Hey folks,

We've run into an issue up here where the 3.6 engine shudders when in park/neutral at between 1500-2000 RPM (with the worst at roughly 1800RPM). My concern is the shake feels like the engine is out of balance. The dealership tested 3 other Impalas with the same behaviour.

It could be a map issue - as the fuel map is different between Park and other gears - but shouldn't that mean Neutral would behave differently?

This is also a shudder that can be experienced at around 118kmph and several other speeds (that I can't remember off the top of my head).

Hoping you guys could check out your cars - the fear is an engine out of balance will eventually have severe issues. Is it worth pushing Chevrolet to look into this further?

Thanks!

 

Why are you revving the engine in neutral or in park?

My car is smooth driving. LuckyDriver has some issue at idle when in gear of the steering wheel shaking. vibration in steering wheel when stopped - Chevy Impala Forums


I'm going to guess you would probably need to get some diagnostic tools on the car and see if timing is being severely retarded.



118 Kilometer/Hour (km/h) = 73.3218 Mile/Hour (mph) for those of us who don't know.

 

Thanks for the reply

So I revved it in park / neutral because I noticed the shudder at several specific RPMs/speeds where the car was driving. 116-122 (most notable), 86-90km/h - both in the troubled RPM range. Diagnostic is fine - both the dealership and I checked - no timing/spark issues, RPM curve is flat, not shaky.

This doesn't affect the steering - you can feel it in the gas pedal and and the body slightly. It's like a faster, gentler version of idle torque shake old chev engines get (big blocks and the like).

You're right - no reason to rev while stationary, but again the fear is it could be a symptom of what could become a larger problem. It feels like an internal balance issue - but would that only be noticeable at specific RPMs?

 

They can perform some engine vibration analysis (see the other forum post)....

I haven't tried to rev mine to 2000 rpm in park..so I don't know what would happen.

 

I have read at GM web site that a few 3.6 motors had bad piston's put into some motors. Some new Impala's had to be tow back to some dealerships cause there motor's refuse to run.Something about the piston's being incorrect in there size when they were put in. Only after a putting on 5000 miles a rough idle appear in the motor would this shake a little.

 

I found a TSB for a 2013 impala...doesn't say 3.6l or 4 cylinder.

2013 was the LLT motor not the LFX.

nhtsa reference: 10053869
tsb reference: #sb-13283

 

this is the best motor power and quiet and very smooth. the engioneering is in this one. regards bumperking

 

Any luck with this issue?