Try checking the quality of the connection to the engine temp sensor on the front cylinder intake valve cover. I had very similar problems with my 900ie and when I checked, the spade connectors were a lovely shade of green. If the ECU doesn't get a good reading from this sensor, it assumes the engine is stone cold and runs the injectors fully rich (like having a carb on full choke) I just cleaned up the connectors and all was fine, put a smear of battery grease on them to help prevent it again.

 

Hi Tony,

A few people have said this may be the issue, but the dealer confirms that the sensor is giving a good reading.

Others have said a possible ECU problem??

 

I took the bike back to Daytona who made further adjustments using the fuel injection computer, the bike now runs worse. Under load (accelerating) its ok but trying to maintain a constant speed around town 20 - 30 mph is a nightmare, its just keeps coughting & splutering.

I have looked at the oil temp sensor and the terminals were quite green, I have now cleaned to the best of my ability but to no change. I did try and remove the OTS by unscrewing but it just kept spinning, should this be hapening?

So the bikes performance does inprove when the dealer makes adjustsments to the fuel injection system, but they cannot cure the coughing & spluttering at crusing speeds?

Are Oil tempreture sensors prone to failing & would it be worth changing?

all suggestion welcome!!

 

hi steve.
i have a 2005 620ie dark and i had experienced the same problems you described.
my bike sputtered and surged above idle to about 4700rpm. it was such a horrible way to ride. most of the time my bike would not idle with out the help of me holding the throttle open to keep it alive. if it idled alone while warm, it would stall constantly. i too had to use to the choke to keep it running at idle.

i took the spark plugs out and they were full of dark carbon from being too rich.

i bought and installed a PC3 usb and used a map which is designed for stock intake with aftermarket exhaust ( i have sil motor carbon cans on) . with a fresh set of plugs and the PC3, my bike ran great for about 200 kms and the problem was back.

so i then took it to a performance shop (approved dynojet retailer) and had the 20,000 km tune up done with advanced cylinder mapping. they did the tune up, then put the bike on the dyno for 9 hours tuning each cylinder individually.

they also upped the idle to 1800 rpm, a bit high but keeps the motor alive.

after the work, i gained a few horsepower and a bit of torque, but the main thing is the way the power is now delivered. smooth and strong. all the problems are now gone.

i hope this helps , msg me if you have any questions.

 

To remove the engine temp sensor, 1st remove the inlet valve cover, c/w sensor etc, on the inside of the cover you will see a circlip holding the sensor in place. Just remove the circlip and the sensor pulls out of the cover. Keep an eye on the two O rings, you might want to replace them when you re assemble. I didn't and had no problems...but....

There's probably a range of resistance readings you should get at various temperatures....anyone help with this?

 

I strongly suggest doing compression and leak-down tests on your bike. Once you have that data, you can make better decisions.

 

Im having this exact problem with the exact bike model. Did you figure out what was the problem?

 

My Sensor is working
The injectors are fine and serviced
I have a brand new fuel pump
New plugs
This bike keeps fouling plugs due to overfueling.
I have a vagkkl and fiat cable which is a pos
Ive ordered the bluetooth adapter to try and fuel trim with the android.

 

Any update?

 

Im just waiting for the eml blutooth adaptor to arrive. Will keep everyone posted as i troubleshoot.

 

Well just my luck the elm bluetooth adaptor does not work with the 1.5M ecu.
Anyways i realized my tps setting (idle backed off) is 1.5V vs the nominal setting of 150mv. If i set it as 150mv the bike does not even start and backfires. Can the tps setting change the timing on the bike? It seems like trying to start a badly timed bike at 150MV. At 1.5V it actually starts and rides well but burns waaay to rich and have problems at full throttle.
What is going on here? ???

 

Be sure to check the timing directly using the actual position of TDC. The timing marks on my original flywheel were 20 degrees off.

PhilB

 

Will check it out now.

 

The cams are dead on timing but the magneto seems a tiny bit off. Will this cause a problem?

 

 

I took the plugs out put her in 2nd, and turned the back wheel till the TDC stroke was on the pointer. The cams mark were still lined up straight, so i guess the timing is good.

 

Fixed it!!
Ok turns out my temp sensor was sending crazy readings to the ecu.
I set the tps to 150mv and connected a variable resistor in series with the sensor. I eventually found the sweet spot where the bike's mixture is idea. The advantage i have now is i can either lean out or richen the mixture my modulating the dial on the resistor. My bike finally works and runs amazing. I wish i cud send pics for you all to see my invention lol. but the size is restricted.

 

Post any and all pictures to an online site and send us the link. Make sure the site isn't password protected. If you have Dropbox, you can send a Public link and we can view them there.

 

https://www.dropbox.com/sc/n45bor1inudytbk/AADUr0YE4_9AAhg49Hb396qta

link to pics

 

Great work. It's amazing what can be done with an idea and some sweat.
I knew the temperature readings (oil and air, and coolant if so equipped) feed into the ECU and I've seen devices that you could adjust but I've never seen this done on an older air cooled 2 valve.
Thanks!!

 

Ive had this bike for months and it never ran good. I never gave up tho, and i know this info will come in handy for alot of people. I just had to share with everyone. Its such a cheap fix/diag. This resistor can be found on most car audio amplifiers. Its the remote control that adjusts the gain on the amp. Range is somewhere from 0 no resistance to about 8000 Ohms which is more than enough for modulating the bikes air fuel ratio.

 

Alex, can you post some symptoms you were experiencing that adding the variable oil temp sensor switch fixed?
I also have an M900 and when I'm running hard in the mountains, my bike will start popping and backfiring when it's under a load. I changed the CO trim setting from 5 to 40 and it took most of that away but I'm still getting some. I'll increase the CO value to 45 or 50 and see it that eliminates it completely but I'm thinking a faulty oil temp sending unit might be the real culprit.

 

OK i've had many small problems with this bike. At first when i give throttle it would bogg down like a carbie bike thats starving for gas. So i decided to check the fuel system. I found the line after the fuel pump to the filter ruptured, so some gas was going to the rail and most was just spraying in the tank due to the ruptured line.
There i thought my problem was sloved when i replaced the line. At that point i can give full throttle but the bike was backfiring and coughing. It was a mess to ride. She used to foul plugs within minutes. The bike was burning very rich. I read some posts saying tps may be my problem, so i did the tps, and it worked worst.
So i adusted the tps by ear until i thought the bike sounded good. My value was a entire volt higher than spec. But the bike was rideable. She guzzled gas and gave people a nice flame show at nights. When i did some more reading i realized that my tps was way off even the adjustment at idle was looking weird because to myself i knew i had too much travel initially.
So i decided to factory set the tps and look for other issues. So we have 2 temp sensors that feeds to the ecu. One is on the horizontal cylinder and the other is behind the headlight. I took the one from the headlight connected to a resistor and blew my hot breath on it to see if anything changed.... and it did, was actually very sensituve. I realized these sensors work with resistance, that sends the value to the brain. So e.g. the hotter it is the less or more resistance value will tell the ecu to either lean out or richen. Now the tps mv value will only send the amount of fuel not the air fuel ratio.
Because i saw better milage once the tps was at a lower value despite the bad temp sensor i had.
Now i realized the temp sensor was bad although it was changing resistance values with temp. So i took it out completely and installed the var. resistor. It started fine but my problem was when the bike gets warm it started to burn too rich. Then i decided to connect it in series with the old sensor. This was much better. So the sensor apparently drifted or had a tolerance gap that the VR was now filling.
But during the tuning period i got small intake backfires at low RPMs. Like now pulling off and stuff, made me bogg and cut-off a couple times, but over 2.5 rpms was healthy. Turns out the mixture was too lean. I adjusted the resistor slightly to richen a couple times and finally got it right. Now the bike it perfect. I pulled the plugs last night to inspect the burning, its beautiful and clean. I am satisfied with the bikes performance now. It never pulled so smooth through the rpms, especially low rpms 4k and lower. Now i can cruise at 2.3- 3k comfortable.
I will measure the resistance across the resistor and sensor cold and hot and post it, so people will have a good base value, if they decide to give it a go.

 

Looking forward to your posts.