Plug Carbon fouling on one cylinder

[Happy Jack]

What could be causing this?.

Fuel injector, fuel pressure regulator, or ??

I’ve tried some searches with no specific luck, but the thread’s on TB cable adj and pinging were close and interesting.

My bike is a ’96 RT with 75K. Prior to leaving on a trip out West in early June, I had replaced the clutch, and performed a complete minor and major service. The 4K trip was great; we unloaded from the truck in Co., and the bike performed great also.

A couple of weeks after getting home the bike started running rough, especially at cold start up, and would start surging and loosing power once warm and crusing at 60 -65 mph. Did another carb sync, that was more difficult than any others I’ve done, and a quick check of the right spark plug, that looked a nice tan color. A couple of days ago it has gotten much worse. Cold starting requires choke and constant throttle blips until the temp gauge gets to 3 bars. Twin-max is still showing a close balance even with the engine revving up and back-firing.

I have since changed the fuel filter, fuel in the tank and checked both plugs this time. The right plug is still a nice tan color but the left plug is carbon fouled.

Thanks again for any help, your support on the clutch change-out was great.

 

Chuck

[bmwmick]

Chuck,

I'd pull the spark plug covers and the body work and run it in total darkness. Look for any arcing around the coil and the secondary wires.

Have you done a compression test? Unless the left side injector is hanging open, I doubt it's an injector problem.

 

Mick

[JonathanE]

Your fuel injection computer is only able to measure optimal residual oxygen in an average of the two cylinders, since it only has one O2 sensor in the exhaust. If one side is lean, the other has to be kept rich to compensate. The Motronic does this since it sends the same amount of fuel to each cylinder, whether or not each cylinder is getting an identical amount of air.

 

I'd look for causes of unbalance in the amount of air (and maybe fuel) between the right and left cylinders, such as inconsistant valve adjustment (left to right), one plugged injector (on the "not fouled" side), a bad TB balance, but most likely, a bad air leak on the "not fouled" side.

 

Good luck!

[T__]

Happy Jack, are you sure it is carbon fouling & not a darkening from oil fouling? When those boxer engines get some miles on them & are parked on the side stand after riding oil tends to run past the piston rings on the low (left hand side) then burn off shortly after starting next time.. My old GoldWing was bad for this & always had darker spark plugs on the L/H side..

 

Other possibilities are: a dripping fuel injector on the high carbon side (maybe try swapping injectors side to side if possible & see if the problem follows the injector move).. As mentioned above, a possible ignition or spark plug problem on the problem side (try new spark plugs or at least swapping side to side).. Low compression on the effected side (run both a cold & hot compression test).. A valve timing issue (possible but a long shot).. Valve guide wear or valve seal problems on the effected side.. Possible blockage or other dissimilar problems in the air cleaner box or intake pipe, maybe even oil or water in the air box (have you drained the air box?)..

 

Twisty

[Happy Jack]

Today I swapped sides on the fuel injectors, installed new spark plugs, attempted TBS with the Twinmax and looked for electrical arcing tonight.

Cold start running is still very rough and requires constant throttle work until 3 temp bars show. At this point the engine runs fairly well at idle and in sync. But not above, even with numerous attempts with throttle cable adjustments, even though the twinmax still shows a fairly close sync. Spraying of WD40 around the TB’s showed no changes on the RPM, but I’ll try the propane spray tomorrow that I saw on one of the threads.

A short 3 mile ride; the furthest I would attempt without thinking about pushing it back home, was rough. I could not keep the RMP from dropping with a constant throttle position, and severe surging. Due to the short ride, I could not make an assessment on the condition of the new plugs. I’m sure the old plug was carbon and not oil due to the dryness of the coating. When I cleaned the BBS of the TB’s today they too appeared to be carbon coated?

Tonight while looking for arcing, which was not seen, I noticed the first 12-16 inches, sorry I wasn’t going to get close enough for an accurate measure, of the exhaust pipes were glowing a translucent cherry red after only about 3 minutes of running! I can only guess that I have a very lean running engine.

Tomorrow I guess I’ll purchase a compression gauge, and check that.

Any other suggestions?

Chuck

[ShovelStrokeEd]

Chuck,

I'm hoping, for your sake, it is no worse than a bad iginition coil. A compression test will give you much more information.

 

Don't fret overmuch about the red exhaust pipes, that is actually pretty normal. An engine that is running excessivly lean should not produce carbon and especially not on the spark plugs so long as they are of the proper heat range.

 

A moderatly common failure here is a particle of carbon lodging on the exhaust vavle seat and preventing the exhaust valve from closing. Problem with this is the exhaust valve will quickly fail if the engine runs under load for any time. I fear you will find that the head(s) need to come off if your compression check shows low compression on the effected side.

 

The source of the carbon is most often found to be poorly seated piston rings so your problems may not end there and a new set of rings, followed by proper wear in may well be in order.

[bmwmick]

Chuck,

If you have a decent Ohmeter, next time the plastic is off, measure the primary and secondary resistance of the coil. It should be 0.5 Ohms Primary and 7.5K Ohms Secondary(if you have an early coil, it 'might' measure 13K on the secondary like mine which is an 08/1995 R1100RT)

 

You could also check the Air Temp sensor in the airbox.

Ensure the connector is seated. The resistance should be around 2.2K Ohms at 70 degrees and it should go UP as you cool it and DOWN as you heat it.

 

Mick

[Happy Jack]

First, let me update on engine mods I’ve done thru the years. 28K – Removed charcoal canister and routed an external fuel filter, 40K – Installed GS air intakes and Cat Code & 48K replaced Cat converter with a Two Brothers by-pass pipe with Ox sensor port and replaced muffler with one from a YZ. No problems with any of the items to this 75K point.

Got the compression gauge today, so wet to the shop to check some more items. Haven’t checked the coil resistance yet, hate pulling the tank, but the sparks looked good during the compression checks today.

 

1) Compression, Cold L-180 R-185. Hot L-185 R-192

2) Air temp sensor - 1.8K ohms/90 degrees, tracks hot and cold changes.

3) TPS - .330v closed throttle, 4.75v at ½ throttle and above on #1 pin

.0254v closed, 3.83 WOT on #3 pin

Noticed throttle is not slamming shut if you release throttle from WOT, coasts last 1/8”. And closed value is not constant. Weak springs &/or sticky cables?

4) Motoronic fault codes – per some info on another thread, went to the K11 site found some differences I’d like to clarify. Pin 1 had 1 wire not 2, and Pin 2 had one Brown/Blue wire not Brown/White? The readings I got were 2344 (Ox sensor shorted to ground) and 1111 (CO pot not detected with Ox sensor disconnected). Several attempts to read further codes displayed NO lights, I never did get a 4444 (No faults) indication? How long should you have fuse 5 out to reset? I did a minute or 2.

5) Fuel injectors – Swapped sides a couple of days ago, with new plugs, the right side plug is showing some discoloration at this time with only 3miles + run time for carb sync and etc since. Hard to put miles on the bike at this time since it runs so rough, but it appears the injector may be bad. It was on the left side with the bad plug when this all started.

 

Chuck

[bmwmick]

First, let me update on engine mods I’ve done thru the years. 28K – Removed charcoal canister and routed an external fuel filter, 40K – Installed GS air intakes and Cat Code & 48K replaced Cat converter with a Two Brothers by-pass pipe with Ox sensor port and replaced muffler with one from a YZ. No problems with any of the items to this 75K point.

Got the compression gauge today, so wet to the shop to check some more items. Haven’t checked the coil resistance yet, hate pulling the tank, but the sparks looked good during the compression checks today.

 

1) Compression, Cold L-180 R-185. Hot L-185 R-192

2) Air temp sensor - 1.8K ohms/90 degrees, tracks hot and cold changes.

 

Sounds like the air temp sensor is OK

 

3) TPS - .330v closed throttle, 4.75v at ½ throttle and above on #1 pin

.0254v closed, 3.83 WOT on #3 pin

 

TPS voltage is a little low, I set mine to .385

 

Noticed throttle is not slamming shut if you release throttle from WOT, coasts last 1/8”. And closed value is not constant. Weak springs &/or sticky cables?

 

You can clean the springs with carb or brake cleaner and retest. Replacing the throttle cable may help too. Mine is still like new at 50K.

 

4) Motoronic fault codes – per some info on another thread, went to the K11 site found some differences I’d like to clarify. Pin 1 had 1 wire not 2, and Pin 2 had one Brown/Blue wire not Brown/White?

 

You really can't compare wiring colors with that reference. I wrote it for a '93 K1100LT with Motronic MA 2.1 NOT your R1100RT with MA 2.2 My diagnostic connector on my R1100RT (08/95) MA 2.2 is Pin#1(Brown/Black) Pin#2 (Brown/Blue) Pin#3 (Brown/Green) What are the last 7 digits of your VIN?

 

The readings I got were 2344 (Ox sensor shorted to ground) and 1111 (CO pot not detected with Ox sensor disconnected). Several attempts to read further codes displayed NO lights, I never did get a 4444 (No faults) indication? How long should you have fuse 5 out to reset? I did a minute or 2.

 

If the faults are not corrected, it will NEVER show 4444. I suspect you DO have a failed O2 sensor. If you unplug the O2 sensor you should see that fault clear and 1111 will remain. Our Oilheads use a 4-wire O2 sensor with internal heating element. You should be able to meter the L2 sensor and find that short.

 

5) Fuel injectors – Swapped sides a couple of days ago, with new plugs, the right side plug is showing some discoloration at this time with only 3miles + run time for carb sync and etc since. Hard to put miles on the bike at this time since it runs so rough, but it appears the injector may be bad. It was on the left side with the bad plug when this all started.

 

If that injector is defective and either sticking open or leaking, it could be the cause of your fouled plug as I mentioned earlier. If you have a good Diesel shop nearby, take both injectors to them for cleaning/testing. Usually doesn't cost more than $25-$50 for cleaning.

 

Chuck

 

Mick

[Happy Jack]

Mick, thanks for the reply. I hadn’t noticed before that the Motronic article was you, it has a lot of good info. It did say that it “may” apply to all R11100. Except for the wire colors are the code’s still the same for the R1100?

Had some bad back pain today, but I did get to check the fuel flow out of the injectors and pressure regulator. Not sure what it should be but the injector spay was misty and did not seem to have much pressure, on both sides. Also, both sides of the reg dumped ~4oz of fuel just on the power up pulse.

I ordered a new throttle cable today also.

Since I do not have a cat converter, I was thinking of removing the Ox sensor and plugging the pipe. Rob Lintini wrote an article about this with and without a Co pot that showed little difference. I’ve not been able to find any info on what the Co pot is, but it seems I’ll not need one. If I do this, will I always have a 1111 fault code, or some other? I assume the 2344 will go away.

I also assume that the Ox sensor is not the cause of the one jug fouling. I’m going to try a more through job on finding a possible air leak soon.

Thanks again,

[bmwmick]

Chuck,

Yes, most of the codes are valid for MA2.2 except for the obvious ones like the coolant temp (now oil temp) or the fan test.

 

Did you read this?

 

If that injector is defective and either sticking open or leaking, it could be the cause of your fouled plug as I mentioned earlier. If you have a good Diesel shop nearby, take both injectors to them for cleaning/testing. Usually doesn't cost more than $25-$50 for cleaning.

 

Since you seem to have moved the fouling to the right side by swapping the injectors, why not get them cleaned/tested?

 

The fuel pressure should be 43psi (right out of the manual). There is no 'flow' test that I know of.

 

Depending on your VIN, you might need more than one throttle cable.

 

Yes,

Rob Lentini and I did a lot of testing together for the CCP, O2 sensor and the CO pot. If you remove the CCP and the O2 sensor, the only fault code you will see is the 1111.

 

No, the L2 sensor will not affect one cylinder.

 

Mick

[Happy Jack]

Yes I did, sorry I didn’t mention it.

I have a Diesel shop right down the road and will have them check them out. Is the 43psi out of the injector nozzle? And will the shop be able to check that?

Last seven of my Vin is 0442153. Up until now I had also thought that the crossover cable was a separate cable from the main throttle cable, but it appears that it is one with the inner cable doing a loop on the butterfly crank and then to the right side. Correct?

So what is a CO pot and how do you make or buy one? Do you think I need one?

[ShovelStrokeEd]

The 43 PSI is the distribution manifold pressure. To attain it, you have to have the entire circuit in place, including the injectors as the regulator is the last item in the circuit before the return the fuel tank. One usually places a gauge, via a tee fitting, in the line coming from the fuel filter to the distribution block/regulator. That line is rubber and accessable under the tank.

 

A word on this, you may well have 3 bar in the fuel line and still have a clogged fuel filter. Best to replace that anyway.

[bmwmick]

Yes I did, sorry I didn’t mention it.

I have a Diesel shop right down the road and will have them check them out. Is the 43psi out of the injector nozzle? And will the shop be able to check that?

No, the 43psi is on the fuel supply BEFORE the injector

Last seven of my Vin is 0442153. Up until now I had also thought that the crossover cable was a separate cable from the main throttle cable, but it appears that it is one with the inner cable doing a loop on the butterfly crank and then to the right side. Correct?

Correct, you have a 06/1996 build date and the cables were changed AFTER 07/1996

So what is a CO pot and how do you make or buy one?

The CO pot is a 20-turn precision vernier potentiometer. Item #4 here: http://tinyurl.com/kbejj and you should try it without the pot first. Keep an eye on plug color and fuel mileage. Get rid of the CCP if you haven't already Do you think I need one?

 

Mick

[Happy Jack]

Couldn’t find a local shop to clean and check the TB’s, so I soaked them in mineral spirits and flushed with carb cleaner while energizing the TB.

So, after the loss of what little hair I had, and about my 20th attempt at carb sync I pulled the plugs again. Finally got enough run time on the engine, and the right side plug in now carbon foaled. The fuel injectors were swapped at the start of this, so another one is on order.

Only one problem due to second guessing. When I pulled the original plugs, I placed them in the proper order on the work bench, and now after several weeks including ordering parts, their placement does not match what I wrote the first day. I’m going on the assumption that what I wrote the first day is correct.

If this does not work, I would assume that the right TB is bad or a distribution manifold. Correct?

[bmwmick]

Chuck,

I've never head of a shop that would check/clean your Throttle Bodies.

You moved the problem from the left side to the right side by swapping injectors. If this is true, the new injector should fix your problem, right?

I guess I'M the one getting confused now.

Mick

[Happy Jack]

Mick,

Sorry again, I should have said injectors not TB's

[Happy Jack]

Back on the road again!

Installed a new fuel injector, well almost thanks to Beemerboneyard. TB sync and road test went well.

 

Thanks to all for your support.