2002 jeep liberty limited 3.7 L. scanner shows bad coils......A,B,E primary/secondary which I dont understand because they are a solid unit.....replaced 5 of them...all i could get....and oem plugs. cleared codes....still have same problem and same codes....I have dealer manual and i am level 2 chrysler mechanic.....I no longer work for chrysler but know a lot about all vehicles...I cant check compression.....any other ideas..what about IAC solenoid ?...I am clueless...or should I find comp.tester....it acts like eng.timing is ruined but it seems like it isnt getting enough intake air.........please help.?

old fords have them and yours does to
mine not. ,not my JK Nor wk.

I have your real factory service manual here on screen 2.
yes, replacing the alternator with the battery connected does blow a fuse.
in 1 nano second fast. BOOM , let the smoke out. but saved by the link.
OKAY you were right the liberty has that link

you were right, it has links !



this is your actual car, wiring
i have it all there. FSM PDF real.

release the automatic tensioner. strip down and retention

You will need to consider whether it is the primary or secondary side of that coil that fails if possible. A primary side failure could be a failing engine control module causing excessive current to the coil causing it to burn out or internally short. If it is a secondary side failure, the issue is still high current, because the spark voltage is not delivered straight to the plug caused by leakage of the spark in the plug wire to ground, or plug gaps that are too close. Some coils are wired to fire two plugs simultaneous, one upon compression and one (probably) during exhaust in a series circuit, so check both gaps on that coil. And the other possibility is caused by not using resistance plug wires in favor of solid copper and non-resistive plugs as well, causing the secondary current to be very high.

I can't reason why any sensor would cause the coil failure. The basics for coil operation is a quick pulse of voltage to the primary causes a induction of voltage in the secondary when the voltage is removed from the primary. Usually the current in the primary is quite high to create the magnetic field for the secondary. It was the same for old point & condenser distributors as it is now for solid state controls. The problem now is that the solid state MOSFET's used in place of points can develop internal leakage or short altogether. This takes out the coil pack because of the ECM failure.

You are using Autolite plugs right? I find OEM plugs work best rather than trying things like Iridium or other performance options.

I forget which pack went out on my Freestar, but it was OEM coil pack, OEM plug sires & OEM plugs all the way!

Check Engine Light/Misfire Due to Intake Valve Locks ...

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Jeep Liberty Check Engine Light/Misfire Due to Intake Valve Locks/Valves. ...Misfire cyc 4 and random cyc misfires, changed coil packs and plugs... sounds as if rod ... Light came on again (misfire on cylinder 4) - switched coil from 4 to 2. Light ...

Jeep Liberty Questions - Cylinder Misfire code - CarGurus

www.cargurus.com > Questions > Jeep > Liberty

CarGurusMay 27, 2009 - #4 misfire new plugs and coil pack on #4 light came back on after 300 miles if ... How come it stopped misfiring for 2-3 months, and now is back? ... I have a 2005 Jeep Liberty 6 cylinder, engine light came on scaned the codes ...

Liberty Cylinder Misfire / Computer issue? - JeepForum.com

good luck

https://www.google.com/search?q=Horn+circuit+diagram+for+Jeep+Liberty+Sport+2002+Limited+Edition&rlz=1C1CHZL_enCA696CA696&espv=2&biw=1152&bih=547&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiz7dfx6cPNAhVD2IMKHax1CpQQsAQIGw

3.7 V6, mileage?

most likely the HV wires bad.

then bad coil pack.

did you check spark directly at the coil pack?

i use 2 known good HV wires to do that and 2 good test spark plugs.

both plugs grounded to engine (shell)

that is how you test any wasted spark coil pack. 3 coil pack.

if that fails the FSM shows, unplugging it and check the coil resistances. if wrong the pack is bad,

keep in mind the res. can read ok and coil be bad ,due to internal insulation break down (internal shorts)

if thats ok. the resistance , make sure the wires are not (primary)

to the coil (the low voltage connnector)

if that is ok, its mostly likely a bad coil, (pray not bad PCM)

if tool-less? start with cheap parts , work to expensive. (guessing)





now wasted spark 101.

if one line opens , both spark plugs die. no spark

the wasted spark is wired in SERIES. ( like Christmas lights)

the magic cuts cost of 6 coil\'s.

so if the HV wires are say, cheap , carbon wire and open

you lose, both spark plugs. use MAG wire and end this issues.

get some nice NGK mag wire or Bosch Mag wires.

you can see i hate carbon wire. for good causes.

(carbon string wire)

mag wires is real wire that is coil spun and is inductive. it

has the correct impedance but is not a resistor its and inductor.

and lasts the longest , and worth every penny.

Bad Plugs, Blocked Fuel Injectors, Bad Coil Pack

The rear wiper has its own pump motor. pull the hose from the wiper and have someone engage to see if there is a clog. do the same at the motor. if bo liquid comes out then its the pump. also check fluid level in reservoir as well as a possible secondary reservoir

THERE SHOULD BE ANOTHER CODE THAT IS LIKE THIS P0301 AND SO ON WITH THE LAST NUMBER BEING THE CYLINDER THAT IS MISFIRING, OTHERWISE YOU NEED TO ISOLATE THE CYLINDER THE HARD WAY, DISCONNECT THE COILS ONE AT A TIME.

should be a sticker with sized right inside the door jam or on door near latch.