Torque converter vs. catalytic converter

I have a 2007 Honda Pilot with a rebuilt transmission. I am having two problems: 1) car shakes when at a stop in park (sounds like a diesel) and 2) no power in reverse when trying to back up a hill. The mechanic who rebuilt the transmission says its a clogged cat converter. Another mechanic told me it the torque converter. Would be interested in people’s opinion as to what is wrong and what tests can be run to solve problem. Thx D

If it is the cat coverter, that would show up if you had an emissions test done on it. If that comes through clean, go back to the mechanic who did the transmission work, show him the report, and tell him he needs to rethink this.

If it is the Cat converter, you would have the same loss of power in drive as well. The shaking probably means a missfiring engine.

Besides, if the engine is misfiring that badly, the check engine light would DEFINITELY come on.

It is very possible–even likely–that the CEL is lit up, even though the OP did not mention it.
If that is the case, then the OP needs to get the stored trouble codes read at an auto parts store.

Truthfully, I think that there is more than one problem with this vehicle.

The shaking while in Park is almost certainly not related to the torque converter, simply because the torque converter is not engaged when the shift lever is in neutral or park.

However, a problem with the transmission of power when in reverse almost surely points to a transmission problem. It sounds to me like the guy who rebuilt the trans is trying to engage in a delaying tactic until the warranty on the trans runs out.

If the car drives ok in drive, but shakes in park, I really doubt it’s the cat. If all these problems started with the rebuild, it’s that mechanic’s job to get it back running as well as it did before the rebuild.

A vacuum gauge and instructions on how to read it will show a clogged cat.

Your 2007 Honda Pilot monitors both the catalytic converter performance and the transmission function. If there were a problem with either of these systems the Check Engine light would be on.

Is it?


thanks everyone. Just a point of clarification/correction: the car shakes and makes diesel sound when stopped but in Drive (ie foot on brake at stoplight), but not when I put it in Park (noise/shake goes away). There is no check engine light.

the symptoms sound nothing like a clogged cat. And sound very much like a torque converter that is not disengaging properly. I think the tranny mechanic is trying to dodge going back in and redoing the job someone botched.

Then have the exhaust system checked.

In order to replace the transmission the exhaust pipes had to be remove. These exhaust pipes need to flex when torque is applied the the engine. Such as sitting at a stop in gear. If the pipes become out of alignment/leak the engine will get louder like a diesel engine and run rough because there’s less back-pressure.


If the engine is shaking in Drive, I still bet the engine is not running right.

New torque converter when trans was rebuilt?