Honda CB1100 Rough Idle Solution

[zirconxi_imp]

I see no sensor under my seat and compartment box. Only have a fuse box. Could it be the seat is putting pressure on the fuse box and cause loose electrical contact??

[dickie1951_imp]

According to the Honda CB1100 shop manual the Intake Air Temperature (IAT) sensor is under the left side cover and fastened to the rear air cleaner housing with two screws.

[SportsterDoc]

Regarding the manual:
Note the symptoms/fail safe function of all DTC on pages 5-15 and 5-16 of FSM.

The IAT defaults to 95 degrees F.

Suggest that the OP verify that the air filter is clean, look for a vacuum leak, check condition of spark plugs and ensure that the battery cables are well secured.

[dickie1951_imp]

Thanks for the suggestions. A few thousand miles ago I replaced the air filter and spark plugs as part of regular maintenance. And I re-installed the battery for spring two months ago being sure the terminal connections are tight.

The fluctuating idle has not recurred for over three weeks since removing the stack of bungee cords from the under-seat compartment. I have been riding my bike almost every day over that time.

Prior to removing them, the fluctuating idle would occur intermittently two or three times over a 30 minute ride.

It is the lack of any more fluctuating idle problems over the past three plus weeks that makes me think there is nothing mechanically wrong with my bike. The idle has always been smooth during that time.

To confirm that the stack of bungee cords are involved, in a few days I will put them back in the storage compartment and try to reproduce the idle problem.

[Houtman_imp]

Chinese made bungee cords ?

[dickie1951_imp]

Very good! :-)

Maybe?

[Charlie Bravo_imp]

I put a resistor in the wire from the temp sensor to the ECU to spoof it and make it add more fuel to stop a serious ping on my Kawi Nomad. It worked, but the best solution was one of those four-pot fueling regulator, plus rerouting the intake air stream, removing the idle air injectors and drilling the muffler. Right about when I had it running the way I wanted, my wife said she could not ride with me as long as her mother is still alive and kicking. I sold the bike.

[SportsterDoc]

Thanks for the suggestions. A few thousand miles ago I replaced the air filter and spark plugs as part of regular maintenance. And I re-installed the battery for spring two months ago being sure the terminal connections are tight.

The fluctuating idle has not recurred for over three weeks since removing the stack of bungee cords from the under-seat compartment. I have been riding my bike almost every day over that time.

Prior to removing them, the fluctuating idle would occur intermittently two or three times over a 30 minute ride.

It is the lack of any more fluctuating idle problems over the past three plus weeks that makes me think there is nothing mechanically wrong with my bike. The idle has always been smooth during that time.

To confirm that the stack of bungee cords are involved, in a few days I will put them back in the storage compartment and try to reproduce the idle problem.

BOTH ends of BOTH battery cables checked?

Vacuum lines intact?

Check all the hoses, including 4 way and 5 way vacuum fittings?

A crack would suck air and increase idle...unless the crack got bigger than it would decrease idle.
Be good to replace with brass, but finding more than a 3 way would be a challenge.
The 5 way (part 18) is 17201-MCJ-003 ($7 list)
The 4 way (part 19) is 17201-MCZ-003 ($5.60 list)

https://www.bikebandit.com/oem-parts/201...#sch848000

Not stating that this is the problem, but worth checking.

[Houtman_imp]

I put a resistor in the wire from the temp sensor to the ECU to spoof it and make it add more fuel to stop a serious ping on my Kawi Nomad. It worked, but the best solution was one of those four-pot fueling regulator, plus rerouting the intake air stream, removing the idle air injectors and drilling the muffler. Right about when I had it running the way I wanted, my wife said she could not ride with me as long as her mother is still alive and kicking. I sold the bike.

You picked your mother in law over your bike ???

[Charlie Bravo_imp]

I put a resistor in the wire from the temp sensor to the ECU to spoof it and make it add more fuel to stop a serious ping on my Kawi Nomad. It worked, but the best solution was one of those four-pot fueling regulator, plus rerouting the intake air stream, removing the idle air injectors and drilling the muffler. Right about when I had it running the way I wanted, my wife said she could not ride with me as long as her mother is still alive and kicking. I sold the bike.

You picked your mother in law over your bike ???

You picked your mother in law over your bike ???
I was already considering selling it, too big and too heavy for everyday riding, and it was developing electrical problems too.