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

108,185

Copy and paste the below

108,185

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

730

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.
70

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 71,106 nationwide Grand Cherokee listings starting at $995.

ZIP:

Jeep Grand Cherokee Experts

  • #1
    inuevafreak
    Reputation
    2,120
  • #2
    Tom Demyan
    Reputation
    1,890
  • #3
    thejeepdoctor
    Reputation
    1,790
View All

Related Models For Sale

Used Jeep Cherokee
388 Great Deals out of 41,206 listings starting at $1,500
Used Jeep Wrangler
282 Great Deals out of 15,889 listings starting at $2,997
Used Ford Explorer
802 Great Deals out of 62,813 listings starting at $999
Used Toyota 4Runner
256 Great Deals out of 21,577 listings starting at $2,300
Used Dodge Durango
262 Great Deals out of 20,306 listings starting at $999
Used Chevrolet Tahoe
646 Great Deals out of 37,123 listings starting at $1,800
Used Ford F-150
2,146 Great Deals out of 181,741 listings starting at $1,000
Used Chevrolet Silverado 1500
2,163 Great Deals out of 181,075 listings starting at $1,900
Used BMW X5
400 Great Deals out of 12,955 listings starting at $2,495
Used Chevrolet Camaro
416 Great Deals out of 31,629 listings starting at $2,395
Used Ford Mustang
763 Great Deals out of 42,122 listings starting at $1,300

Used Cars For Sale

2018 Jeep Grand Cherokee Laredo 4WD For Sale
1,635 listings starting at $28,904
2017 Jeep Grand Cherokee Laredo 4WD For Sale
11 Great Deals out of 5,253 listings starting at $24,900
2016 Jeep Grand Cherokee Laredo 4WD For Sale
472 listings starting at $26,499
2015 Jeep Grand Cherokee Laredo 4WD For Sale
16 Great Deals out of 779 listings starting at $18,787
2014 Jeep Grand Cherokee Laredo 4WD For Sale
13 Great Deals out of 903 listings starting at $13,688

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.