[lovemyavy]

Hello everyone. I have a 2000 Toyota Avalon with about 200K miles on it. It's still a great car. Unfortunately, there are some issues and one is that after 15 minutes, it will run rough. It will make a "chugging" sound as soon as 15 minutes have passed from a fresh start. The first time this happened, the front of the cat converter was replaced. That did not fix the issue. When I crank it up, minutes 0-14 run just as smooth as possible. As soon as a 15th minute rolls around, it chugs. On the inside, it feels like it is vibrating. Even when you put it in park, the tachometer starts to rise on its own. I thought it could be the vacuum solenoid and the MAF sensor, so I replaced the MAF with a new one (it runs better in the pre-chug mode now) and I had another solenoid from the junk shop. Neither of those have fixed the issue.

If I turn the engine off unless it goes to essentially a cold state, it will just chug once I turn it back on.

There is also a low-pitched hum that I can hear as soon as I start the car which lets me know it will start chugging. Before all this happened, there was no low-pitched hum.

 

[BMR]

Check the ECT sensor. It sends a coolant temperature signal to the ECU. If it’s bad, the ECU will constantly run the injectors waaay too rich. It’s the one marked “1” in this pic. Pull the connector off and measure resistance across the two terminals on the sensor. It should be about 3000 ohms cold, and 300 warmed up.

This is the passenger side of the motor:

 

[lucidbarrier]

This is the passenger side of the motor:
View attachment 404183

Where can I get a strut tower brace? That looks really clean!

 

[BMR]

That’s not my car/engine. I’ve read that the Solara came with a strut bar that fits.

 

[lovemyavy]

Thanks for this info!

Not sure why I didn't think to get the OBD codes read first, but I did that too. I got P0500 (from the ABS light which I can't figure out what to do about it), P0300 (knock sensor circuit 2 bank 2) and P1354 (valve timing sensor). I think P1354 is what is causing this problem because the other codes are older. If I can figure out where it is, I have read that cleaning it with brake fluid may help.

Check the ECT sensor. It sends a coolant temperature signal to the ECU. If it’s bad, the ECU will constantly run the injectors waaay too rich. It’s the one marked “1” in this pic. Pull the connector off and measure resistance across the two terminals on the sensor. It should be about 3000 ohms cold, and 300 warmed up.

This is the passenger side of the motor:
View attachment 404183