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-   -   Hemi shudder gone! (http://www.jeepgarage.org/f181/hemi-shudder-gone-67569.html)

topat46 11-05-2013 09:39 AM

Hemi shudder gone!
 
Hemi shudder gone.
To make a long story short, I had the Hemi shudder. Changed the spark plugs. Shudder 99% gone.
I purchased my 2010 Grand Cherokee Limited in march of this year. It had 32,000 miles on it. It had some quirks with the engine. It felt like I was going over a rumble strip during the interchange of the MDS. I took it back to the dealer and had it checked out but they found nothing wrong. I decided at 39,000 miles (Friday 11/1) to change out the spark plugs knowing that 30,000 miles is the suggested change out time. Guess what?!! The Hemi shudder virtually gone. It only appears very slightly for a brief moment sometimes when accelerating from economy to 8 cylinders. I also used to get when accelerating from a stop and going to about 40mph a feeling that you get when the transmission is in the wrong gear and would only go away when I gave it more gas. This is gone also. Just passing along my experience with this

brentwoodkris 11-06-2013 10:07 AM

Re: Hemi shudder gone!
 
Quote:

Originally Posted by topat46 (Post 924321)
Hemi shudder gone.
To make a long story short, I had the Hemi shudder. Changed the spark plugs. Shudder 99% gone.
I purchased my 2010 Grand Cherokee Limited in march of this year. It had 32,000 miles on it. It had some quirks with the engine. It felt like I was going over a rumble strip during the interchange of the MDS. I took it back to the dealer and had it checked out but they found nothing wrong. I decided at 39,000 miles (Friday 11/1) to change out the spark plugs knowing that 30,000 miles is the suggested change out time. Guess what?!! The Hemi shudder virtually gone. It only appears very slightly for a brief moment sometimes when accelerating from economy to 8 cylinders. I also used to get when accelerating from a stop and going to about 40mph a feeling that you get when the transmission is in the wrong gear and would only go away when I gave it more gas. This is gone also. Just passing along my experience with this

Your plugs must have been pretty bad to make that much of a difference. I'm past my 30k interval and haven't had a noticeable change in performance between new and now. That plus I'm not looking forward to changing 16 plugs.

topat46 11-06-2013 10:17 AM

Re: Hemi shudder gone!
 
To the contrary, they were very good. Only thing I could see was the gaps were at .044. I replaced them with OEM plugs and set them at the .040 gap.

brentwoodkris 11-06-2013 10:35 AM

Re: Hemi shudder gone!
 
Quote:

Originally Posted by topat46 (Post 924980)
To the contrary, they were very good. Only thing I could see was the gaps were at .044. I replaced them with OEM plugs and set them at the .040 gap.

Interesting...but then again, I've never had a "hemi shudder" either.

SteelBlueWK 11-07-2013 10:57 AM

Re: Hemi shudder gone!
 
Quote:

Originally Posted by topat46 (Post 924980)
To the contrary, they were very good. Only thing I could see was the gaps were at .044. I replaced them with OEM plugs and set them at the .040 gap.

The correct factory gap is (0.043 in [1.09 mm]. Some plugs come pre-gapped at 0.044.

topat46 11-07-2013 03:33 PM

Re: Hemi shudder gone!
 
For the 2009 & 2010 Hemi the spec for this plug is as follows:

5.7 V8 Hemi (2009-2010)
Mopar p/n SPLZFR5C11G (NGK)
(.040 gap, 16 plugs, tighten to 13 ft. lbs.*)

I follow all of the information on this site for my Jeep.

SteelBlueWK 11-07-2013 09:18 PM

Re: Hemi shudder gone!
 
You sparked my interest (pun intended) because I have not come across different gap requirements for different model years while reading here in JG. So I did some research and did find some other references and a web page link: Jeep Grand Cherokee WK - Spark plugs

And found out you are correct, sir! I learned something new today. Good to know the new plugs and correct gap fixed your shudder issue.

topat46 11-08-2013 07:08 AM

Re: Hemi shudder gone!
 
Yes there is a difference in the spark plug gapping in specific year Hemi engines. There is also a difference in the horse power ratings. The 2010 engine puts out 357HP while the earlier ones put out 330HP. I don't know what the internal differences are. The Jeep site you mention is actually the place I get most of my information from.

Gojeep 11-09-2013 03:07 AM

Re: Hemi shudder gone!
 
2009 is when they added the VCT, or Variable Cam Timing, and why the hp went up.

topat46 11-09-2013 10:02 AM

Re: Hemi shudder gone!
 
That's good to know. I think the newer 5.7 Hemi is rated at 360HP. I also have a 2004 Grand Cherokee Limited with the 4.7 V8. The weight differences in the 2013, 2010 and the 2004 (if I am reading the specs correctly) are amazing. They jump over 300 pounds in each model style. One of the reasons I opted not to get anything newer than the 2010 was the feeling (to me) that it was clumsy. The 2004 is actually much more maneuverable than the 2010. The 2010 has a much better ride though.


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