Hesitation and rough idling with rise in engine temperature

Tiny
CHIBEZEOTI
  • MEMBER
  • 2000 TOYOTA CAMRY
  • 2.2L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 241,276 MILES
My car runs and idles normal when the engine temperature is low, with or without A/C, but starts idling rough and hesitating once the temperature goes up, with or without A/C as well. But it's very severe with the A/C on. The rough idling is consistent once it starts.

I've changed cold starting switch, mass airflow sensor, idle air control valve, intake air temperature sensor (airflow meter), plugs, high tension wires, oxygen sensor (the previous owner of the vehicle had the second oxygen sensor underneath the car removed and sealed), throttle body, fuel pump.
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Friday, April 23rd, 2021 AT 3:31 AM

5 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

Wow, you have already done a lot. Can you tell me if the check engine light is staying on when the engine is running? Also, is there any smoke or odd smells from the exhaust? Have you checked for engine vacuum leaks?

Let me know. Also, here is a link that shows how to check for engine vacuum leaks. Check to see if you can find any issues with a leak.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Let me know. Also, let me know if anything you can think of that may help me diagnose the issue. For example, is there anything that seems to stop the issue? Is there anything that makes it better or less noticeable?

Let me know.

Joe
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Friday, April 23rd, 2021 AT 6:55 PM
Tiny
CHIBEZEOTI
  • MEMBER
Thanks for your reply, much appreciated. Sorry mine's coming late.

The check engine light is always on. It goes off whenever I remove the battery terminals and comes back on after sometime. There's no smoke, but there is an odd smell from the exhaust that I can't describe.

I had the car scanned with an OBDII scanner and it showed a P0401 error. I haven't checked out the EGR valve yet to know if it is bad and needs replacement or not. This is where I am at the moment.

I haven't checked for vacuum leaks yet, would love to do that, but not so sure I can successfully carry out the tests by myself, after reading through the link you provided in your previous post. The problem only seems to stop whenever the engine is cool. Another thing I forgot to tell you, I think the problem affects the fuel efficiency of the car as the car consumes more fuel than required.

Please do let me know if any other thing comes to mind regarding this issue.

Thanks a lot.
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Wednesday, April 28th, 2021 AT 1:46 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Interesting that the problem stops when the engine is cool. Under cold conditions, the EGR is shut down. So, it doesn't necessarily sound like the EGR is bad or sticking. I honestly suspect a vacuum leak. I could be wrong, but that is my first suspect.

If you look below, I included the diagnostics for a P0401. They are extensive. Take a look through them and let me know if it is something you are comfortable doing.

Let me know.

Joe

See pics below.
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Wednesday, April 28th, 2021 AT 5:41 PM
Tiny
CHIBEZEOTI
  • MEMBER
Hi JACOBANDNICKOLAS,

Thanks once again for your reply and the images you sent, they were super helpful and informative.

Before this last message you sent, I noticed that the vacuum hose connected to the Q port of the EGR modulator was hanging loose, but because I didn't know where to connect it, I left it like that. But after seeing the schematic diagram of the EGR valve connections in one of the pictures you sent, I discovered that the hose was to be plugged into the VSV, so I plugged it back in. Also, I removed the EGR valve to check it's condition, it was still working, but had a lot of carbon deposits, so I cleaned it up and installed it back in.

I did all these last night, so I'm yet to test it out. I will go ahead and test it today and get right back to you.

Thank you so much, you've been of immense help to me, I really appreciate.

Best regards.
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Saturday, May 1st, 2021 AT 1:18 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

First, you are very welcome, and thanks for the update. Let me know how things turn out for you. I'm interested in knowing.

Take care,

Joe
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Saturday, May 1st, 2021 AT 7:45 PM

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