1. Welcome to Jeeps.net!

    You are currently viewing as a guest! To get full-access, you need to register for a FREE account.

    As a registered member, you’ll be able to:
    • Participate in all Jeep discussion topics
    • Transfer over your build thread from a different forum to this one
    • Communicate privately with other Jeep owners from around the world
    • Post your own photos in our Members Gallery
    • Access all special features of the site

4.0 misfiring

Discussion in 'General Jeep Discussion' started by fishtale77, Sep 21, 2016.

  1. Sep 21, 2016 at 10:05 AM
    #1
    fishtale77

    fishtale77 [OP] Member

    Joined:
    Sep 21, 2016
    Member:
    #247
    Messages:
    11
    Gender:
    Male
    First Name:
    fishtale
    Vehicle:
    01 grand cherokee 4.0
    I have a Grand Cherokee 2001 4.0 with 165000 miles. While it is idling the gauge is jumping and there is a thumping noise. The code says the timing chain is stretched or not working. what kind of price am I looking at to have it repaired. Thanks for any info
     
  2. Sep 21, 2016 at 12:13 PM
    #2
    C2T

    C2T Well-Known Member

    Joined:
    Jul 31, 2016
    Member:
    #42
    Messages:
    759
    Gender:
    Male
    First Name:
    Richard
    Helena, Montana
    Vehicle:
    Jeep
    2.5" AEV Dual Sport lift, 35" Treadwright Guard Dogs, Black Rock Wheels, AEV Front & Rear Bumpers with Tire Carrier, Fuel Caddy 10 gal. Aux. fuel tank, Warn 9.5ti, 125' synthetic winch line, front axle skid, 20" LED light bar , Bilstein Shocks, steel steering skidplate,
    I would anticipate a bill for about 4 to 5 hours from your local mechanic, though it can and will vary. Parts are cheap enough @ <$100.00.

    My local Jeep dealer's wrench turners bill out at about $100/hr. and non-dealer mechanics are often about $65/hr to 75/hr. So I would estimate between $400 and $600 if that is all that is wrong with it.

    It is not a hard job if you have a garage and the correct tools...but it does take some time.

    I hope this information helps. Good Luck!!
     
  3. Sep 21, 2016 at 12:13 PM
    #3
    C2T

    C2T Well-Known Member

    Joined:
    Jul 31, 2016
    Member:
    #42
    Messages:
    759
    Gender:
    Male
    First Name:
    Richard
    Helena, Montana
    Vehicle:
    Jeep
    2.5" AEV Dual Sport lift, 35" Treadwright Guard Dogs, Black Rock Wheels, AEV Front & Rear Bumpers with Tire Carrier, Fuel Caddy 10 gal. Aux. fuel tank, Warn 9.5ti, 125' synthetic winch line, front axle skid, 20" LED light bar , Bilstein Shocks, steel steering skidplate,
    oh...and welcome to the forum. :)
     
  4. Sep 21, 2016 at 1:03 PM
    #4
    fishtale77

    fishtale77 [OP] Member

    Joined:
    Sep 21, 2016
    Member:
    #247
    Messages:
    11
    Gender:
    Male
    First Name:
    fishtale
    Vehicle:
    01 grand cherokee 4.0
    Hey thanks. That gives me an idea of the cost.
     
  5. Sep 21, 2016 at 1:11 PM
    #5
    C2T

    C2T Well-Known Member

    Joined:
    Jul 31, 2016
    Member:
    #42
    Messages:
    759
    Gender:
    Male
    First Name:
    Richard
    Helena, Montana
    Vehicle:
    Jeep
    2.5" AEV Dual Sport lift, 35" Treadwright Guard Dogs, Black Rock Wheels, AEV Front & Rear Bumpers with Tire Carrier, Fuel Caddy 10 gal. Aux. fuel tank, Warn 9.5ti, 125' synthetic winch line, front axle skid, 20" LED light bar , Bilstein Shocks, steel steering skidplate,
    No problem. Take it all with a grain of salt though....I don't claim to be an expert and it can change a good deal from place to place.

    :)
     
  6. Sep 21, 2016 at 1:40 PM
    #6
    fishtale77

    fishtale77 [OP] Member

    Joined:
    Sep 21, 2016
    Member:
    #247
    Messages:
    11
    Gender:
    Male
    First Name:
    fishtale
    Vehicle:
    01 grand cherokee 4.0
    Does anyone have any suggestions on what else i should have done while the mechanic has the motor open? Thanks
     
  7. Sep 21, 2016 at 2:10 PM
    #7
    C2T

    C2T Well-Known Member

    Joined:
    Jul 31, 2016
    Member:
    #42
    Messages:
    759
    Gender:
    Male
    First Name:
    Richard
    Helena, Montana
    Vehicle:
    Jeep
    2.5" AEV Dual Sport lift, 35" Treadwright Guard Dogs, Black Rock Wheels, AEV Front & Rear Bumpers with Tire Carrier, Fuel Caddy 10 gal. Aux. fuel tank, Warn 9.5ti, 125' synthetic winch line, front axle skid, 20" LED light bar , Bilstein Shocks, steel steering skidplate,
    Well, it is a great time to replace your fan belt and if your water pump is having issues, he has to remove that to get to the timing chain anyway so it won't cost much more than the pump itself. Other than that, the mechanic will likely give it the once over when he starts working on it.

    :)
     
    VOZ likes this.
  8. Oct 6, 2016 at 4:52 AM
    #8
    fishtale77

    fishtale77 [OP] Member

    Joined:
    Sep 21, 2016
    Member:
    #247
    Messages:
    11
    Gender:
    Male
    First Name:
    fishtale
    Vehicle:
    01 grand cherokee 4.0
    Well the shop says its not the timing chain. I changed the plugs and it fixed the missfire for about a week. Then it came back. Then they changed the crank shaft position sensor. That fixed the problem for about a week also. Then yesterday it started worse than before. Now i cant even drive it cause its missfiring so bad. I checked the plugs and one was real black with soot.someone suggested to change the 2 o2 sensors on the exhaust. Any suggestions on what else to try. Thanks
     
  9. Oct 6, 2016 at 8:44 AM
    #9
    C2T

    C2T Well-Known Member

    Joined:
    Jul 31, 2016
    Member:
    #42
    Messages:
    759
    Gender:
    Male
    First Name:
    Richard
    Helena, Montana
    Vehicle:
    Jeep
    2.5" AEV Dual Sport lift, 35" Treadwright Guard Dogs, Black Rock Wheels, AEV Front & Rear Bumpers with Tire Carrier, Fuel Caddy 10 gal. Aux. fuel tank, Warn 9.5ti, 125' synthetic winch line, front axle skid, 20" LED light bar , Bilstein Shocks, steel steering skidplate,
    On the cylinder that was all black...you might try checking/changing the injector. Just did that on a TJ last weekend over misfiring and power problems. A new injector fixed that one. A compression test might be called for too.
     
  10. Oct 6, 2016 at 8:29 PM
    #10
    OFFGRID

    OFFGRID Well-Known Member

    Joined:
    Oct 3, 2016
    Member:
    #317
    Messages:
    1,843
    Gender:
    Male
    First Name:
    Peter
    Houston
    Vehicle:
    1979 Jeep CJ7, 258, TH350, NP208
    Howell fuel injection, header, HEI distributor, TH350, NP208, SOA lift with YJ springs in the front & GW springs in the Rear. AMC20 with G2 1 piece chromos trussed, Dana 30 with G2 chromos and 760x ujoints and MM Stainless Hubs, Geared 4.56. Tom Woods shafts, Metal cloaks, Caged, 37" Toyo MTs.
    do you have coil packs or distributor in your jeep. Sounds electrical to me. Could be a spark plug wire or wires grounding out. Coil packs may be going bad. The one plug that is all black, is it getting spark. Here is a link to test for spark.

    https://www.youtube.com/watch?v=VnfcMSKskjY
     
  11. Oct 13, 2016 at 3:28 PM
    #11
    fishtale77

    fishtale77 [OP] Member

    Joined:
    Sep 21, 2016
    Member:
    #247
    Messages:
    11
    Gender:
    Male
    First Name:
    fishtale
    Vehicle:
    01 grand cherokee 4.0
    The coil packs are new. Plugs new. Camshaft sensor new. Pigtail Plug to that sensor is new. I might change the o2 sensor for that cylinder.im guessing the upstreem one. There are 4. And about 50 bucks each
     
  12. Oct 13, 2016 at 3:29 PM
    #12
    fishtale77

    fishtale77 [OP] Member

    Joined:
    Sep 21, 2016
    Member:
    #247
    Messages:
    11
    Gender:
    Male
    First Name:
    fishtale
    Vehicle:
    01 grand cherokee 4.0
    And i think it only missfires when the temp gauge gets to just under halfway.
     
  13. Oct 13, 2016 at 4:06 PM
    #13
    C2T

    C2T Well-Known Member

    Joined:
    Jul 31, 2016
    Member:
    #42
    Messages:
    759
    Gender:
    Male
    First Name:
    Richard
    Helena, Montana
    Vehicle:
    Jeep
    2.5" AEV Dual Sport lift, 35" Treadwright Guard Dogs, Black Rock Wheels, AEV Front & Rear Bumpers with Tire Carrier, Fuel Caddy 10 gal. Aux. fuel tank, Warn 9.5ti, 125' synthetic winch line, front axle skid, 20" LED light bar , Bilstein Shocks, steel steering skidplate,
    Possibly silly questions...did you check your coolant temp sensor? When those go bad they cause the system to run really poorly...including misfiring. A thought....
     
  14. Oct 15, 2016 at 10:42 AM
    #14
    fishtale77

    fishtale77 [OP] Member

    Joined:
    Sep 21, 2016
    Member:
    #247
    Messages:
    11
    Gender:
    Male
    First Name:
    fishtale
    Vehicle:
    01 grand cherokee 4.0
    Thats a good idea. The other day it was running too hot. So i changed the thermostat. Seems to have fixed that. Ill try the temp sensor
     
    C2T likes this.
  15. Oct 15, 2016 at 3:40 PM
    #15
    fishtale77

    fishtale77 [OP] Member

    Joined:
    Sep 21, 2016
    Member:
    #247
    Messages:
    11
    Gender:
    Male
    First Name:
    fishtale
    Vehicle:
    01 grand cherokee 4.0
    Nope. Wasnt the temp sensor. Put a new one in
     
  16. Oct 15, 2016 at 4:02 PM
    #16
    C2T

    C2T Well-Known Member

    Joined:
    Jul 31, 2016
    Member:
    #42
    Messages:
    759
    Gender:
    Male
    First Name:
    Richard
    Helena, Montana
    Vehicle:
    Jeep
    2.5" AEV Dual Sport lift, 35" Treadwright Guard Dogs, Black Rock Wheels, AEV Front & Rear Bumpers with Tire Carrier, Fuel Caddy 10 gal. Aux. fuel tank, Warn 9.5ti, 125' synthetic winch line, front axle skid, 20" LED light bar , Bilstein Shocks, steel steering skidplate,
    Damn! and that was my best last WAG too.
     
  17. Oct 15, 2016 at 9:18 PM
    #17
    OFFGRID

    OFFGRID Well-Known Member

    Joined:
    Oct 3, 2016
    Member:
    #317
    Messages:
    1,843
    Gender:
    Male
    First Name:
    Peter
    Houston
    Vehicle:
    1979 Jeep CJ7, 258, TH350, NP208
    Howell fuel injection, header, HEI distributor, TH350, NP208, SOA lift with YJ springs in the front & GW springs in the Rear. AMC20 with G2 1 piece chromos trussed, Dana 30 with G2 chromos and 760x ujoints and MM Stainless Hubs, Geared 4.56. Tom Woods shafts, Metal cloaks, Caged, 37" Toyo MTs.
    You haven't said if you changed your plug wires, Bad wires will cause symptoms like that. If 1 or more wires are grounding out or not making a good connection the engine will not run well. In case it is not the wires, You said that you have a plug that is black, and you changed the plugs. You found one was black again. Is it black with engine oil and gummy oil residue, or is it dry black soot. What I'm getting at is that if it's been running hot like you said (did it overheat). If it overheated you're opening a whole other can of worms.
     
  18. Oct 16, 2016 at 3:06 AM
    #18
    fishtale77

    fishtale77 [OP] Member

    Joined:
    Sep 21, 2016
    Member:
    #247
    Messages:
    11
    Gender:
    Male
    First Name:
    fishtale
    Vehicle:
    01 grand cherokee 4.0
    Dont have wires. The coil packs r new though. And it didnt over heat. The plug was black with dry soot
     
  19. Oct 16, 2016 at 7:22 AM
    #19
    OFFGRID

    OFFGRID Well-Known Member

    Joined:
    Oct 3, 2016
    Member:
    #317
    Messages:
    1,843
    Gender:
    Male
    First Name:
    Peter
    Houston
    Vehicle:
    1979 Jeep CJ7, 258, TH350, NP208
    Howell fuel injection, header, HEI distributor, TH350, NP208, SOA lift with YJ springs in the front & GW springs in the Rear. AMC20 with G2 1 piece chromos trussed, Dana 30 with G2 chromos and 760x ujoints and MM Stainless Hubs, Geared 4.56. Tom Woods shafts, Metal cloaks, Caged, 37" Toyo MTs.
    Check each wire for a good "TIGHT" connection on each plug, especailly the black plug. You said that it ran fine after installing new plugs then started acting up again. Maybe one of the wires is not getting a good connection. Something electrical sounds like it is wiggling around. I'm just guessing.

    Do you know what the actual code is?
     
  20. Oct 16, 2016 at 7:32 AM
    #20
    OFFGRID

    OFFGRID Well-Known Member

    Joined:
    Oct 3, 2016
    Member:
    #317
    Messages:
    1,843
    Gender:
    Male
    First Name:
    Peter
    Houston
    Vehicle:
    1979 Jeep CJ7, 258, TH350, NP208
    Howell fuel injection, header, HEI distributor, TH350, NP208, SOA lift with YJ springs in the front & GW springs in the Rear. AMC20 with G2 1 piece chromos trussed, Dana 30 with G2 chromos and 760x ujoints and MM Stainless Hubs, Geared 4.56. Tom Woods shafts, Metal cloaks, Caged, 37" Toyo MTs.
    Did a quick little search. This is what I found. "Normally misfires are plugs/boot, carbon build up, or injector/fuel pump problem.", and "I'd start with testing fuel pressure with a fuel pressure gauge at the schrader valve on the fuel rail.

    Troubleshooting is a process of elimination. Have to start with the basics and solid fuel delivery is one of them.

    With a 2001, you're looking for around 49 psi plus or minus 5."
     
To Top