Posted to Transmission Forum on 12/5/2015
Re: Honda shudder/hesitation issue
There's an ATRA bulletin out about a defective EGR valve
causing a TCC-like shudder sensation at lower speeds. I've
only had one vehicle do it and it felt more like a lean
engine miss to me. The diagnostic procedure is to disconnect
the lines from the EGR valve and see if the problems go
away. I'd provide a copy of the bulletin, but I'm already on
TiNA's bad side.
The Odysseys have a serious problem with cooler/converter
oil flow when hot and in lockup. The oil exiting the
converter is always directed to the cooler. The converter
charge oil (fluid going in) is what applies the TCC. The
pressure difference between the converter charge oil on the
front side of the TCC piston, and oil exiting the converter
on the back side of the TCC piston is what applies the TCC
What ultimately happens is that the flow of ATF in and out
of the converter effectively falls to a trickle (or stops
all together) and causes a low clamping force of the TCC
piston on the converter cover (face). This slip is not
smooth and it's a very quick "slip-grab-slip-grab"
repeatedly like you're driving over a washboard road.
A lean engine miss under load can often duplicate this
feeling and I've seen it misdiagnosed by some really sharp
techs. The reason this takes place is that when they disable
the TCC, the problem seems to go away. What's REALLY
HAPPENING is the lean engine miss is STILL THERE, but you
can't feel it because NOW the converter isn't locked up and
the fluid coupling nature of the torque converter
hydraulically dampens out the lean engine miss to where the
driver can't feel it any more. The miss is STILL THERE. You
just can't feel it because it's being dampened out.
Take it from a transmission man who knows.
Technical Information Specialist/Technician
Draper, Utah, USA
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