BMW K bikes (Bricks)

You are not connected. Please login or register

View previous topic View next topic Go down  Message [Page 1 of 1]


1Back to top Go down   Rough Idle and Missfire when warm Empty Rough Idle and Missfire when warm on Wed Sep 25, 2019 11:37 am

fizcris

fizcris
active member
active member
Hi Guys,

Could you please help me to troubleshoot the following issue.

The bike rides well generally but it has a very rough IDLE, it is not stable as shown in the video below, specially when it warms up. Also when it is very warm, it drives awfully, it missfires a lot and it seems like it has got no torque at low revs at all. In city enviroments I need to rev it more than 3k rpms to avoid stalling and then release the clutch. 





I have done the following that greatly improoved the bike performance but left me still with the issues named before: 

  • Compression test (All cylinders more than 11bar) Great cheers
  • Valve clearance check and adjustment - All seems correct
  • Change Spark plugs (No lean condition, a bit of soot even on the old ones)
  • Injection syncronization
  • "Z" shaped tube change
  • Check for vacum leaks - No change in IDLE


To Do:

  • Change temperature sensor. (I don´t think this is the right thing to do as the engine runs fine when cold and the fan has been working fine), I am aware that it is a dual sensor though)
  • Change fuel filter
  • Keep troubleshooting


Has any of you had similar issues and could point me in the right direction?


Cheers



Last edited by fizcris on Wed Sep 25, 2019 12:29 pm; edited 1 time in total

    

2Back to top Go down   Rough Idle and Missfire when warm Empty Re: Rough Idle and Missfire when warm on Wed Sep 25, 2019 12:23 pm

duck

duck
Life time member
Life time member
My first guess would be coils.

Lots of good troubleshooting here: http://www.kforum-tech.com/electrical/EFI/bike-wont-start-EN.htm


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
http://www.ClassicKBikes.com
    

3Back to top Go down   Rough Idle and Missfire when warm Empty Re: Rough Idle and Missfire when warm on Wed Sep 25, 2019 1:54 pm

moriarti

moriarti
Silver member
Silver member
Hi my friend,my first thought is to change/test HT leads and sparkplug caps as well as coils
good luck.you dont say if the engine ran ok at any time before.


__________________________________________________
1984 k100 rs red/black VIN  0004449
    

4Back to top Go down   Rough Idle and Missfire when warm Empty Re: Rough Idle and Missfire when warm on Wed Sep 25, 2019 2:09 pm

fizcris

fizcris
active member
active member
Hi Guys,

Thank you for the answers, I will start testing the coils and leads for issues. I will keep you up to date with the answers.

The bike actually runs fine when cold, and it does not have any lack of power/missfire after 2.5k revs.

Regards.

    

5Back to top Go down   Rough Idle and Missfire when warm Empty Re: Rough Idle and Missfire when warm on Wed Sep 25, 2019 2:37 pm

Arlina

Arlina
Life time member
Life time member
Sounds like the temp sensor, have been there before.
Replace the bugger.
1 lead of the sensor is the fan, hardly breaks.
The other is for the EFI, how many fuel it has to give. There it goes wrong.


__________________________________________________
Rough Idle and Missfire when warm Eu-log10  K1100RS/LT - R1200RT - R1100RS (RIP) - Cagiva SST 350 Ala Verde
    

6Back to top Go down   Rough Idle and Missfire when warm Empty Re: Rough Idle and Missfire when warm on Wed Sep 25, 2019 2:42 pm

duck

duck
Life time member
Life time member
@fizcris wrote:Hi Guys,

Thank you for the answers, I will start testing the coils and leads for issues. I will keep you up to date with the answers.

The bike actually runs fine when cold, and it does not have any lack of power/missfire after 2.5k revs.

Regards.

I had a local guy come by with similar symptoms.  Swapped in other coils and issue went away.  That's why my first guess above was coils.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
http://www.ClassicKBikes.com
    

7Back to top Go down   Rough Idle and Missfire when warm Empty Re: Rough Idle and Missfire when warm on Wed Sep 25, 2019 5:25 pm

charlie99

charlie99
VIP
VIP
yep threw 6 coils away last year  all measuring open circuit , im sure they worked ...to some degree, but not good enough

most of the older greyish original coils I have measured were very close to 10,000 ohms (10k) and work well if leads , plugs (inc thimbles ) and plug tops are kept in good order.


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%ORough Idle and Missfire when warm Au-log10

"redframe" rs "bitsa"  with many contributions from the k100 community ,,with many thanks
    

8Back to top Go down   Rough Idle and Missfire when warm Empty Re: Rough Idle and Missfire when warm on Wed Sep 25, 2019 6:32 pm

chris846

chris846
Life time member
Life time member
"Replace the bugger"


Hi Arlina, impressed. Is that just a great ability in English, or is bugger a Dutch word too?


__________________________________________________
The Longest Lunch
    

9Back to top Go down   Rough Idle and Missfire when warm Empty Re: Rough Idle and Missfire when warm on Wed Sep 25, 2019 6:55 pm

Woodie

Woodie
Life time member
Life time member
I think it's time for me to replace the 'bugger' too in the K100.  Do you have to drop the coolant to do this or can the swap be done without this added bit of work?


__________________________________________________
1985 K100RT
52667
"Keep your stick on the ice.  We're all in this together."  Red Green
    

10Back to top Go down   Rough Idle and Missfire when warm Empty Re: Rough Idle and Missfire when warm on Wed Sep 25, 2019 7:10 pm

MartinW

MartinW
Life time member
Life time member
It can be done without dropping the coolant with a proviso that that surface and threads are clean. Once you are able to access the sensor you can do a quick swap and loose a little coolant. You can also make up a rubber bung and do it at a more leisurely pace and probably loose roughly the same amount. Top up the small amount of coolant that you have lost after cycling the coolant. Do not use thread tape or sealant on the threads of the sensor it will cause problems with the sensor obtaining a good earth. If the threads are fouled or corroded you will have to drop the coolant in order to clean.
Regards Martin.


__________________________________________________
K75s Hybrid
    

11Back to top Go down   Rough Idle and Missfire when warm Empty Re: Rough Idle and Missfire when warm on Wed Sep 25, 2019 9:16 pm

Woodie

Woodie
Life time member
Life time member
The answer I was hoping for Martin, thank you.


__________________________________________________
1985 K100RT
52667
"Keep your stick on the ice.  We're all in this together."  Red Green
    

12Back to top Go down   Rough Idle and Missfire when warm Empty Re: Rough Idle and Missfire when warm on Thu Sep 26, 2019 12:05 am

MartinW

MartinW
Life time member
Life time member
When I did mine I either used my thumb or finger to block the hole until I positioned the new one. Don't have the radiator cap removed when you do it, otherwise the coolant with gush out. 
Regards Martin.


__________________________________________________
K75s Hybrid
    

13Back to top Go down   Rough Idle and Missfire when warm Empty Re: Rough Idle and Missfire when warm on Thu Sep 26, 2019 5:01 am

charlie99

charlie99
VIP
VIP
@MartinW wrote:When I did mine I either used my thumb or finger to block the hole until I positioned the new one. Don't have the radiator cap removed when you do it, otherwise the coolant with gush out. 
Regards Martin.

yep ...all the above

usually always the threaded section on the temp sensor is corroded , requiring cleaning

don't know if copper slip when reinstalling could be a good idea ...but makes sense that it could help

good luck


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%ORough Idle and Missfire when warm Au-log10

"redframe" rs "bitsa"  with many contributions from the k100 community ,,with many thanks
    

14Back to top Go down   Rough Idle and Missfire when warm Empty Re: Rough Idle and Missfire when warm on Thu Sep 26, 2019 9:55 am

moriarti

moriarti
Silver member
Silver member
Copperslip is ok (clue is in the name) 
remember a little goes a long way.Just a smidgen is more than enough. Rough Idle and Missfire when warm 112350


__________________________________________________
1984 k100 rs red/black VIN  0004449
    

15Back to top Go down   Rough Idle and Missfire when warm Empty Re: Rough Idle and Missfire when warm on Sat Oct 05, 2019 6:55 pm

fizcris

fizcris
active member
active member
Hi guys,

Thank you for your answers, here is some updates to the troubleshooting process:

I have replaced the temperature sensor as per recommended.  The circuit was very rusty, I just had time to do one cleaning cycle with distilled water. I am trying to get some chemical rust cleaner to give it another couple of cycles to eradicate completely the rust from the system but it's getting a difficult task to get some of these cleaners here in Spain...

By the way, I have been using some Copper Slip to screw the sensor in and it looks like an amazing grease to have in your workshop for electrical stuff. Thank you for the tip cheers


Here is a video of the bike  with the engine cold on idle after the sensor change:




I have to say that the bike runs way smoother in every situation with completely stable idle when cold. It was running too rich before, now it's more like it´s got the right fuel/air ratio for any engine load and rpm ranges. 

Unfortunately, all the issues did not go away with just a sensor swap (that would be too easy... Rolling Eyes ), when it warms up a slightly unstable idle appear as per shown in the video below:



One really odd thing happens. When I press the starter button with the engine running and have no gear engaged no change in rpm happens. But, if any gear is engaged and the clutch is pressed and then we test the mixture with the starter button again, the idle rpm lowers about 100-200 rpms... affraid


I have been thinking about this and my first try was to check the spark plug leads, they were a bit corroded so I clean them a bit and put some Copper Slip on them. That didn't make any improvements, I even checked unplugging and moving all the spark plug caps one by one but I don't think there are any out-of-cylinder sparks happening.


So I need some advice here, my next step will be to replace the whole electrical ignition system : coils, HT "Realm" leads and Hall sensor. Or do you think I should be focussing more on the fuel injectors and fuel line?

Regards.

    

16Back to top Go down   Rough Idle and Missfire when warm Empty Re: Rough Idle and Missfire when warm on Sat Oct 05, 2019 8:08 pm

Laitch

Laitch
Life time member
Life time member
@fizcris wrote:. . .my next step will be to replace the whole electrical ignition system : coils, HT "Realm" leads and Hall sensor. Or do you think I should be focussing more on the fuel injectors and fuel line?
Back on September 25 you indicated you were going to replace the fuel filter? Have you replaced it, or inspected it? Is the interior of the tank clean, are the hoses inside the tank 30R10 type, in good condition and connected well?



Last edited by Laitch on Sat Oct 05, 2019 9:02 pm; edited 1 time in total


__________________________________________________
1995 K75 73,000 miles
Rough Idle and Missfire when warm Usa-lo10
    

17Back to top Go down   Rough Idle and Missfire when warm Empty Re: Rough Idle and Missfire when warm on Sat Oct 05, 2019 8:56 pm

Point-Seven-five

Point-Seven-five
Life time member
Life time member
Distilled white vinegar is a very food cooling system cleaner.  Get a gallon (4 liter jug) and fill the system.  Run the engine to warm it up and let it sit over night.  Drain and flush with distilled water before refilling with antifreeze.


__________________________________________________
Present:
1994 K75RT
1991 K100RS
1988 K100RS SE

Past:
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

18Back to top Go down   Rough Idle and Missfire when warm Empty Re: Rough Idle and Missfire when warm on Sun Oct 06, 2019 8:07 am

Poupy

Poupy
active member
active member
@fizcris wrote:Hi Guys,

Could you please help me to troubleshoot the following issue.

The bike rides well generally but it has a very rough IDLE, it is not stable as shown in the video below, specially when it warms up. Also when it is very warm, it drives awfully, it missfires a lot and it seems like it has got no torque at low revs at all. In city enviroments I need to rev it more than 3k rpms to avoid stalling and then release the clutch. 

I have done the following that greatly improoved the bike performance but left me still with the issues named before: 

  • Compression test (All cylinders more than 11bar) Great cheers
  • Valve clearance check and adjustment - All seems correct
  • Change Spark plugs (No lean condition, a bit of soot even on the old ones)
  • Injection syncronization
  • "Z" shaped tube change
  • Check for vacum leaks - No change in IDLE

Which make/ref of spark plugs did you install?
Are the HT wires original?
How did you achieve your synchronisation? It is not because the depressions are equal in all circuits that the synchro is good. It is important to check that when you tell the injection brain that the throttles are closed (the famous clic when turning the gas handle) the throttles are effectively closed. Otherwise the calculator makes wrong gas mixtures calculations, which can lead to the problems you mention.

    

19Back to top Go down   Rough Idle and Missfire when warm Empty Re: Rough Idle and Missfire when warm on Mon Oct 07, 2019 8:47 am

fizcris

fizcris
active member
active member
@Laitch wrote:
@fizcris wrote:. . .my next step will be to replace the whole electrical ignition system : coils, HT "Realm" leads and Hall sensor. Or do you think I should be focussing more on the fuel injectors and fuel line?
Back on September 25 you indicated you were going to replace the fuel filter? Have you replaced it, or inspected it? Is the interior of the tank clean, are the hoses inside the tank 30R10 type, in good condition and connected well?

The tank looks cristal clear, I have checked the filter and looks quite clean, aniway I have order a replacement just to eliminate unknowns....  The hoses look good with no leaks/cuts.

@Point-Seven-five wrote:Distilled white vinegar is a very food cooling system cleaner.  Get a gallon (4 liter jug) and fill the system.  Run the engine to warm it up and let it sit over night.  Drain and flush with distilled water before refilling with antifreeze.

Cheers for that! I will try that shortly!




@Poupy wrote:Which make/ref of spark plugs did you install?
Are the HT wires original?
How did you achieve your synchronisation? It is not because the depressions are equal in all circuits that the synchro is good. It is important to check that when you tell the injection brain that the throttles are closed (the famous clic when turning the gas handle) the throttles are effectively closed. Otherwise the calculator makes wrong gas mixtures calculations, which can lead to the problems you mention.


For the syncronization, it was done at an expreienced BMW garage so I cannot go deep into the details for that matter. The click when turning the gas handle works perfectly fine, there is a bit of tolerance but expected.

The Spark plugs are NGK D7EA as per recomended. 

Here is also attached some images of the spark plugs in theri current status.

Rough Idle and Missfire when warm Img_2012 Rough Idle and Missfire when warm Img_2013 Rough Idle and Missfire when warm Img_2016
 Rough Idle and Missfire when warm Img_2014 Rough Idle and Missfire when warm Img_2015 Rough Idle and Missfire when warm Img_2017
Rough Idle and Missfire when warm Img_2018 Rough Idle and Missfire when warm Img_2019

Based on those images I think the combustion is quite good now, please let me know if I am missing something.

The HT leads are the original ones and I have had oreder new "REAM" new ones as a replacement as a couple of them fit a bit loose, but I don´t think is causing any out-of-cylinder sparks.

Thank you again for your answers.


Here are some pictures of the current spark plugs status and model.

    

20Back to top Go down   Rough Idle and Missfire when warm Empty Re: Rough Idle and Missfire when warm on Mon Oct 07, 2019 11:43 am

Poupy

Poupy
active member
active member
@fizcris wrote:

@Poupy wrote:Which make/ref of spark plugs did you install?
Are the HT wires original?
How did you achieve your synchronisation? It is not because the depressions are equal in all circuits that the synchro is good. It is important to check that when you tell the injection brain that the throttles are closed (the famous clic when turning the gas handle) the throttles are effectively closed. Otherwise the calculator makes wrong gas mixtures calculations, which can lead to the problems you mention.


For the syncronization, it was done at an expreienced BMW garage so I cannot go deep into the details for that matter. The click when turning the gas handle works perfectly fine, there is a bit of tolerance but expected.

The Spark plugs are NGK D7EA as per recomended. 

Here is also attached some images of the spark plugs in theri current status.


Based on those images I think the combustion is quite good now, please let me know if I am missing something.

The HT leads are the original ones and I have had oreder new "REAM" new ones as a replacement as a couple of them fit a bit loose, but I don´t think is causing any out-of-cylinder sparks.

Thank you again for your answers.
 I would not be that affirmative about the absence of out of cylinder sparks in case of 25+ years old HT leads. Operating your engine in the complete dark without the plate hiding the spark plugs you might see sparks leaving through the leads.

To have a confirmation that the synchro was properly done, watch how your "starter" behaves. When the handle is turned to its maximum, and assuming the cable is not loose, the screw in the middle of the throttles drive should raise by 2.5mm. The shorter that gap the worse is the synchro at the idle speed level (not all 4 throttles closed).
The click is not a sign that the synchro is correct. It is mainly a signal to the injection brain not to inject any fuel in case of engine braking - gas handle at zero - above 2000 rpm. It avoids the "farting" in case of engine braking!

The reason why I asked the type of spark plug was to make sure that you had not fitted one with a R in its code. That R means that the spark plug is resistive, generally around 5 kOhm.
Against parasites the k2v were designed with about 7 kOhm between coil and spark plug electrode. Those 7kOhms consist in 5 kOhm in the HT lead plug side (it is written on them), and two on the coil side. If you mount a resistive spark plug, the total resistance becomes 12 kOhms, which seems detrimental to the spark quality.
Now, if you install a set of RAM HT leads the situation might become opposite... Those leads, which I use on my K1100 since more than 100 000 km, have a total resistance around 2 kOhm only. That lower resistance makes a difference on K1100 (they heat and eventually consume less, probably because of better sparks). For unknown reasons the K1100 feature the same spark plug caps as the k2v, plus resistive spark plugs, which makes 12, a lot against parasites.
If you install a HT line of 2kOhm only (2 in the RAM lead and 0 in the spark plug), you risk to create parasites. I do not think that dividing the total resistance by almost 4 would damage your coils, but better being careful...
So, unless you do not care about parasites and eventually your coils, with your RAM leads, it might be wise using resistive spark plugs, in order to keep the same total resistance as original between coil and spark plug electrode.

    

21Back to top Go down   Rough Idle and Missfire when warm Empty Re: Rough Idle and Missfire when warm on Mon Oct 07, 2019 12:20 pm

Holister

Holister
Life time member
Life time member
@Poupy wrote:... It is important to check that when you tell the injection brain that the throttles are closed (the famous clic when turning the gas handle) the throttles are effectively closed. Otherwise the calculator makes wrong gas mixtures calculations, which can lead to the problems you mention.
The TPS on the 2v K100 its simply a 'throttle closed' switch and a 'wide open throttle' (wot) switch. The 'throttle closed' switch's only function is to signal the FICU to turn the fuel injection off when engine is above 2,000rpm when the throttle is closed. The wot switch signals the FICU to richen the fuel mix when the throttle is cracked wide open.
The TPS can be disconnected without any other effect on the fueling.
The TPS on a 4v is different. It's actually a sensor and not a switch.


__________________________________________________

1989 K100RT     VIN No.  0097367 (naked)  
1996 K1100RS   VIN No.  0451808
 Rough Idle and Missfire when warm Austra12    Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

22Back to top Go down   Rough Idle and Missfire when warm Empty Re: Rough Idle and Missfire when warm on Mon Oct 07, 2019 12:33 pm

Holister

Holister
Life time member
Life time member
@fizcris wrote:
.... was to check the spark plug leads, they were a bit corroded so I clean them a bit and put some Copper Slip on them.
You should use dielectic grease on your spark plugs (over the ceramic part as well as the connector) and in the coil HT lead connections. This will help prevent arcing as well as corrosion.


__________________________________________________

1989 K100RT     VIN No.  0097367 (naked)  
1996 K1100RS   VIN No.  0451808
 Rough Idle and Missfire when warm Austra12    Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

23Back to top Go down   Rough Idle and Missfire when warm Empty Re: Rough Idle and Missfire when warm on Mon Oct 07, 2019 2:47 pm

Arlina

Arlina
Life time member
Life time member
@chris846 wrote:"Replace the bugger"


Hi Arlina, impressed. Is that just a great ability in English, or is bugger a Dutch word too?
Reading too much on international forums and have some fam in Perth, got me bits from there.

Have a good one Smile


__________________________________________________
Rough Idle and Missfire when warm Eu-log10  K1100RS/LT - R1200RT - R1100RS (RIP) - Cagiva SST 350 Ala Verde
    

24Back to top Go down   Rough Idle and Missfire when warm Empty Re: Rough Idle and Missfire when warm on Fri Oct 11, 2019 9:05 am

Poupy

Poupy
active member
active member
@Holister wrote:
@Poupy wrote:... It is important to check that when you tell the injection brain that the throttles are closed (the famous clic when turning the gas handle) the throttles are effectively closed. Otherwise the calculator makes wrong gas mixtures calculations, which can lead to the problems you mention.
The TPS on the 2v K100 its simply a 'throttle closed' switch and a 'wide open throttle' (wot) switch. The 'throttle closed' switch's only function is to signal the FICU to turn the fuel injection off when engine is above 2,000rpm when the throttle is closed. The wot switch signals the FICU to richen the fuel mix when the throttle is cracked wide open.
The TPS can be disconnected without any other effect on the fueling.
The TPS on a 4v is different. It's actually a sensor and not a switch.
You are correct about the k2v tps purpose. I too much think as a K1100 owner. After having had a k100 for a few years Wink

    

View previous topic View next topic Back to top  Message [Page 1 of 1]

Permissions in this forum:
You cannot reply to topics in this forum