03 jeep liberty help

John Fuller

John Fuller

XJ Fanatic!!
Banned
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Jan 3, 2015
Location
Boone NC
hey guys...i'm furious as can be so here it goes.. have a 03 Jeep liberty 3.7 auto misfires with Random Multiple Misfire codes and 3 other codes for individual cylinders. not too uncommon so i start checking the basics (plugs and coils) plugs good and coils....well here's the kicker that has me stumped #3 and #4 coils aren't firing but no power to the coils..switching coils doesn't do anything..unplugging them only changes in other 4 cylinders but not those 2 so anyone with these liberty 3.7 experience this "no power to only couple coils" symptoms. Thoughts? ideas would be awesome and very much appreaciated. thank you

on side note: is the reason why no power to those 2coils is because i happen to be checking them at that time when the mis is on those 2 cylinders but maybe i should let it run longer and see if it changes power to other ones. SORRY BEEN LONG DAY if i'm confusing anyone and probably tired too but hate to go to bed unsolved,lol. my brain is either failing me LOL or i'm overlooking something simple here thank you
 
only other info i have is that on my "fairly basic" scanner, the ST FTRIM and LT FTRIM values are 0 the whole time running...one time bank 1 LT FTRIM was -24 and climbing but then went back to 0 stayed there for the 5 minutes or so i had it running during that time if this helps anyone out in pinpointing any ideas.
 
yeah i've wiggled about everything while running and no change...i think i might have to send this customer to someone with big scanner software where they can watch live data of all the sensors and voltage readings which i'm sure wouldn't be much for that system to catch..
just so i learn a little...the fuel trims i know change but they shouldn't just stay at 0 right..i've heard they should be around positive 3or4 on normal running engine..
 
Use a noid light to monitor the injectors pulsing. Wiggle the connector while watching the light, the harness tends to fatigue and break wire strands right behind the connector body.
 
will do that in the am. i had to move onto other jeeps today so i wouldn't loose my mind over it and tomorrow hit it up fresh in the morning. thanks
 
Sounds like it's switching open/closed loop for sure! You should fall back to the diagram and determine what's wrong at the coils in my opinion if their not firing (not sure if I read that right). I just use the scope and ramp them, if no ramp I look for what that coil design uses (power ground and signal etc.)
I find what's missing and fix it. I've seen my fair share of ecm coil drivers bite the dust. With a ltft maxing like that it sounds like you have an ignition issue imo . If you need to run it over I'm always at the shop with the exception of the 1-2 lunch hour.
 
well hey dude..what shop? this is good to know for this jeep and others that run beyond my level of knowledge to diagnose (this being my weakness usually on other cars) so yeah it would be nice to know who this is so i can meet and hope to send you some work instead of sending it to some random shop for special diagnostics. thanks dude
 
oh cool i will have to stop in and see you one day. i just figured it out and motor took a crap...pulled drivers side valve cover and holy crap..4 rocker arms were dislodged..3 cam bearings broke off..so needless to say motor is no good..i can't believe it was even running with only one cylinder on that side firing. i guess we're going to part it out since rebuild is way too much..1147 just in parts for everything new heads, timing and gaskets WHEW that's high..thanks for your input and will stop in one day.
 
If they decide to sell it with blown motor i maybe interested
 
they are...new tires, and 2 weeks ago New Rotor and Pads all the way around, new rear driveshaft, Transmission is perfect which has been serviced as should be, interior seats/sunroof/headliner/carpet very clean, body very clean no rust drove great until this, alternator is newer, no a/c just bypass pulley...Call me John 828 964 3128 going back out to shop so call if you need more details and stuff. thanks and make offer from what i've stated.
 
check the doubler, it may not be shifting correctly
 
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