regulator issue was the gasket in there being corroded and not sealing properly (intermittently sealing well), not the spring tension being inadequate (or both).

Thanks for your feedback and suggestions. Maybe this one will be on the record for someone else to learn from(!).
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