So the engine of my SS is shaking slightly every now and then at idle. Tough to explain but I can feel it slightly hesitate for like a split second but never dies. This only happens at idle. Drives well otherwise. I recently used 87 for about two tank full due to gas shortage but I have now switched back to premium. I have replaced spark plugs (Iridium) and air filter. I did not replace the ignition coils though but wondering if it makes sense to replace those as well. There is no CEL light at this time. Thanks in advance.

 

No CEL , no sense throwing parts at it! You say iridium plugs, AC Delco 41-108, the OEM plug? Or some other brand?
I’d run Techron fuel treatment for one tankful with the proper octane fuel. It should clear up.

 

Thanks a lot for the very quick reply. Yes I used Set of 4 ACDELCO 41108 Iridium Spark Plugs For Buick Chevy Impala GMC 12620540. I did use Lucas Fuel Injector treatment about two tanks a go and wondering if using the Techron will not hurt anything. Thanks.

 

Might be your front engine mount is worn out.

 

Interesting. I'll have my mechanic check that for me. Just passed inspection though and I think they check the engine mounts but you still never know. Thanks.

 

To check that upper engine mount , simply look in the passenger side front wheel well, in the oblong hole, you should see the serpentine belt tensioner bolt, it should be up in the middle, if it’s lower and appears like you couldn’t get a socket on it, the upper engine mount is toast!

 

A/C on?

 

Yes AC is on at times. However I followed someone's advice here and so far so good. Used a bottle of Techron and the engine is really smooth now. Will keep monitoring. Thanks.

 

Just to thank you for your advice. I bought a bottle of Techron and poured it entirely into a half empty tank. I have been driving it the whole day and the engine idle is once again as smooth as new. OMG!!! Been testing it for the past couple of days and everything seems to be fine. In fact I bought a couple for my other cars. Much appreciated.

 

Did the shake go away when you turned the AC off?