Hesitation and rough idling with rise in engine temperature

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

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.

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.

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.

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

Dear Joe,

Remember me? Trust you are doing well today. So sorry I haven't gotten back to you since regarding my car challenges, but I am happy to announce to you that those fixes we did actually fixed the problem. I also replaced the VSV switch. Now, the car runs normal and idles well. Thank you so so much, I really appreciate. You've been a great help. You the man Joe.

Best regards,
Chibueze

Hi,

Thank you for letting me know, and you are very welcome. I'm glad to hear you got it fixed. Also, your follow-up will certainly help others.

Please feel free to come back anytime in the future. You are always welcome here.

Take care of yourself,

Joe