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+--- Thread: Really high idle (/showthread.php?tid=4483)
RE: Really high idle - Lord Popgun - 11-10-2021
PB, doing diagnostics, replacing and adjusting the TPS isn’t hard. Remembering a part number? CRS…
RE: Really high idle - peterbaron - 11-10-2021
(11-10-2021, 08:49 AM)Lord Popgun_imp Wrote: PB, doing diagnostics, replacing and adjusting the TPS isn’t hard. Remembering a part number? CRS…
....me neither
RE: Really high idle - SportsterDoc - 11-12-2021
For the benefit of those referencing this thread in the future, below is from post 1159 of the CB1100 idle speed instability thread.
For Gordo, since there have been a couple TPS issues reported, best to check TPS voltages, as suggested by Max.
It does not seem to be a MAP issue, due to symptoms not matching.
It does not seem to be an EOT issue, per reports in this thread and symptoms not matching
It does not seem to be a TPS issue, due to the recent testing guided by Max. There may have been one or two TPS issues, but not for Dave.
Manual pages 5-74 and 5-75 cover IACV (symptoms seem to match): One check is to listen for the sound of it cycling with key on and stop/run on. There is a caution about cleaning before removal to prevent debris in the IACV passage...therefore, any debris would be a concern to proper operation.
Note the symptoms/fail safe function of all DTC on pages 5-15 and 5-16 of FSM.
In the b&w photo at the bottom of page 5-74, it is not sufficient quality to see any air ports to the sides of the passage. If IACV replaced, without cleaning, an IACV issue may remain.
The IACV is 16430-MJF-D01 (later model 16431-MJF-D01), but Dave successfully used 16430-MJF-D01
The IACV can be tested, per the factory service manual:
IACV testing, per FSM 15-41 & 15-42:
Note: These tests may be done with IACV mounted, by lifting rear of fuel tank and removing right side throttle body cover.
1. After clearing stored DTC, per page 5-14, recheck for stored DTC 29-1. If none, then prior DTC was intermittent.
2. Measure resistance of each of the four wires at the ICAV connector (disconnected, harness side, not IACV side). Continuity to ground should be infinity. If not, the wiring harness has a short to ground.
3. Check continuity to ECM, from disconnected ECM 33 pin to disconnected IACV 4 pin connector
Positions are numbered with locking tab up:
ECM A6 black/yellow to IACV connector postion 1 (left)
A17 black/red, position 2
A16 black/blue, position 3
A7 black/orange, position 4 (right)
4. Measure IACV resistance, (IACV side, disconnected), facing with locking tab up at airbox side (mirror image of connector):
position 4 black/yellow (right)
position 3, black/red
postion 2, black/blue
position 1, black orange (left)
a. black/yellow to black orange (2 outside positions), 99-121 ohms at 77F/25C
b. black/red to black/blue (2 inside positions), 99-121 ohms at 77F/25C
If resistance out of spec, FSM declares IACV faulty
My 2 cents: If IACV and wiring tests good, then if symptoms continue to point to IACV, it may be a piston travel issue or air port issue.
Summary, to date:
Max started a very comprehensive thread on the IACV.
http://cb1100forum.com/forum/showthread.php?tid=12203
Post 9, Feb 19:
vacuum loss (minor = high idle, major = close to stalling/stalling)
TPS (FSM symptom/fail safe: hard to start cold)
IACV (FSM symptom/fail safe: engine stalls, hard to start, rough idle
EOT (FSM symptom/fail safe: poor acceleration)
DTC 29-1, FSM page 5-16, lists IACV circuit malfunction as "loose or poor contact of IACV connector, IACV or its circuit malfunction".
Otherwise, per the FSM, other sensors failsafe is normal engine operation, this includes MAP, IAT and O2. There is no mass flow sensor or exhaust temp sensor on the CB1100.
The FSM incudes all sensors on pages 5-15 and 5-16.
Symptoms reported are classic for IACV.
The piston not moving as much as the stepper steps would not likely provide a DTC (opinion) and this may be more likely than any other aspect of the IACV operation.
Post 11:
Just glancing at pages 5-15 and 5-16 shows how well the CB1100 will continue to perform with many sensor codes.
If the EOT is wonky, the only issue is hard starting cold.
If the IAT is wonky, default is 95 F.
If TPS is wonky, default is 0 degrees position
If an O2 sensor is wonky, "engine operates normally"
However, if a fuel injector faults, it is time to push: Engine does not start, injector power, pump and ignition shut down in the event of "loose or poor contact of the fuel injector connector-fuel injector or its circuit malfunction"...fail-safe is not just complete failure...it is out of spec parameters.
Post 16:
The "advantage" of purchasing the entire throttle body assembly is that the IACV port would be clean, not warped, with new IACV and new TPS.
...hearing the IACV cycling indicates that the stepper motor is stepping or trying to step. If crud is preventing full operation, it may not sound much different. The ECM has no feed-back regarding actual movement.
Really high idle - Gordo_imp - 11-12-2021
It's been long week and haven't been able to get to the bike. My issue started on a hot afternoon and sitting in traffic! I noticed that high idle could be related to a vacuum leak as well. Last weekend when I had it all apart I checked all the hoses and such were connected properly, and they were. Sunday I'll pull out the volt meter to give me a more accurate idea. I'm thinking I may also order the updated iacv, if I can find one. I went out and started the bike last night before leaving for work. It started immediately at 1500rpms and creeped into the the 1700 rpms as the motor heated up.
Titus 2:13
2013 HONDA CB1100
RE: Really high idle - max - 11-12-2021
Have you listened to the iacv on key-on with the fuel pump relay removed?
Does it sound like it behaves like the video suggests?
There are many things you can try but until we verify the iacv is moving or not we go around in circles.
And on the off chance; is it possible you installed the defective iacv?
Just trying to help you.
Really high idle - Gordo_imp - 11-12-2021
Max I tested both iacvs. There was absolutely no difference in either operation. Both rotated what looked like the same amount of revolutions. As far as mixing the parts and installing the bad, that would have been impossible. I placed a piece of Scotch tape on the old iacv that way I wouldn't that
Titus 2:13
2013 HONDA CB1100
You can hear the iacv operate upon turning the key. Again both iacvs making the same fluttering sound
Titus 2:13
2013 HONDA CB1100
RE: Really high idle - max - 11-13-2021
Thanks Gordo, have a look at this video, i recorded the iacv sound on my cb1100.
What i hear is the iacv opening, then hitting the endstop and then closing a few steps.
Just to compare with your engine.
https://www.youtube.com/watch?v=2Hwhg6qFBSE
If the iacv had an open connection the ecu would detect that in the startup sequence and light the orange cel warning.
That seems not the case so the iacv is connected as it should.
The tps itself has not been reported faulty in the time i have been on this forum, we just wanted to eliminate this when we first started to diagnose this problem and we did eliminate it 100%.
The tps is a fancy potentiometer with 3 or 4 wipers in parallel which is a reliable design and is mounted with it's internal spring loaded shaft acting against the butterfly shaft of the throttle body, the spring ensures the position is the same every time and in sync with the throttle body shaft.
So if your iacv produces the same sound ( with the fuel relay removed ) it is time to consider the newer iacv with the " 31 " part number.
This is a mystery to me as it must be for you but there is always the first time, hope this helps you.
RE: Really high idle - SportsterDoc - 11-13-2021
Max, I was thinking that if TPS output voltage at idle is low, it might be possible the ECU would not completely close the throttle. Just a thought and easy to check the voltage before getting into more complicated procedures.
RE: Really high idle - max - 11-13-2021
Doc you are correct, which is why you suggested this, i came up with a more precise description on how to do this test and it is still worth doing.
In this case i also remembered the case of the mis-aligned pin in the tps connector and brought it up as a possibility.
However if Gordo states" It started immediately at 1500rpms and creeped into the the 1700 rpms as the motor heated up. " ( post# 74 )
As opposed to:
" For giggles I unplugged just the iacv and fired up the bike and it was straight up 1750 rpms, just as it was with the iacv plugged in. Then I unplugged the plug on the left side on the penlum marked Keihen and that brought it down to the 1050 rpms. " ( post#70 )
I am just interpreting this as -and left the iacv unplugged when i disconnected the tps connector--
Which means;
1 the iacv did not move. ( disabled )
2 the engine ecu made a decision.
3 the tps was involved and the cause of this decision ( ecu strategy )
4 the tps appears to have been connected according to the ecu.
So short of Gordo confirming his iacv acts as in the video i made of the iacv moving in post # 107 and checking the tps voltage we are in iacv with new part number replacement territory.
Hope i interpret this correctly by collating all the replies and nobody gets frustrated by the lack of progress.
RE: Really high idle - dave - 11-13-2021
So if your iacv produces the same sound ( with the fuel relay removed ) it is time to consider the newer iacv with the " 31 " part number.
Max, you're a genius! Loved your video. What do you do for a living? Did you mean to say what you did in your above statement? I thought the IACV in your video was functioning correctly. I have never heard the sound of the IACV reaching the end of its travel on my bike, but I have never listened to it with the fuel pump relay disconnected. But then again, I have bad hearing and I just might not be able to hear it.
I apologize if this question has been address previously, but could a faulty Oxygen sensor cause a bad signal to be delivered to the IACV?
Is it possible for Gordon to remove the ECU from his bike and have it inspected?