CB1100 Idle speed instability problem

[peterbaron]

Max, just to verify, the resistors in post #1326 you identify as 220 ohm, and the ones you settled on in post # 1355 are 330ohm, right? And the ones I should install are the 330 Ohm? Or does it really matter?
Thanks again.
PS, I won't try this out until probably late September when the temperature in my garage drops below 90F (or 30C).

Completely understand Nacho, all in good time.
The resistance of one of the two windings of the iacv is around 100 ohms, the ecu checks this value constantly and if it decides the iacv has an open circuit it sets a code ( orange cel ) and puts the engine in " limp home mode" ; 5000 rpm limit.
So the ecu checks the current through the iacv windings, the minimum value resistor is 390 ohm before it sets an alarm, so any value resistor between 100 and 390 ohms is sufficient for the ecu to not set a code, the voltage across the windings is 12 volts according to my oscilloscope, so at 100 ohm the current flow is; 12:100=120 mA with a 50% duty cycle during iacv activation which is o,72 watts ( at 50% duty cycle ) for short periods of time.

So a 1 watt resistor of 100 ohm would work fine, but the same result can be achieved with a 390 ohm resistor, the power dissipation would now be; 12v x 0.03 A= .036 watts.
I tend to choose to do the job with minimal current draw but still reliable so i chose the 330 ohm resistors since they are also used to load the o2 sensor heater when unplugged, ( the ferret's o2 mod ) so it is a bit of a universal value.

So anything between 220 and 390 ohms will work equally well provided the power rating of the resistor is 1 watt, smaller than that means the reliability is compromised and the wire size of the resistor leads becomes too small to fit reliably in the connector,( 0.6 to 0,7 mm., too big a resistor would have larger wire diameters and be more difficult to insert into the connector and the connector's contacts would be splayed out too far in case it had to be re-connected to the iacv.

The 1 watt version i used fitted nicely into the connector if inserted 10 millimeters into the body of the connector, initially i did not insert them deep enough and the orange cel lit up so i re-inserted them a bit deeper at 10 mm.

Long story but now you know why .

Max, your willingness to perform exploratory surgery on your bike when you don't have the problem yourself is admirable. This makes me wish I still had my 2014 standard (which had the high idle problem) so that I could test this fix to see how it works...almost wish, I mean.

....Max, your willingness to perform exploratory surgery on your bike when you don't have the problem yourself is admirable. ......

Yes, you're extremely helpful, Max, on this and other matters, I've noticed. Top man!

^+1^

[GoldOxide_imp]

Max is some sort of Forum hidden stealth angel.

[Cormanus]

Yes, you're extremely helpful, Max, on this and other matters, I've noticed. Top man!

^^

[Nachodaddy]

Thank you, Max. I understand much better now. I love learning new things at my age and this problem has become a blessing in disguise only because you are there with very creative ideas and a brilliant understanding of how this all works. I will keep you posted on my progress.

[max]

Very good Nacho, i'm glad you get it.
The prize for me is the smile on your face when it works for you and you then have your bike back to enjoy.
.
Also hope that some of the affected members can go back to their dealer and say " i fixed the problem permanently for one dollar " and then NOT tell them how it was repaired......" it's a trade secret ".......justice served

You guys had to put up with a lot of unnecessary grief, obviously not fair treatment to you and that is not what you paid for.

Thanks for all the nice comments, it's appreciated.

[Tev62]

So, anybody trash the fuel injection and replace with carburetors yet ?

As the owner of a 1995 Triumph Daytona 1200 which plagued me with fueling problems for a year I am really happy with the fuel injection on the CB.

[whizzle_dizzler_imp]

Guys, update. My lazy butt finally got the resistor mod done.

I've been riding with two 330ohm 1w resistors stuck in my IACV plug for about a week now.
My experience:
On startup, bike kicks on, and has a considerably lower idle than before, around 900-1000rpm. Prior to the mod, it was consistently idling at 1200+rpm, even after warm.
A short ride around the neighborhood for a couple miles, the idle does not change and rev high, and still runs like a normal motorcycle.
Once I get some miles in (I commute 20mi both ways during the week), and the bike heats up, it starts running just about the same without the mod, revving high while in gear with the clutch pulled in, revs ramp up when letting the clutch out, and only drops the revs when putting the bike in neutral.

I'm not sure if the resistors are heating up too much and losing their ability to..... resist?

I haven't tried any other resistors yet, as I wanted a baseline on how this would perform over a week of riding.

So unfortunately the resistor mod has not 100% fixed my issue, maybe I'll bump up the resistance and see if there's a change.

[Nachodaddy]

whizzle_dizzler, I am glad you tried this fix and I hope you can eventually get it to give you the results you want.
On my 2013 standard, my final and complete fix was to replace the ECU, or the PGM-FI unit.
Original part number is: 38770-MGC-A23, however, when I put that number in at Partzilla, the number changed on the screen to 38770-MGC-A24, which is what they sent me.
I see ads for the 23, but I think the 24 might be an improved version and mine is working the way it should be. It is not cheap (Partzilla is the best price) but it works and it is easy to replace.
Best of luck and keep us informed.

[PowerDubs_imp]

There was just a post by another guy who is looking into a cable to be able to tune the ECU.

If he can read / write the file- then he could read a '24' box and flash it to the older boxes for everyone.

[1973cb750]

Trying to learn but not sure it's possible with what I have yet