Come along with Eric O. at SMA as we have a look at the infamous "misfiring" Jeep 4.0. Now many of you in the shops have ran across this before when you have a 4.0 Jeep and the engine light is on and flashing but there is no felt misfire. We all seem to know it needs a Crankshaft Position Sensor, BUT do you know why!? Check out the files captured on the old sensor and the new sensor and let me know your thoughts. -Enjoy!
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49 thoughts on “Jeep 4.0 – flashing engine light but no misfire!?”
  1. Avataaar/Circle Created with python_avatars mhgrabow says:

    Have misfire and occasional stall with no money light. CPS is a mopar. Gona borrow the meter and give this a look. Thanks

  2. Avataaar/Circle Created with python_avatars James Dvorak says:

    not guessing… "intuiting"

  3. Avataaar/Circle Created with python_avatars camaronash says:

    Having worked on Chrysler products for 20 years, it is imperative you use OEM sensors.

  4. Avataaar/Circle Created with python_avatars Eric G says:

    Those Cherokees will run 300k miles no problem. Knew a guy who owned at least a dozen of these for his business years 98-01 and they are a solid suv. Can be a little temperamental and they have their flaws nut the 4wd and tyranny are indestructible and they will last a long time

  5. Avataaar/Circle Created with python_avatars Antonio Claudio Michael says:

    Wow Never seen a Missfire On all 6 cylinders before And the Engine Run Smooth as Butter that is Interesting Defenitly looks like a Crank Sensor Failure good Video as Always Eric O great find on this video @SouthMainAutoRepairLLC

  6. Avataaar/Circle Created with python_avatars SergeDenas says:

    This happens with my 1500 too

  7. Avataaar/Circle Created with python_avatars Nick Malone says:

    That makes zero sense that aftermarket crank sensor shows all the events with cam perfect but screws up the ecm…ohm out and see if difference between aftermarket and oem…but probavly a field effect transistor sensor

  8. Avataaar/Circle Created with python_avatars Jacob Miller says:

    Just had to swap mine, had a no crank no start outta no where. Running great now (:

  9. Avataaar/Circle Created with python_avatars E. L. says:

    My 2017 just flashed under load po300 code, runs and idles smoothly.

  10. Avataaar/Circle Created with python_avatars JohnClark says:

    Weird that body style is a 2000 my WJ is a 2000 and has the new body

  11. Avataaar/Circle Created with python_avatars John Cramer says:

    My 02 wrangler 4.0 had the same problem. Found out that the sensor has a felt pad on it you need to mash it into the flywheel and it wipes the felt off. The oem came with instalation instructions saying to do it, reinstalled the aftermarket one mashing it in and worked perfectly, couldn't find anything anywhere online to help.

  12. Avataaar/Circle Created with python_avatars Billy Bergstrom says:

    I have a 96 Cherokee cam and crank not in sink how do you resink them can not figure it out have taken it to two shops

  13. Avataaar/Circle Created with python_avatars Edman says:

    I can't get the factory crank sensor for my 95 Grand Cherokee. Went to the dealer and they said they don't make them any longer. I have to use aftermarket.

  14. Avataaar/Circle Created with python_avatars Billy Longley says:

    Had a no fire issue with a dodge Dakota took a guess and changed cps. It fired right up lol

  15. Avataaar/Circle Created with python_avatars Mark Steele says:

    "Rag on the bolt trick" Why didn't I think of that!

  16. Avataaar/Circle Created with python_avatars John E. Carr says:

    Another great video.

  17. Avataaar/Circle Created with python_avatars ALEX says:

    God I wish you were not 14 hrs away lol. I've got the exact opposite issue . Felt misfire with no codes. Once I got a c.e.l but no stored code .

  18. Avataaar/Circle Created with python_avatars Ford Resurrectionest says:

    Sounds like early signs of sensor failure.

  19. Avataaar/Circle Created with python_avatars Os mtz19 says:

    Very interesting 👌🏻
    Quick question 🤔
    2015 Tahoe same blinking engine light, but only on bumpy roads. I hooked up the code readers and there is nothing there. Could this be the same sensor going bad?

  20. Avataaar/Circle Created with python_avatars Jim Vet says:

    awesome job boss…………. Blessed in the LORD.

  21. Avataaar/Circle Created with python_avatars Roy Quesada says:

    Clk..clk…exact torque! 😆🤣

  22. Avataaar/Circle Created with python_avatars Ronald Bergeron says:

    Great video. Could a intermittent crankshaft cause this symptom? Not open, not weak but intermittent.

  23. Avataaar/Circle Created with python_avatars Richard Ward says:

    good job

  24. Avataaar/Circle Created with python_avatars ALBERT ANDERSON says:

    Misfire is speed of the crank not missing or disorted teeth so you should be watching the speed of the crank between spark events to see it on the scope

  25. Avataaar/Circle Created with python_avatars getoffthephone says:

    man guta tell u glad I dont work on cars

  26. Avataaar/Circle Created with python_avatars Mineo Ichokwan says:

    Engine light on with a long Crank 96 jeep Cherokee

  27. Avataaar/Circle Created with python_avatars Eduardo Montanez says:

    Did u have to do a crank sensor relearn ? !

  28. Avataaar/Circle Created with python_avatars kyle parker says:

    I'm showing cylinder 3 and 4 misfire on my TJ .could this be my problem because it absolutely runs perfect. I have 2 different shops look at it and can't find anything wrong

  29. Avataaar/Circle Created with python_avatars Shane Harrison says:

    Yes and it is quiet riot from feel the noise

  30. Avataaar/Circle Created with python_avatars Larry Ehrlich says:

    It's an educated guess…not a plain guess.

  31. Avataaar/Circle Created with python_avatars Lowell Stokes says:

    I have a 1998 with 205k miles, runs great but I’m having this same issue after complete tune, hopefully this will solve the “misfire” issue! Thanks for the info!

  32. Avataaar/Circle Created with python_avatars Foofy M says:

    Got a weird issue, getting a misfire while driving but no light. Unplugged the TPS and it runs just fine. Replaced TPS still have the issue 06 TJ wrangler 4.0

  33. Avataaar/Circle Created with python_avatars Tyler Stewart says:

    Currently going through this shit with my Wrangler. Makes me wonder if my cylinders are actually misfiring or if the sensor is just telling the Computer that it is. $110 Ill never see again lol

  34. Avataaar/Circle Created with python_avatars James Washer says:

    I didn't see the attachments. I'd love to run these through some data processing algorithms. Do you still have the files?

  35. Avataaar/Circle Created with python_avatars matt8863 says:

    A bad coolant temp sensor is another sneaky sh** that can cause misfires and a flashing money light.

  36. Avataaar/Circle Created with python_avatars super20dan says:

    very common if aftermarket sensor used on these jeeps

  37. Avataaar/Circle Created with python_avatars 7S POWER says:

    Eric, basically it comes down to OE or OEM vs after market junk crank sensor part.

  38. Avataaar/Circle Created with python_avatars vetman98 says:

    Love your honesty. You gave us an educated guess. Better than I could do

  39. Avataaar/Circle Created with python_avatars Don Vickers says:

    I had 2 jeeps both with the 4.0 and number one part I replaced the most is the crank sensor (6 times)

  40. Avataaar/Circle Created with python_avatars mike kowalski says:

    Loved the video

  41. Avataaar/Circle Created with python_avatars Doug Noal says:

    Crank sensor went out in my 99 cherokee this summer . would crank all day but never fired . i was just guessing that was the problem but it worked .

  42. Avataaar/Circle Created with python_avatars Tom Harrison says:

    Is it possible that the crank and can sensor goes out if sync by a worn out timing chain?

  43. Avataaar/Circle Created with python_avatars Michael West says:

    i have two Chrysler vans and certain parts have to be dealer parts, ie the oxygen sensor. i went through 8 in the sapce of a month (all aftermarket, even one that was made by the oem manufacturer) and all would fail within a few trips. bought one from the dealer and problem solved. this could be just an example why some important engine parts have to be oem

  44. Avataaar/Circle Created with python_avatars Shane Harrison says:

    It's already in your wave forms good and bad

  45. Avataaar/Circle Created with python_avatars Shane Harrison says:

    But definitly a good diagnoses

  46. Avataaar/Circle Created with python_avatars Shane Harrison says:

    That sensor is in phase the other that it came with is out of phase and firing on cylinders already firing at the time they didnt have to

  47. Avataaar/Circle Created with python_avatars Shane Harrison says:

    You not guessing your hypothasizeing. Be thankful you didnt have the miserable one that goes in the bellhouseing behind the head and tucked in tight out of the way.