1. Home
  2. General Toyota Forum
  3. Rough Idle problem

Rough Idle problem

Hi,

I recently replaced the catalytic converter because the check engine light would come on with P420 (catalyst efficiency below threshold (bank 1)). I watched the O2 sensors with some software and they had similar outputs which made me feel its the converter. After the change the back one is very different than the front one so it seems that the new converter is working much better than the old one.

Problem is that after the car warms up, when sitting at a stop sign pressing the break there is a very bad vibration which I interpret as a rough idle. If I switch to neutral or park, it goes away. It also seems to happen when I go very slowly (almost without pushing the gas pedal) in reverse. Other than that the car seems to run fine.

The car ran fine before I changed the converter.... The new converter is a that Catco. My car is a '96 Toyota tercel with 105K miles on it.

Does anyone know why this started happening?

Thanks much! Mihaela

Reply to
Mihaela Mihaylova
Loading thread data ...

You did not mention another malfunction indicator light (check engine light) so the first thing to check is idle speed with the transmission engaged and compare it with the factory spec.

Check the plastic intake tube between the air filter and throttle body for cracks or leaks.

If idle speed is low, check the idle air control valve.

Reply to
Ray O

ok thanks much for the reply. Yeah there are no other codes and the check engine light is off. I will follow your advice in a couple of weeks. I reset the computer this morning so that it tries to re-learn the idle as I don't think that we reset it after we changed the converter (I had cleared the MIL a week or so before the repair).

Thanks again! Mihaela

Reply to
Mihaela Mihaylova

Also, check for vacuum leaks.

Good luck!

Reply to
Ray O

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.