At idle engine shakes a little rough, but it runs without any roughness or missing

ANONYMOUS

MEMBER
1998 NISSAN ALTIMA
160,000 MILES

It does not even miss at idle just the roughness. There is no check engine lights on and I have put a scan tool on car and it has no codes. The car has had new plugs installed(the negative v power plugs) new spark plug wires, air filter, MAF sensor, another fuel rail with fuel injectors. I have sprayed carburetor cleaner all around vacuum hoses and intake manifold to see if engine changes idle to see if there was a leak and the idle did not change. What do I do next to correct this problem?

4 Replies

CADIEMAN

MECHANIC
3,544 POSTS

Do a compression test at this point. You will need to make sure that the motor is good.

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Tuesday, November 20th, 2012 AT 3:55 PM

DAVIDDLW

MEMBER
39 POSTS

I did the test on car and the engine tested great with all 4 cylinders at 140 and 141 psi. I notice when car has been sitting over night the engine will not idle rough until it has warm up. Maybe this bit of info is important to your evaluation. And like I said it is not a bad rough idle just that you know that this may not be normal. And the engine does not throw any codes and do not mis at idle or running.

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Friday, November 23rd, 2012 AT 4:29 PM

CADIEMAN

MECHANIC
3,544 POSTS

You will need to check the vacuum it may be leaking. See if the parts store has one you can use or rent. It's simple to hook it to a vacuum hose then start it up. The gauge will either red or green. This will cause a rough idle.

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Saturday, December 1st, 2012 AT 1:52 AM

ASEMASTER6371

MECHANIC
52,797 POSTS

Good morning,

It could be the mounts but I doubt it very much. If the mounts were worn that much, you would have noises and all kinds of other indications of the power-train moving.

https://www.2carpros.com/articles/how-a-motor-mount-works

https://www.2carpros.com/articles/replace-motor-mounts

https://www.2carpros.com/articles/vibration-noise

My own thoughts are around the injectors. If the spray patterns are off from being clogged or dirty, it will cause this issue.

There are no additives that will work for cleaning the injectors. They need to be cleaned by disabling the fuel system and running the engine on the actual cleaner. That is the only way to clean them correctly.

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

Roy

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Monday, May 18th, 2020 AT 5:00 AM