How to check faulty ISC on DT300

[francuz69]

Hi there,
after having and resolving electric issues with rectifier and some other things, everything was working fine. Had a new set of tyres - Pirelli Diablo Rosso. Fantastic rubber...
But now i am having another issue. DT on startup works fine but after few kilometers/miles of riding it begans to stall when stoping. Normally it idles around 1600-1700 RPM but after a short ride it falls to 1000, sometimes even lower...
I can do a workaround by slightly giving a throttle when stopping but it can be very annoying.
Fuel is new, tank doesn't make a vacuum and a swoosh sound when opened, sparkplug is brand new CR7E, and i have a beautiful spark. No clogged or pinched hoses. Everything seems perfect except that stall on idle after few miles.
Which leads me to one thing. Few days ago when i turn the key to on, I've used to hear a buzzing/clicking sound which comes from ISC. Now i don't hear it anymore. Could it be that ISC died on me?
I've read all topics on stalling regarding DT300 and also read the service manual, but i can't seem to find the procedure on how to check is the ISC faulty or not. Only thing i have found is this guy's post on YT regarding ISC operation but i doesn't say how to check a faulty one:
Also, one more question regarding ISC/TPM reset procedure... How to know did i perform it well. Does some signal lights up on the dash when a reset is performed or not. I suspected that ISC maybe got "unpaired" with the scooter while i have removed it for visual inspection, but i can't be sure did the ISC/TPM procedure go well or not.
Hope someone has the answer...
Best Regards

[CROSSBOLT]

Welcome! if no one has said that yet!

Your initial trouble shooting is faultless! Even addressed the thing I dearly love to harp about: gas tank "whoosh!"

The service manual is mute on testing the ISC. It is but a 5 volt motor operated valve that controls idle. There are four wires that go to it, two are power and two are feedback to the ECU. I don't know which are which.

There are three things I would do if I were experiencing your symptoms on my DT300i:
1. Check every connection between ECU and throttle body by disconnecting, inspecting and applying silicone dielectric grease before reconnecting.
2. Remove the ISC from the throttle body, with the connector plugged in turn key on and see if the thing runs. I would suspect it would retract a plunger or change something. Never had mine out so am guessing.
3. Pull the injector, with the connector plugged in turn key on and see if it sprays. It should spray out of all 5 holes (so small nearly invisible!). Reverse the injector if no spray or if lopsided spray pattern. "Reverse" means disconnect the pressure hose from tank and pump and push it on the spray end of injector! Then cycle the key on and off for several complete self-checks (where the tach and speedo do their full scale dance, the fuel pump runs and then everything stops). This will probably clear any crud out of the injector by back-flushing. Worked for me on fail to start.

There is no bell or whistle for a successful ISC/TPS reset. Have you noticed any flashing of the CELP light on the panel? Turn key on but don't start. Engine shaped yellow light will go out after a bit and then flash short and then maybe long and then short flashes. Those would be trouble codes. Let us know what you find.

[francuz69]

Thank You Crossbolt for helping me out with Your advice once again!

I definitely have a problem with ISC. If You look at the YT video i have posted yesterday, You can see the exact procedure You described in step 2.
And in video You can hear buzzing/clicking sound i have described in the first post.
The problem is definitely in the fact that i don't hear that sound anymore. I've heard it before, every time i gave key contact to my DT.
Looking back, i can conclude that few days ago, when i went to service for tires change everything was fine, but when i picked up my DT, idle speed was high, about 2500 revs. It was strange to me, but that day was cold so i thought it is normal. When i came home, i have dissconected ISC and cleaned it with a soft rag, because it had some black gunk on it. Turned it back, screwed it on and plugged it back in.
Next day my symptoms began. No clicking/buzzing sound and when machine warms up, low idle/stalling problems emerge.

Since manual says that every time ISC or TPS is disconnected, You need to do the ISC/TPS reset procedure, i suspect that ECU and ISC won't "talk" anymore, so i have tried the reset procedure few times, but no luck.
Now I'm scratching my head, on how to test ISC, how to be sure that reset is 100% performed or how to repair ISC if it's dead...

I am currently on a business trip, so i will give it a go with contact cleaning and testing before anything else. Will write about it...

[Dan Hartmann]

I do not know if this can help you.

TPS/ISC RESET PROCEDURE
1. Put the side stand up and engine stop
switch is at “RUN”.
2. Turn the key to the OFF position.
3. Fully open the throttle.
4. Turn the key to the ON position.
5. Release the throttle after waiting for eight
seconds.
6. Turn the key to the OFF position.
7. Turn the key to the ON position.
8. TPS and ISC have been reset successfully.
If fail to reset, repeat the steps from 1 to 8.

[CROSSBOLT]

I FINALLY watched the youtube and listened. The sound is typical of a stepper motor which makes sense in this application. Steppers are the simplest of all motors and will work if there is power in sequence. Bet there is a contact problem in that connector! Or the connector at the ECU...

[de dee]

  FEELS LIKE IT HAS SOME BLACK CRAP ON THE PINS and shorting out ,. 

[francuz69]

Some new development in this case.
Yesterday i have played with throttle body. Checked wiring connections and everything seams clean, fine and well seated. Tested ISC few times. When i turn the key to on, nothing happens, but i saw that when i turn the key to on with the throttle wide open, the clicking/buzzing sound from the ISC appears.
I pulled out ISC and gave it one more turn of the key to on to see how it pulls in and out and saw that the ISC pin is a little distorted to the side. Probably i have done that by mistake when i have pulled it out few days earlier. I have corrected it by hand and screwed it back to the throttle body.
After done that, i have started the motor, left it to warm up, drove it a little while and everything seemed ok. Revs didn't drop below 1500-1600.
But now i saw one more thing.
When turning the key to on, and waited for CELP to give me error codes on the dash, error 09 appeared.
The DT 300 manual says that error 09 should be faulty MAP sensor. Now, how to check for faulty MAP and how to test it? Also, can i clean MAP with carb cleaner spray, because manual says that the throttle body can not be cleaned with carb cleaner, cause inside of throttle body is coated with molybdenum which can be damaged with cleaner?
I saw the article on this forum where one member played with MAP position which helped him with inconsistent revs. When looking from the left side of the bike, my MAP is positioned around 1 o clock and that member said that in his case ideal position was around 11. Even in some pictures on the internet i saw that some MAPs were positioned at 9 o clock.
Any thoughts on this one? How to test is it faulty and what is the best position for it?

[Stig / Major Tom]

So, it's running fine now - but if you wait you can get an 09 code to come up?
I'd ride it several times if it is showing 0 ill effects. ... watch things closely, see what happens.

Stig

[francuz69]

Still cold for a bike over here so i am not able to drive. Morning temperatures are issue, when i'm leaving to work. I think tomorrow will be a little warmer so i will probably give it a try.
Yesterday i was playing with throttle body. I have concentrated on TPS. Thought it has something to do with my idling issue. Measured it with multimeter, but everything is fine. If someone needs a procedure on how to measure TPS, here it goes:

Definitely it seems i have a problem with a MAP. Error 09 stays on on CELP. Except that and the fact that my idle revs are around 1500 instead of 1700 everything seems ok.

[francuz69]

Well...
i'm proud to say that i have resolved my problems.
As You know i have played a lot with my throttle body, TPS, ISC and MAP sensor. After everything checked and cleaned the bike was not stalling any more, but idle revs were around 1500 which is slightly lower than i prefer.

So, i have rebuilt transmission. Previous owner was a little cheap, so the belt was wrong, rollers were RMS (rubbish) and everything was filthy.
Changed rollers for Polini, belt Mitsuboshi, cleaned everything and lubed where it should be lubed. On inspection i saw that old belt was few mm longer and a mm narrower. Of course it was slipping on idle.
I suppose that previous owner put that belt because original/Mitsuboshi is quite expensive so he was searching for the next best thing.

When i finished everything i did one more thing. And whatever anybody thinks, this step is really important. I have removed MAP, and lubed a small rubber seal underneath it with a little drop of engine oil. Put it back and made connection to the throttle body real tight, tightened the screw like crazy.
After that everything works as a charm. Revs do not drop beneath 1600, no stalling, perfect!
Still had a 09 error on CELP, did reset procedure:
Key on, wait 10 secs, throttle wide open for 10 secs, release throttle, wait for 10 secs.
Now the CELP is silent.

Now i can ride like a man!

Thanks everybody for  help, especially Crossbolt...

[CROSSBOLT]

Thanks for the follow-up! This is added to the trouble shoot ecyclopedia which is NOT in cyclepedia!