Post by: fw66 on June 11, 2021, 09:49:42 PM
Post Update: after a lot of research and troubleshooting, it looks like my engine is over fueling. I have spark, I have compression, I have fuel pressure coming out of the injectors (tested all these things). The bike will start when the spark plugs are left out of the engine for a day or so. After that however, the bike remains very difficult to start.
I've been riding my custom k75 for over 2 years now with no real issues but lately it's been rough idling and popping at low RPM. I initially thought it was bad spark plugs so I changed out the spark plugs and everything worked real well for a day or so, low idle RPM was smooth and the bike torqued really well.
After a few days however, the bike went back to rough idle and bumpy acceleration/popping at low rpm. I began to inspect the bike and noticed there was an oil/gas leak coming from exhaust header 1. The spark plug 1 was also quite wet when I replaced it the first time around.
I removed the head cover and a lot of oil drained out. I haven't done any engine work on the bike as all my custom pieces have been non-engine related. Any direction would be appreciated!
spark plug removal, oily.jpg (60.41 kB . 432x576 - viewed 720 times) exhaust header 1 leak.jpg (61.02 kB . 768x576 - viewed 730 times) cylinder head removal oil.jpg (45.75 kB . 768x576 - viewed 664 times) final removal.jpg (59.27 kB . 768x576 - viewed 685 times)
Post by: Laitch on June 11, 2021, 11:35:52 PM
Usually, when either of the engine covers is removed, some oil will drain out. Buy some sealant like Permatex Ultra Black or Drei Bond (Three Bond) 1209. Either purchase a new cover gasket or clean the oil from your old one thoroughly. Scrupulously follow the gasket mounting instructions in the BMW service manual downloadable from this site, or watch Chris Harris's YouTube video describing valve clearance adjustment of 2V Bricks. When you are ready to mount the gasket, the mating surfaces of the head, cam cover and gasket must be completely free of oil.
After the task is concluded, I advise doing a compression test on the engine when its warm. That will help determine if there could be leaks from valve stem seals, rings or the head gasket. A leak-down test after the compression test will differentiate between those sources. If your preference is just to move on because both the leak and the rough engine performance is stopped by the gasket restoration, I can't blame you. Magical thinking is a beautiful state of being, while it lasts. :laughing4-giggles:
Overfilling of the crankcase with oil could also be part of this problem so pay attention to the oil level in the sight glass and don't fill it all the way to the very top of the ring. I check the oil after the engine has been run then shut off for a few minutes. I want to see the oil level somewhere above the middle dot and just below the top of the ring.
Lurking out in your future are the thorns among the roses—a propane test of the crankcase z-tube and the throttle body rubber manifolds for leaks, inspection of the throttle body vacuum port caps for integrity, a cleaning of the air filter, followed by a valve clearance adjustment, a throttle body balance and a CO adjustment. 177381
Post by: fw66 on June 15, 2021, 03:59:02 AM
So bad news...got the gasket cleaned and replaced, everything is free of oil and used permatex bond in the 4 corners. Started the engine back up, very rough idle once again and then the engine died after about 3 minutes of running.
From this point on, the bike wouldn't start again. I don't have the tools immediately available for a compression test but I'll get my hands on one this week.
Any ideas?
Post by: Laitch on June 15, 2021, 03:31:28 PM
Tools and gauges can be borrowed from most of the major parts houses for only a deposit on them—no fee for use.
Post by: The Mighty Gryphon on June 15, 2021, 03:50:42 PM
Have you checked the breather hose from the crankcase to the air box above the throttle bodies. It is located at the rear of the air box behind the throttle position switch. Remove it to look at it closely. They have a habit of cracking where they are clamped and creating air leaks that mess up the fuel air mixture when starting and at idle. You need to flex the hose a little to see the cracks. If you see even one crack, get a new hose. For testing purposes you can carefully wrap it with electrical tape to see if it improves the running of the engine.
You could also have air leaks around the throttle bodies. You can look into that possibility after confirming the breather hose is okay.
Post by: rbm on June 15, 2021, 04:00:45 PM
Post by: fw66 on June 15, 2021, 04:53:45 PM
@Laitch, so far there hasn't been any additional oil leaks but the bike didn't run for very long after the gasket service before the engine stopped running. I'll have a better idea when I get the engine started again
@TMG, I replaced the breather hose about 2 years ago as I did noticed it was cracked. The new one looks fine so I don't think this is the cause. I'll use some electrical contact cleaner and clean up the plug connectors as they are quite corroded. The sparks I replaced them with were Bosch X5DC plugs, not the NGK's.
@rbm, I'll take a look at that as well, right now my biggest problem is the engine not starting!
Stay tuned for comp test and leak down test results!
Post by: Martin on June 15, 2021, 05:08:05 PM
Regards Martin.
Post by: Laitch on June 15, 2021, 07:01:11 PM
Post by: fw66 on June 16, 2021, 04:25:45 AM
- The bike is turning over, the engine is just not starting. Sometimes when I open the throttle I hear a few pops but that's it
- I checked the fuel injection and I have good fuel pressure and consistent/same jetting on all three jets
- I do have spark, which should mean ignition coils are all grounded and working correctly
@Martin, the plug is usually wet after cranking and I do have spark on the plug as well, perhaps an air inflow issue?
Post by: daveson on June 16, 2021, 05:55:23 AM
Post by: Laitch on June 16, 2021, 08:41:17 AM
Didn't get a chance to do a compression test today but I did check some things off the list:If the engine isn't over-fueling from conditions that daveson described you'll need to commence cleaning and checking the frame ground connections under the tank for tightness to bare, unpainted metal. After that, inspect, clean, and check for tightness the electronic control plug under the tank, the ignition switch connector under the tank, the battery ground strap connection on the transmission; the battery post connections, the Jetronic plug connection under the seat and the starter wiring connections and its bolts. All of these have potential to interfere with starting the engine.
Many of us use DeoxIT D5 because its deoxidation and protection properties have proven effective. Look for it at a music store that stocks electronic equipment or at auto parts stores.
Post by: Martin on June 16, 2021, 05:14:25 PM
Regards Martin.
Post by: fw66 on June 17, 2021, 08:59:22 PM
- 170, 160, 170 on the 3 cylinders
I added a fresh few liters of gas to the tank and tried running the bike again and still the engine won't start.
I removed fuse number 6 and ran it again and same thing, no difference.
Would you suggest I look into getting a new temperature sensor?
I'm wondering if I need to remove the spark plugs for a while to let the engine air out any over fueling (not sure if there is a better way to do this)? It seems that this could be the issue right now.
Post by: rbm on June 17, 2021, 09:41:49 PM
Martin's method will tell you if you are getting gasoline in the cylinders or not. It will tell you if you are getting too much or too little.
What about the injectors? Are they operating? Is there fuel pressure? What is that pressure?
Have you checked the ignition system to ensure the plugs are sparking? The condition of the plugs is very suspicious leading one to believe the ignition wires might be problematic as well. Maybe changing spark plugs and ensuring they are suitable for the bike (caps, resistance, gap) would be prudent.
These bike are victims of poor electrical connections and checking those connections for integrity and solidity will help eliminate many weird symptoms.
Be systematic in your investigation and try to eliminate as many variables as possible which will eventually lead you to the problem.
Post by: Laitch on June 17, 2021, 09:43:21 PM
Post by: fw66 on June 19, 2021, 10:40:38 PM
I left the spark plugs out of the engine for about 2 days to let everything dry up, I started the bike today and it fired up, lots of smoke but it ran well and even was idling well.
Not sure what the issue was, any ideas? Here's what I'm thinking:
1. Rain water got into the gas tank, I was running relatively low on fuel and rode it around for another week and bad water/fuel mixture got into the engine causing things to run very poorly.
2. Over fueling, I haven't gotten around to testing the temp sensor yet but too much fuel flooded the engine and leaving the sparks out allowed things to dry. I'm not sure what else could cause over fueling but just basing it off of what Martin mentioned
Long story short, I think it's possible the leak from the exhaust header wasn't oil. It may have been fuel/water mixture that wasn't combusting? Not entirely sure.
Any thoughts would be appreciated!
Post by: daveson on June 19, 2021, 11:23:16 PM
Post by: Laitch on June 20, 2021, 06:14:29 AM
Not sure what the issue was, any ideas?My first idea would be for you to quit hypothesizing and enjoy the ride. :laughing4-giggles: You don't know what happened. Leave it at that. icon_cheers
Any thoughts would be appreciated!
Long story short . . .
Secondly, if you want preliminary confirmation that you have an oil leak, touch the leaking fluid with one of your fingers then rub that finger against your thumb. If the resulting sensation is oily, oil might have something to do with it.
Post some profile photos of your moto. The fuel tank and the cap assembly is designed to divert rainwater from entering the tank. If you had old fuel within the tank, condensation might have diluted the fuel or the fuel separated.
Finally, you've made a short story long but you have prevailed anyway. Ride on!
Post by: fw66 on June 21, 2021, 08:46:03 PM
It seems that I may have an over fueling issue as leaving the spark plugs out of the engine helped start the bike up again.
I've read quite a lot of forum posts regarding over fueling by now and am suspicious of a few things:
1. Temperature sensor, I'm going to test this for correct values next
2. Possible injector leak? I pulled the whole rail out to inspect fuel pressure in my diagnostics a while back and didn't notice excessive leaking on any of the jets, is there a better way to confirm this?
3. Bad ECU? I know it's pretty rare for these to fail but I read in some forums that replacing this has fixed the problem. Would this be an issue if the jets weren't leaking?
Lastly, I remember when testing the jets for spray, I removed a fuel line with the bike completely turned off and a bunch of fuel was still coming down from the nozzle at the tank.
I'm not sure if this is supposed to happen, could this mean that my fuel pump is faulty?
Post by: Laitch on June 21, 2021, 11:38:24 PM
Post by: fw66 on June 23, 2021, 04:45:53 AM
Thanks for the reminder about checking all electrical connections. I took the time today to remove the tank and check all my connections and here was what I checked:
I cleaned the grounds to the frame and it didn't look like that was the source of the problem.
The connector under the tank was working as expected, no rust looked good.
I pulled the plug off the EFI and connectors look clean, no corrosion.
I suppose based on Johny's post, I haven't cleaned the starter in the fashion that he had mentioned before. I'm not entirely sure if this is looking like a starter issue though because the bike does turn over/crank well.
Any thoughts on where to go next? I read the PDF and perhaps will have to start getting into testing electronics.
I did notice that the temperature sensor had a bit of corrosion around the outside of the body, perhaps it could be causing overfueling?
Post by: Laitch on June 23, 2021, 11:58:00 AM
You still haven't checked the coil wire terminal connections mentioned in Post #8. The terminal sockets can erode then interfere with ignition. In addition, you should check coil resistance.
You're fixated on the coolant temperature sensor. You should probably get that fixation out of your system. It can be tested electronically or by removal using the boiled water test; both tests are in the troubleshooting guide. I suggest you do both tests; that should cure you. :laughing4-giggles:
You've got plenty of fun ahead—fuel pressure testing, injector coil pulsation, air flow meter vane ease-of movement. Just remember, when you ask a question that starts with "Could it be . . .," you may as well consider "Yes" as the answer.
Post by: riots100 on June 23, 2021, 03:55:03 PM
http://www.motobrick.com/index.php?topic=7661.msg57782#msg57782
There are similarities and solutions to be noted.
Post by: fw66 on June 23, 2021, 09:27:04 PM
I took the coils off today and cleaned/inspected them- connections look secure and aren't corroded. I have an ohm meter but am not quite sure what to test for since the PDF guide is for the k100 coils.
Are the values and testing method the same for the 3 coils on the K75?
Furthermore, it's more unlikely that the coils are damaged if I have confirmed that I have spark on ignition for all three spark plugs right? Or is there something I'm missing here?
Some things I am going to be getting to:
- Testing fuel pressure for exact pressure numbers. I skipped this part because I pulled the injectors and checked for spray pattern/leakage and it looked good, vacuum tube to throttle body 3 was also not leaking or smelt like gas. I'll have to confirm fuel pressure once I put the bike back together.
- Test/replace temperature sensor, the sensor has a blue-ish hue on the nut which doesn't look like it's in the best shape, not sure if this would be the exact cause.
- Doing more research on the hall effect sensors? I've read this is a possibility...
Post by: Laitch on June 24, 2021, 12:35:39 AM
. . . it looked good.What you're missing here is that looks aren't everything, a fact marriage counselors everywhere will confirm. :laughing4-giggles: Testing helps determine fault.
Furthermore, it's more unlikely that the coils are damaged if I have confirmed that I have spark on ignition for all three spark plugs right? Or is there something I'm missing here?
There are always more questions. Is there enough spark? Is it consistently produced? Is there too much fuel or not enough? Are all the injectors pulsing or are some opening but not closing? Is the air filter clogged enough so the fuel mixture has become too rich? Is the vane in the air flow meter not pivoting smoothly or just plain stuck in one position? What is the condition of each plug after a failed starting attempt? Is the fuel filter clogged? Are the fuel lines in the tank tight? Are the line interiors restricting fuel flow? It's just one test after another.
K75 coil resistance is tested by the same method as the K100. Primary wire resistance is approximately 0.8Ω, secondary is approximately 10KΩ.
Post by: fw66 on June 25, 2021, 02:56:43 PM
At room temperature, I'm getting a resistance of 4.2k ohms which is not in spec as it should be 2.5k ohms. This is a clear indicator that the temperature sensor is not working as it should be and potentially a cause to my over fueling problem.
The sensor is sending incorrect data to my EFI that the temperature is almost freezing and probably sending too much fuel into my injectors.
Let me know what you guys think!
Post by: The Mighty Gryphon on June 25, 2021, 03:45:36 PM
What is the resistance when the sensor is submerged in boiling water? Should be a bit less than 250 ohms.
Post by: fw66 on June 25, 2021, 05:50:49 PM
Well now I know the temp sensor isn't working to spec and have a new one coming Tuesday, hopefully this will clear up my problems.
Since I removed the airbox, I have access to the fuel regulator as well. Is there an easy way to test if the regulator is functioning properly?
Would it be beneficial to replace is (my bike is a 1990) anyways to prevent future fueling issues?
Post by: Laitch on June 25, 2021, 07:08:04 PM
Would it be beneficial to replace is (my bike is a 1990) anyways to prevent future fueling issues?The easy way to test the fuel pressure regulator is on a running engine using a pressure gauge. If the fuel pressure regulator works, leave it alone. Your replacement FPR could be defective. Spend money on new fuel hoses and a couple of cans of DeoxIT D5.
Post by: rbm on June 25, 2021, 08:34:00 PM
To be transparent, you're supposed to measure terminal to body. If you measure terminal to terminal, you're doing it wrong.
Post by: Laitch on June 26, 2021, 12:08:26 AM
To be transparent, you're supposed to measure terminal to body.How long do you stay transparent when you do that? There are some discussions in town selectboard executive sessions that I've always wanted to hear. :laughing4-giggles:
It's too early to start the party, fw. 177381
Post by: fw66 on June 30, 2021, 08:25:09 PM
Put the bike back together, new temperature sensor, new HES sensor, changed oil and coolant as well.
Put the new spark plugs I put on brand new just a few weeks ago and the bike fired up, smoked a lot and continued to run. Turned off the bike and the bike won't start again...
Had an extra set of spark plugs, changed all 3, bike fires up and runs super well.
I have no idea what happened but is it possible that the brand new spark plugs that were just replaced about 3 weeks ago got fouled due to water gas mixture and was causing the same poor running/starting issues?
It's strange that I did see sparks on all three when testing them for spark...
Post by: Laitch on June 30, 2021, 09:16:52 PM
Could the new plugs have been fouled? Sure and you could get an idea of their condition by looking at them. You should consider testing both the ignition control unit and the fuel injection control unit by the methods described in the troubleshooting guide, a link to which can be found at the end of the first post in the Repair Guidance section.