Idles rough, runs okay when driving?

BRAJ65

MEMBER
2010 MINI COOPER
1.6L
4 CYL
2WD
MANUAL
93,000 MILES

Replaced plugs, coils, PCV diaphragm, both camshaft position sensors, both camshaft position solenoids, air filter and cleaned injectors. Checked codes and got following attached in photo from Obd2 reader. Any suggestions would be great. Thanks in advance. Ed

6 Replies

KEN L

MASTER CERTIFIED MECHANIC
42,883 POSTS

I don't see the image uploaded. This sounds like you have a vacuum leak, please use this guide when the engine is cold only:

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

This guide may help as well:

https://www.2carpros.com/articles/7-common-symptoms-of-a-vacuum-leak-in-your-car-how-to

https://www.2carpros.com/articles/troubleshooting-rough-idle-in-your-cars-engine-7-common-causes-and-how

If it doesn't have a vacuum leak, we should service the throttle body. Check out this guide and the images below to show you how on your car:

https://www.2carpros.com/articles/throttle-actuator-service

Check out the images (below). Please let us know what happens.

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Monday, March 13th, 2023 AT 11:10 AM

BRAJ65

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17 POSTS

Hey Ken. Thanks for the suggestion. I certainly will explore every possibility. I did attach again the results from the scan. Maybe it will give you a little bit more information. Thanks again, Ed.

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Monday, March 13th, 2023 AT 12:03 PM

BRAJ65

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Ken, I briefly read through that first article, and I can say that I have a high degree of vacuum from the valve cover with the oil cap removed and hand in opening. Also, I noticed when replacing the PCV diaphragm that the hose that goes down to the intake manifold had a high degree of oil in it, and there was sooty exhaust around the tailpipe. The car is actually my neighbor’s, but I am going to take it from him since he doesn’t want to entertain the issues. Thanks again. Ed

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Monday, March 13th, 2023 AT 12:09 PM

KEN L

MASTER CERTIFIED MECHANIC
42,883 POSTS

Yep, good find, these cars had a problem with the valve cover PCV system which causes an internal vacuum leak. I would get a new valve cover and then clear the codes, which should fix the problem. Here is how the job is done. Check out the images (below). Please let us know what happens.

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Tuesday, March 14th, 2023 AT 9:27 AM

BRAJ65

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Hey Ken. Thanks for all the help. I certainly can accomplish the above, but wondering if it would be prudent to use a homemade smoke machine to minimize the amount of new parts I put into this car. I know the engine vent hose is also suspicious. In these models but need to remove intake manifold to get to it. I guess I could narrow my search with carb cleaner, leak detection, and possibly that homemade smoke machine that I was going to put together. Again, thanks for the help. I will update as soon as I get started. Thank you. Ed