03-21-2018, 01:38 AM
(03-21-2018, 12:25 AM)pdedse_imp Wrote:(03-21-2018, 12:16 AM)Dave_imp Wrote: Update. I performed a test suggested by Max, and here are the results: I unplugged the connection to the IACV and rode the bike yesterday. The temperature was 58 degrees, and the bike had not been started in 24 hours. The engine started normally, and idled at about 700 RPM initially. I’m not sure if it would have stalled if I allowed it to idle by itself, but I warmed it up for about two minutes by gently blipping the throttle before going for a test ride. I rode about three miles of stop and go on city streets and as the engine temperature rose, so did the idle RPM. It reached a steady, smooth idle of about 950 RPM before I turned it off, and there was no indication that it would stall. I let the bike sit for about one hour before restarting, and then took it for a longer ride that included stop and go, and about three miles on the freeway. The engine was fully warmed up on this ride, and it settled into a nice, smooth 1,000 RPM idle. There was no indication of stalling, and it never dipped below 1,000 RPM when allowed to idle. I do believe I felt a slight loss in power (very slight), but other than that, the bike ran perfectly. The idle was smooth and repeatable at every stop, it never dipped below 1,000 RPM, and the engine never missed a beat. This test was performed under cool conditions, so I don’t know if it would be repeatable under more severe (hotter, more stop and go) conditions.
On another note, my bike has never experienced the increased RPM when in 1st gear, as the clutch is being let out, as described by other members. Probably 90% of the time I wait until I feel the clutch begin to engage before applying any throttle, so I believe I would have noticed this condition if it was present. This new idle condition described by some members is interesting, and I we can find out if our bikes are designed to do this.
With this information does Dave now have "probable cause" that the IACV is the culprit?
Dave ordered a new IACV from his Honda dealer.
The part is backordered, so there may be a delay in receiving the part.
Dave emailed that he is loyal to his dealer and choose to not order on-line and his dealer gave him a price as good as/close to on-line.
A couple weeks ago (post 726) I commented: "Even though the IACV operation is a prime suspect in most of the reported idle issues, there may be (instead of or in addition to) poor electrical connection(s)."
This may have been Max's direction earlier than that, but Max wanted to be sure that all other possibilities were checked, since replacing the IACV will take more labor than the other checks.
The only other step which may be practical to do, waiting for the new part, would be to unbolt the IACV (air box in place), pull it back enough to squirt some silicone lubricant into the area, which may facilitate easier movement (or not?)...the theory being that if it is binding, the IACV may not in itself be defective, but not able to operate properly.
Previously posted:
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
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.
Until Dave advises further, I am trying to make this post a 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 (solved 203 issues) 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.