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2018 Odyssey having 1-3 second acceleration lag from stopped or rolling, on 9-speed transmission

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Discussion starter · #21 ·
dick_freebird said:
There's two complaints with different symptoms in the early
part of this thread. I'll address the "no rev, no go" one, not
the "revs up, no go".

You may be seeing results of mixture error. Fuel trims show
up late on throttle transitions and you "expose" the basic
("no learning") tune. If you open the throttle into a point of
excess lean operation, you may get spark knock. Knock
retard may be "over the top" as a self-protection measure
and pull timing fast, give it back slow. This could be your
"bog and wait".

You'd need a scan tool that will log your advance, O2 sensor,
knock detect & retard, to dope that out.
Click to expand...
What do "fuel trim", "tune", "knock retard", "pull timing fast", "give it back", and "dope" mean in the above?

I indeed have the "no rev, no go" issue.
 
#22 ·
What do "fuel trim", "tune", "knock retard", "pull timing fast", "give it back", and "dope" mean in the above?
Click to expand...
"Tune" is the fuel, air, spark related portion of the data block
inside the ECM/PCM/whatever Honda likes to call their engine
management "brain". There is code and there is data. Many
layers of activity besides the "simple" running of the engine.

"Fuel Trim" is part of one such layer. The ECM continually
(under normal operating conditions) uses O2 sensor feedback
to develop a calibration map, with the goal of keeping steady-
throttle mixture stoichiometric where the catalytic converters
are effective. This map has segments covering RPM and load
ranges. An engine operating problem or a sensor problem
can fill a cell with extreme "adder" ("trim") values and end up
making things worse.

"Knock Retard" is another learning process. Any knock detect
will pull timing instantaneously (knock retard). There may also
be a cumulative "learning" if knock is encountered often, which
results in timing retard being applied beforehand ("knock
learning"). In the interest of safety (and minimizing warranty
exposure) knock retard is applied big and fast, and removed
slowly over time. Similarly learning (what I have seen) is biased
to roll on fast, per event, and be removed much more slowly.

When I had a vehicle that enjoyed aftermarket scan and tune
support, I could observe the FTC (fuel trim cell), the LTFT
(long term fuel trim) for the cell the engine is running in,
the Knock Learn Factor, and know a whole lot about how
healthy (or how needful of help) the engine and its brain,
were. What of this may be available in Honda aftermarket
tools, no idea. Interested in any options.

Now, lean mixture (in fact) can drive both enrichment, and (by
knock events) knock learning. Lean reading sensors can also
drive enrichment, and mechanical noise that is the wrong kind
of crank-synchronous can drive knock retard.

If you have a situation where low-pedal mixture is trimmed up
(which can happen as O2 sensors age, needing more heat than
low-pedal operation provides, especially in winter) you will see
excessive enrichment. Throw in after-start enrichment and cold-IAT
adders, and you can really hose down your mixture when engine
is cold. Unstable cold-idle RPM is another signature of this. Any
pulled timing does not help.

One thing that tends to reset these various "learnings" is the
old "pull the PCM fuses". This can also be why the thing runs
like ass and starts hard right after a battery swap or fail. You
could try it out and see if the lag goes away (for a while).
 
#23 ·
www.odyclub.com

Transmission Survey + 9/10 speed detailed info (One...

NOT REPORTED IN THE SURVEY /\ [9 speed failures: 2] [10 Speed failures: 9] Not trying to beat this into the ground...just trying to be informative to the community and those that might be experiencing issues. Feel like this should've been created back in 2017/18. On top of that there are so...
www.odyclub.com www.odyclub.com

All this info is here explaining why you are getting this behavior from the 9 speed. It’s not new it’s been discussed to death here. Also would love your input I’m on the survey. Thanks.
 
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#25 ·
Does anyone know whether the Honda PCM applies "torque
management" across shifts? That is, deliberately pulling
throttle, timing or both to baby the delicate little transmission
innards while they're trying to grab next gear?

Used to be a big PITA for post-mods tuning, on my car and
the community, because the baked-in ideas of what timing
or what throttle reduction gives you what torque reduction
go right out the window once you start modding. Or pick up
motor impairments.

Big bog across shifts was a signature. I totally redid the
torque reduction vs torque tables and eliminated that "bog"
from mine.
 
#26 ·
Locarno said:
With the 9-speed transmission on I most frequently get a 1-3 second lag on accelerating from a stop early in my driving session, especially when accelerating from 0 after the first complete stop after the first movement forward in drive. I press the pedal down and get no reaction, no rev, for 1-3 second, then it kicks in and works fine. Often this is getting out of the parking lot, or in turning on to the first busy street from a side street.

It might happen once more on the next stop or slow roll. Then for the rest of the driving session, no problems.

This issue isn't enough to get upset about, but it sure is annoying--and potentially dangerous if I'm trying to get out of the way of another car or pull into traffic.

This thread on Reddit seems like the same issue, but I haven't found any matching issue here. There probably is a thread somewhere but I cannot find it. Anyone else have this issue? Any fix?
Click to expand...
We were experiencing the same issues. We have a 2019 Honda Odyssey EXL. I took it into the dealership multiple times. It is still under warranty. They could not figure it out. I took the advice and cleaned the throttlebody, and it affected the throttle position sensor, and directly affected the shifting and hesitation.
So, after cleaning the throttlebody & MAF sensor with the appropriate cleaner:
1 - the transmission shifting issues and hesitation have COMPLETY disappeared. It was a stark, instantaneous change. right after cleaning, the throttlebody and reassembling, the transmission almost shifted erratically for a few miles and then quickly re-learned. Now, the hesitation, peeling out, and shifting issues are gone. But, then it idled really rough. I had to get the appropriate scan tool to reset the idle. Now, the van is running like it did when I was new! Thank you all for your help!
 
#28 ·
fuego said:
diy? Or this get done at the dealer?
Click to expand...
DIY. It seemed like a pretty simple procedure. I’m a “weekend” mechanic - not a pro by any means. Honestly, I don’t have a lot of faith in the dealer in my area right now. But, you do have to either buy the appropriate scanner to reset the throttle learning system, or go to a mechanic and they’ll do it for around 60 bucks or so. At least around here. Let me know how it goes. We’re few thousand miles in now, and we have literally had no hesitation since.
I wonder if the software on this transmission is so sensitive the ANY LITTLE THING being off causes problems (hesitation etc). Or, if this problem is always caused by the dirty throttlebody?? Not totally sure, but I know it definitely fixed mine. Saved me from trying to sell the car and take a loss.
 
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