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  #1  
Old 04-03-2018, 09:20 PM
Lowndes Lowndes is offline
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Throttle issue on K12RS

2000 K1200RS, 45K, AF-Xied, EV-14 injectors.

Sometimes (40-50% of the time), if I roll back on the throttle even a tiny bit, then back on the throttle even a tiny bit, it will jump, just like the spark was cut on the roll-back then started again on roll-on. 2nd and 3rd gears are the worst, maybe the higher gears do it but the gearing dampens it to the point it's not noticeable.

It seems to be getting worse, but I know it's getting on my nerves worse.

Is there a fuel shutoff or spark stop programmed in on roll-back?? No backfire ever.

Otherwise, it runs really well.

Any ideas??
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  #2  
Old 04-04-2018, 06:40 AM
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Re: Throttle issue on K12RS

Have you tried a TPS reset? what if any work have you done on the bike just prior to your issue? dead battery? replace battery? remove battery?
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Old 04-04-2018, 07:28 AM
Lowndes Lowndes is offline
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Re: Throttle issue on K12RS

I did disconnect the battery several weeks back. I'll try the TPS reset. Thank you, sir!!

It may be two weeks before I can test it and report back on the results.
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Old 04-07-2018, 12:23 AM
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Re: Throttle issue on K12RS

I had a similar problem on my K 1200RS. Somewhere in the archives on this site I described the crash that I experienced because of this very problem. I always expected the cause was the throttle position sensor. The dealer could not diagnose a problem with the TPS and I traded the bike before I did you further investigation or spent $$ to replace the TPS.
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Old 04-15-2018, 09:13 AM
Lowndes Lowndes is offline
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Re: Throttle issue on K12RS

I did the TPS reset, then put about 175 miles on it yesterday. Same thing. Not every roll-back, I can't make it do it all the time, but when it does it, it will do it repeatedly. Does that make sense?? It's definitely disconcerting in a tight corner.

I don't think this is what is commonly called "surging", is it?? More of a "jump" or "bump". It reminds me of lighting an old gas oven with a match after the gas had been on a leeeetle too long; you were lucky to still have eyebrows. That's kinda what it feels like.

I have a chip coming from John Gemi, "John the Greek", I hope. Maybe that will fix it.
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Old 04-15-2018, 09:59 AM
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Re: Throttle issue on K12RS

Annoying....amongst a few other problems I had at the time that could contribute to that, most of it was traceable to intake leaks.Much worse if fueling isn't correct as in dirty injectors but them air leaks on their own do affect fueling.

Namely bowed plastic intake manifolds for me but could be cracked rubber manifolds.
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Old 04-15-2018, 11:24 AM
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Re: Throttle issue on K12RS

THANKS, Pierre and George!!

Did the search and read a bunch of posts on several threads. Could not find the post on George's crash.

Sounds like the TPS is suspect. An air leak per Pierre is a very strong possibility as the TB's were pulled a couple of months back AND it started about then. New O-rings were installed but it's easy to roll one.

I might try the GS-911 to see if anything shows up. Steep learning curve ahead on that.

But, it sounds like it can be cured.

THANKS, again.

Will post any findings.
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Old 04-15-2018, 03:32 PM
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Re: Throttle issue on K12RS

Connect GS911.Go straight to TPS adjustment where they say to wiggle the bars and see if the graph moves.Slam throttle to its stop point.Bar in the green or very close? Not the TPS.
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Old 04-15-2018, 04:46 PM
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Re: Throttle issue on K12RS

Quote:
Originally Posted by Lowndes
THANKS, Pierre and George!!

Did the search and read a bunch of posts on several threads. Could not find the post on George's crash.

Sounds like the TPS is suspect. An air leak per Pierre is a very strong possibility as the TB's were pulled a couple of months back AND it started about then. New O-rings were installed but it's easy to roll one.

I might try the GS-911 to see if anything shows up. Steep learning curve ahead on that.

But, it sounds like it can be cured.

THANKS, again.

Will post any findings.

You can only troubleshoot these kinds of problems in terms of combo of:
(1) probability of cause / priority
(2) effort / cost needed to eliminate each possible cause.

Many here have accumulated 15 years of effort by doing it on their own K1200 and helping others solve these issues.
I am quite sure many of these members will agree with me on these:

A) By far, most of these issues are caused by various intake air-leaks. These leaks appear with age of rubber components (5 to 10 years) and they all have various source around the throttle-bodies system (above and below) NOTE that the GS911 will not give any warnings / faults for this unless the Motronic has to compensate to the maximum allowed in the algo (to make mixture richer).

B) The next most probable cause with age has been the wear of the spark-plug wires. This will cause various arcing spots hidden from view (under plastic cover). Can often be seen in dark with engine running and a light mist sprayed over the plug wires.

C) As mentioned earlier by Pierre (Pbegin) the next most probable spot has been the blockage / imbalance of injectors. This is just normal on any modern fuel-injection vehicle with age. This will rarely cause catastrophic failure but may cause annoying imbalance fueling symptoms. Still.... less common than the above 2 others cause.

D) With these K1200 getting close to 17 years old (on average), we have also seen an increase numbers of low fuel-pressure problems. In some case the fuel-filter should have been change a long time ago. IN OTHER CASES, the fuel-pump was just at the end of its lifetime. We have a few threads here how to check proper fuel-pressure with a tool that will not cost more than $US$ 70 (and will also serve on many cars).


Until these items have been checked / eliminated, anything else is just a loss of time and money. OF COURSE, we have to assume the bike tune-up is up-to-date including fuel-filter and valve adjustments.

A GS911 fault readout is a very good start to give some direction - however some faults (air-leak, low fuel pressure) will not give any fault codes on these older/simple Motronic ECU. Newer models ECU after 2005 are a lot smarter, more sensors and have a lot more diagnostic codes (R1200 boxer, K1200S, K1300S, K1300GT, K1600, S1000R...).


FINALLY...
A chip change is wishful thinking... unless you have a 166 chip and the problem is ONLY during cold start. For any other issue, a newer chip / ECU might cause minor improvements BUT will not solve the real issue causing these symptoms.

P.S.: to simplify the troubleshooting , you should remove the AF-Xied for a while. It is only masking the real issue(s) and will make troubleshooting more complicated. When / If you have a fairly good running K1200RS engine, then you can plug it back and see if it really runs better. It may and it may NOT... but mine and many others do not need any of this IN STOCK CONFIGURATION.
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Old 04-15-2018, 05:10 PM
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Re: Throttle issue on K12RS

Not sure about the older ones but my '02 did that and the dealer fixed it with an update
to the ECU.

If we had access to the pre '05 archives we could find it.
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Old 04-15-2018, 11:31 PM
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Re: Throttle issue on K12RS

I was going to suggest the spark plug wires, but saw sailer suggesting those already.
Maybe pull the cover off to expose the wires and see if anything is arching while the bike is running and if not just for the sake of it, I'd spray the wires with a little water from a spray bottle and see if the bike starts to miss.
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Old 04-16-2018, 08:25 AM
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Re: Throttle issue on K12RS

THANKS, Sailor,

The plugs and wires are new OEM type (<1K miles).

The injectors were recently replaced with EV14 units, just after the plug wires.

The PO said the bike was "completely tuned up" by the dealer, including all the fluids and valves at about 40K (46K now). NOT sure if the ECU has been updated. Would the GS911 indicate that??

Cold (and hot) starts are no problem. PLENTY of power and runs really smooth (until it hits the rev limiter!!). 33-35 mpg is the norm. It's just the let-up/roll-on BUMP that is the issue. It SURE feels like ALL cyls are not firing then START firing at the same time. That's what tells me it's either spark, fuel, or both, and that would be the ECU, or, something (O2, TPS, etc) sending bad info to the ECU. Doesn't seem like a fuel starvation by clogged filters because it runs really well at heavy throttle/high-flow for longish periods with no issue.

Not positive if this happens at a let-up to Zero throttle, or just a slight/partial let-up. If it's only a Zero throttle issue, that points to the TPS or ECU map, correct??

It would seem to me that an air leak would be causing this issue 100% of the time, not the 40-50%, and it would affect only one cyl.

When the TB's come off to check the O-rings and plastic collars, I'll clean the inside of the TPS with contact cleaner.

It's easy to disconnect the AF-Xied and eliminate that influence. Will do.

Are there any ports on these TB's for vacuum tubes to connect to, like on the R bikes?? THAT would be a big help. I don't recall seeing any. The Harmonizer would point out any air leaks very quickly, even at low or no throttle.

Thanks, ALL for the accumulated wisdom here!!
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Old 04-16-2018, 09:46 AM
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Re: Throttle issue on K12RS

Quote:
Originally Posted by Lowndes
THANKS, Sailor,

The plugs and wires are new OEM type (<1K miles).

The injectors were recently replaced with EV14 units, just after the plug wires.

The PO said the bike was "completely tuned up" by the dealer, including all the fluids and valves at about 40K (46K now). NOT sure if the ECU has been updated. Would the GS911 indicate that??

Cold (and hot) starts are no problem. PLENTY of power and runs really smooth (until it hits the rev limiter!!). 33-35 mpg is the norm. It's just the let-up/roll-on BUMP that is the issue. It SURE feels like ALL cyls are not firing then START firing at the same time. That's what tells me it's either spark, fuel, or both, and that would be the ECU, or, something (O2, TPS, etc) sending bad info to the ECU. Doesn't seem like a fuel starvation by clogged filters because it runs really well at heavy throttle/high-flow for longish periods with no issue.

Not positive if this happens at a let-up to Zero throttle, or just a slight/partial let-up. If it's only a Zero throttle issue, that points to the TPS or ECU map, correct??

It would seem to me that an air leak would be causing this issue 100% of the time, not the 40-50%, and it would affect only one cyl.

When the TB's come off to check the O-rings and plastic collars, I'll clean the inside of the TPS with contact cleaner.

It's easy to disconnect the AF-Xied and eliminate that influence. Will do.

Are there any ports on these TB's for vacuum tubes to connect to, like on the R bikes?? THAT would be a big help. I don't recall seeing any. The Harmonizer would point out any air leaks very quickly, even at low or no throttle.

Thanks, ALL for the accumulated wisdom here!!

Thanks for detailed reply.
Unfortunately, you are assuming way too much... When troubleshooting these kind of problems, each item has to be confirmed and eliminated with 100% accuracy (or as close as possible without opening the engine completely - unless required).

The fact that a part was replaced or you were told a dealer did a particular job means little to me..... in my experience these are often the area to backtrack for the source of the problem.

Let me give you 3 "real" examples that applies to current situation:

(1) One very good mechanic I know had done a full clutch job on a K1200LT. After the job the engine was missing intermittently at certain RPM range only (like if it was running on 2 or 3 cylinders instead of 4)

It took him a long time to eventually find out that one of the 4 injectors connector was not fully seated. Not visually apparent and the contact was good enough that engine ran OK most of the time. So.... having new injectors is just one more source of "potential" issue....

(2) A fairly competent home mechanic had replaced all 4 spark-plugs, but assumed all 4 spark-plug caps were fully seated - "they sure looked and feeled OK to me" he said. You can guess the rest of the story ;-)

(3) A fairly competent home mechanic had bough a used K1200RS. Under previous owner a full clutch job was done at his BMW dealer. So he obviously used this as a so-called "competent" repair job when selling it.

Well... it took a few rides in various temp (of course, not fully tested when buying) to find out something was not right when engine was very cold or very warm. The engine coolant sensor wire was damaged (quite possibly when engine was lowered during clutch job).

Motronic ECU has a default value of 80 celcius (176 F) when it sees implausible value from this sensor. Of course, engine will run OK when a bit warm (but not at extreme end of the temps)

CONCLUSION:
Only the last item was helped by a GS911 readout of faults. Because these BOSCH Motronic ECU are pretty simple EFI systems (compare to more recent ones), they will not give any clues about the other 2 problems: these needed some backtracking and detective work. A good detective does NOT assume anything ;-)
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Old 04-16-2018, 10:30 AM
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Re: Throttle issue on K12RS

Sailor,

Agreed on all your points. "Assume nothing!" is the standard. Even your own work when diagnosing an issue (especially mine).

I personally did the plugs, wires (twice - bad wire on the first install), injectors (very involved process with mods for new style injectors, much trial, and re-do).

I've experienced clogged fuel filters, bad wires, bad plugs, bad fuel, valves not right, etc, etc. on numerous bikes and cars, trucks and know the symptoms fairly well. I've experienced a ride home on 3 cyls on this bike and "this ain't it".

This issue is a momentary "on-off-on" on all cyls at the same instant. At all other times, the engine is running very well. That's what tells me ECU (or something feeding the ECU) cutting the spark and fuel to all cyls at the same instant with the same input conditions (ro-ro), no backfire or blueing.

I do appreciate your input and analysis. I enjoy the skull session and wrenching almost as much as riding!!
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Old 04-16-2018, 10:31 AM
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Re: Throttle issue on K12RS

Yes there are vacuum ports.On your bike connected to the "air valve" and charcoal canister if still there?There is a potential for leaks in that area.

And yes a vacuum balancer could give you clues as to vacuum leaks.I successfully balanced my TBs with my old mercury column manometer but only after addressing the leaks.Not for the squeamish or impatient home tech balancing them TBs.

Depending on milleage accumulated since the recent work or/and riding conditions most if not all them leaks will show as oily looking seeps/blowback around the affected area.4-5000 miles of dirty dusty roads will do it?

TPS cleaning?I don't think you can inject cleaners inside the sealed TPS. But the potentiometer tracks can be checked in place.Easier with a spare connector ripped out of another harness but with the right small female connectors one can fabricate leads to connect the meter and check the tracks.

Yes fuel pressure....my DIY gauge was cheap.Has old QDs on it so takes 5 minutes max to connect even with the plastics on.Pressure and pressure bleed down over time (1/2- 1hr) is SOP for me anytime I change filter or do anything related to fuel supply.Had to go back in the tank once to re-tighten a line.Pressure was dropping over 1/2 hr.

I even made another FP gauge the other day.Hardware(tee and barbed connectors) was less than $10.00 but I already had a good gauge.So $20.00 total if one has to buy a liquid filled gauge for about $10.00?I'd have to connect that one with a hose at the rail but I made it for other FI vehicles.Tested on a Subaru....!

Last time I checked my bike...25PSI residual pressure after 2 days.

I also had a defective FPR.Down by about 4 PSI.Stole one from a 1200GS to keep riding but installed the defective one back into the GS.Same lower readings and accelerating from 2-3000rpms I could feel the slight sputters.

New injectors? I contaminated a freshly cleaned set rather quickly from not cleaning my fuel lines/rail before I installed them.What I really should have done was to cut the fuel filter right then.I would have noticed the dirt on the outlet side and cleaned my fuel lines/rail.Too much fuel injector cleaner?May have dissolved the dirt into particles small enough to go through the filter and then re-contaminate my injectors?

2 12oz bottles of Techron.That's all I used over 25,000 miles last summer and I'd say quite a few iffy looking fuel pumps in remote areas with regular gas only.Injectors pass the injector pulser balance test with for now flying Kolors.
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Old 04-16-2018, 03:45 PM
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Re: Throttle issue on K12RS

Pierre,

Thanks for the info on the ports. I still have the carbon can installed, am considering removing it.

NO dusty roads for me. This ain't no dirt bike!! I did a good cleanup on the oil lake on top of the motor before and after the breather replacement.

I think it was Dennis Andress that described cleaning the TPS in another post on this forum. He indicated it fixed his similar problem.

I had the injectors off and on many times getting it right. I did the EV14's (4 hole) on my R11S a while back and wanted to do the same with this K bike. This may be the only EV14 install on a K, have not seen it anywhere. It "took some doin"". The tiny screens on the inlet side of the injectors were always clean - I checked them worried that junk would get dislodged during all that. I've run the Techron thru it, too, per Dirt Rider.

I spray tested them on my R bike before installing on the K, also.

So far, the only thing that would start and stop the fuel (injectors) and spark instantly and on all 4 cyls and in a very small, confined parameter would be the ECU (or one of it's sensors).

Am I missing something??
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