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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 ...
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 ...
Cold starting misfires can often be caused by either tired high tension spark plug leads or ignition coil packs. If replacing leads, then replace with a full, new set. Coils can be changed individually, but it is often the case that if one has failed, then the others aren't far behind. Some cars have individual coil packs on each spark plug. Some cars have a single pack for all plugs and some have coil packs which may control two or more plugs.
To check for a misfire (ignition failure) follow these steps:
(Cold start) (Use a pair of insulated pliers)
1) Start the vehicle
2) When the vehicle starts misfiring, disconnect plug leads or coil pack connections one at a time. If the vehicle idles even more roughly, then that plug or pack should be considered fine.
Replug each connection before disconnecting the next one. Once you disconnect a plug lead or coil pack connection and find no difference in poor engine running, then you have likely found the offending cylinder. Check the spark plug condition, lead and/or coil condition and connections on that cylinder.
Try swapping the coil packs around - like swap #1 with #2, and swap #6 with #5, see if the misfires MOVE with the coil packs swapped to the new cylinders or if they stay with the cylinders. If they move with the coil packs, the new coil packs are bad. If they stay with the cylinders, there's a problem with those cylinders. You DID replace that camshaft sensor, right?
the coil. ? older post.
the PCM reports even one drop out of 10 , on the CKP or CMP sensors. 99.9% of these changed are good.
why not tell me what you have,? full symptoms and evidence.
got P030x misfiring? are you even using a scan tool,? or working blind.
may be its the coil.?
can can you feel the misfiring.c
can you see the engine shake? all of this is evidence.
do not miss out on that.
does the scan too shop pending misfire codes?
stored codes, or codes while driving, learn to use the scan tool.
do a 60k mile tune up yet?
your engine is not COP coils like the V8
its COIL rail that is a COIL pack with 3 coils inside
that runs 2 sparks each called WASTED park.
so did you try new sparkplugs(dah)first then new coil pack wires HV
next , then a new coil pack last.
start with the cheap spark plug and wires, (called a tuneup)
then pop for coil pack./
misfire can be clogged or leaking injectors too, and that ill skip
with out you using the scan tool fully.
Sounds like it's either a coil pack or an injector to me, try switching the number four coil pack with any of the other coil packs if the miss follows the coil pack you need to replace that coil pack. if not it's either a fuel injector or a mechanical problem inside the motor, I would rent noid lights from a local auto parts store and look for injector pulse in the cylinder with a misfire, if the noid light is flashing it may be better to leave it to a professional as it is likely internal engine damage. hope that helps. chris
P0306 is cylinder 6 misfire..P0316 is misfire in the first 1000 revolutions. A proper tune up will probably take care of the code. This includes spark plugs. I have the Mercury Mariner equivelent engine and you will need to remove the upper intake plenum to replace the plugs. It is plastic so take extra care when removing and re installing. I did not have to use new gaskets. There is a "coil pack" on each spark plug so no wires to change. I would change the air and fuel filter also.
Here is a diagram of the firing order for you 3800 engine. Cylinders 1 and 4 are misfiring because the operate under the same "Coil Pack" and the coil pack has unfortunately gone bad. O'Reilly sells them for between $30-50 depending on the amount of warranty coverage you want. To replace, simply unscrew the screws that hold the coil pack in place. WAIT before unplugging the plug wires. Place the old coil pack and new coil pack next to each other, unplug one plug wire, then plug it to that same port on the new coil pack. then do the same for the other plug wire. Then screw your new coil pack in place, and start you car. should run fine!
The problem is the ignition control module such is under the coil packs. It seems to be an internal problem in the design. I have seen it many times and if you don't belive as many will not. So disconnect the modules electrical connector and just let it sit for two to three days. After that clean ir replace your sparkplugs, they will be fails up dew to it running lean and rich. Plug it in. Plug it in and wala its fixed $ but only for a week or two then back to the same thing so in short change the ignition module and save time and money, and don't forget to thank your friendly neighbor hood mexican mechanic.
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