max_imp said:
As you may have read some lucky members have permanently fixed their issue with a software update, not possible in the us, e.p.a. is a scary thing so the dealers are not prepared to risk their business i believe.
Every single cb with this issue ( mostly the 2014 models ) started good as gold but something changed over time and we never saw any wear or dirt in the valve body, so what gives?
And i don't know of any member who did not have success with a new iacv, to me it is the lack of control from the ecu,
( hence the software " update " ) i think the older iacv's permanent magnets have degraded to the point where they no longer control the iacv correctly.
A lot of times this has happened after the engine has been very warm, permanent magnets lose magnetism if the temperature rises, the iacv is in a hot place and that is why i have come to this conclusion.
You may be in a unique position to evaluate the " magnetic torque " difference between an old and a new one firsthand.........
Haya Doc.
Max, your permanent magnet degradation theory is quite plausible.
Perhaps an ECU program compensates for a failing IACV, but that may be just postponing an issue.
The below summary is from post 103, as linked in post 1299 and has been edited only slightly in that debris hindering operation or warpage does not seem to be an issue.
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
position 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.
IACV explained
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 will not provide a DTC 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, so, it may not sound much different. The ECM has no feed-back regarding actual movement.
Whiszzle, pls be sure to review Max's IACV link:
IACV explained
