Number 8 cylinder throws code P308, and has a knocking sound now...

Asked by Apr 06, 2017 at 09:08 AM about the 2001 Jeep Grand Cherokee Laredo 4WD

Question type: Maintenance & Repair

Had some one "repairing" our 2001 jeep Laredo, but when it
was returned there was a knocking sound from the engine.
What could be causing this and how do I fix it?

4 Answers

113,565

Copy and paste the below

113,565

https://www.obd-codes.com/p0308

880

Code P308 means misfire on cylinder #8. On this 4.7 V8 it would be one of the two cylinders in the back by the firewall...not sure which side. If you are lucky it may be a loose plug wire or bad spark plug. Next you may want to test compression to see if it is a valve or piston problem. I hope it is something simple. Usually it is.

2 of 2 people found this helpful.
160

Hopefully it's not a valve seat come loose in the head. Hornet has the correct procedures for the process of elimination. But, in the 4.7 this is not a good trend. I'm guessing the mileage is very high too. The 4.7 hates to be overheated. Also noted for lifter problems at high mileage. They are prone to rolling a rocker out from under the cam at high mileage. Especially for those out there that only change their oil every 7 thousand miles. And then throw in the timing chains. If your at 150 thousand there wasted. Actually not the chains, but the guides and the hydraulic tensioners. Just eliminate things and eventually you'll find the problem. Head gaskets are a big deal on this engine too. If you can do the work yourself your good. If not be prepared to send your life's savings. Hope it works out for you.

Your Answer

Grand Cherokee

Looking for a Used Grand Cherokee in your area?

CarGurus has 3,634 nationwide Grand Cherokee listings starting at $3,213.

Postal Code:

Jeep Grand Cherokee Experts

  • #1
    inuevafreak
    Reputation
    2,150
  • #2
    Tom Demyan
    Reputation
    1,970
  • #3
    thejeepdoctor
    Reputation
    1,960
View All

Related Models For Sale

Used Jeep Cherokee
98 Great Deals out of 7,487 listings starting at $10,950
Used Dodge Durango
170 Great Deals out of 1,116 listings starting at $4,490
Used Ford Explorer
15 Great Deals out of 1,563 listings starting at $3,395
Used Toyota 4Runner
7 Great Deals out of 541 listings starting at $2,254
Used Jeep Wrangler
108 Great Deals out of 2,018 listings starting at $3,995
Used Chevrolet Tahoe
739 listings starting at $3,995
Used Ford F-150
656 Great Deals out of 9,867 listings starting at $2,995
Used Chevrolet Silverado 1500
198 Great Deals out of 10,040 listings starting at $1,779
Used BMW X5
42 Great Deals out of 979 listings starting at $4,500
Used Ford Mustang
13 Great Deals out of 1,078 listings starting at $3,995
Used Honda Accord
73 Great Deals out of 1,152 listings starting at $2,000

Used Cars For Sale

2018 Jeep Grand Cherokee Laredo 4WD For Sale
143 listings starting at $36,888
2017 Jeep Grand Cherokee Laredo 4WD For Sale
11 Great Deals out of 88 listings starting at $28,979
2016 Jeep Grand Cherokee Laredo 4WD For Sale
7 Great Deals out of 59 listings starting at $25,975
2015 Jeep Grand Cherokee Laredo 4WD For Sale
44 listings starting at $21,988
2014 Jeep Grand Cherokee Laredo 4WD For Sale
34 listings starting at $16,998

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.