I have a 2001 Jeep Grand Cherokee 2WD with a 4.0 engine and auto transmission, I am getting code P1391. I have replaced: camshaft position sensor, crankshaft position sensor, spark plugs, gas cap, and ECM (computer). But I still ge code P1391, when driving down the road the engine starts sputtering, pulled over, rev engine as long as high RPM sounds fine, let off gas at 1500 RPM started trying to quit, drove it to have codes checked and cleared, restarted and drove home did code check again showed code P1391, what do I need to do now
I would check to be sure that the timing chain hasn't jumped at all ..
Why would you rate this as Inappropriate? Did you check your timing?
My suggestion is you rotate your distributor ans see if you can make the engine run smoother .. if so .. you have a timing problem.
Have you checked the timing/timing chain yet?
WJ jeep 4L inline 6
OMG, its a 2001 not 93-98 !!!! sorry. fella.
i guess you've never seen a 4L engine>.
do not mess with the distributor. 1993-1998
but in 1999 that ended, same HERE.
and has a 3 coil coil rail pack
Sorry no Distrib now.
and these engines do not drop chains.
like some chezzy rice burner.
1391 is cmp/ckp failure. try to focus on that.?
think this chain fails, not often.
but miles on engine would help and not stated. this is 4L robust short chain.
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To other posters, omg, its not a wranger, nor is it a 1993 to 1998 grand Cherokee, its a 2001, read the post again,,
WITH D.I.S SPARK NOW.
the 4.7L is overhead cam, the 4.0L IS NOT. so has no head cam or head chain, that like to fail...
stop guessing please.
P1391
that is a factory DTC code P1. is that. (means dont read GM codes for that, only jeep , only 4L)
even the engine stated, like first time here ever, it seems.?
4L (1 of 5 million made)
so how to work sensor errors,
sure a loose cam drive can cause the cam sensor to go nuts.
but not common on 4L.
so can , wires to the sensor bad, (look yet) and a dirty (metal mud) contaminated sensor ( clean it? )
the real problem is our scan tools can not see the deeper codes
for is it the CMP or CKP failing SEE????????
it just says both.
many here hate books (sad to watch) but is covered in the freakn book. in depth....
the 2001 CMP is where the old distributor WAS.
see that on center of left side of block
and it can fail. sure.
it is gear driven just like the distrib. was before 1999.
first a warning in the (factory book)
On the 4.0L 6-cylinder engine, do not attempt to
rotate the oil pump drive to adjust timing. This
adjustment is used for fuel synchronization after
camshaft position sensor replacement.
got that? so if replacing THAT, it needs to be timed, for fuel injection POINT. (the method takes a toothpick, ask)
now the CKP (no factory scan tool, so DIY folks must guess)
the CKP must not be just fiddle with or swapped
the method if adjusting it and the spacer.
both sensors are HALL sensors.
on the old engines the CKP was very fussy 2 wire coil sensor
tuned like a radio . and very weak signals! not now ,.
now the rules for messing the CKP, 4.0L ONLY !
The sensor is adjustable
and is attached with one bolt. A wire shield/
router is attached to the sensor (Fig. 21).
(1) Disconnect sensor pigtail harness (3-way connector)
from main engine wiring harness.
(2) Remove sensor mounting bolt.
(3) Remove wire shield and sensor.
INSTALL TIME:
The Crankshaft Position (CKP) sensor is mounted
to the transmission bellhousing at the left/rear side
of the engine block (Fig. 21). The sensor is adjustable
and is attached with one bolt. A wire shield/
router is attached to the sensor (Fig. 21).
New replacement sensors will be equipped with a
paper spacer glued to bottom of sensor. If installing
(returning) a used sensor to vehicle, a new paper
spacer must be installed to bottom of sensor. This
spacer will be ground off the first time engine is
started.
WARNING !!!
If spacer is not used, sensor will be broken
the first time engine is started.
(1) New Sensors: Be sure paper spacer is installed
to bottom of sensor. If not, obtain spacer
PN05252229.
(2) Used Sensors: Clean bottom of sensor and
install spacer PN05252229.
(3) Install sensor into transmission bellhousing
hole.
(4) Position sensor wire shield to sensor (Fig. 21).
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i post all this for 1 reason
if you mess with both sensors and dont know how to adjust them
you just made it worse.! sorry but that is a fact.
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RECAP
the cam is loose. (not very likely on any 4.0L
the cmp is misfiring
the CKP is misfiring.
that be it.
if for sure not other codes,,,, this poster shows ONLY one DTC code, so we must believe that.
I drive and log codes.
while it misfires. and win. and see all codes.
some clear fast. (a secret about spark codes many dont know)
one needs to look for ALL P03xx codes. running !!!
i have more, lots more, if you had gone to the dealer , he can scan it (if failing now)
and see which sensor is failing. sure can.
I'm not a proponent of any stealership EVA!
but if you buy your own scanner and drive while engine is running and misfiring!
you will see P0320 or P0340!!!, with 1391's
LIVE FAILING and 320/340 correcting in SECONDS. (that is its way, logic....)
this is how can PCM's work, (i repair PCM's+)
320 is crank
340 is cam,
now you have 1/2 the work, to find cause.
think of 1391 as and echo of the past.
and the other two, LIVE FAIL NOW.
here are some other facts.
you failed to look at the FREEZE FRAME
it will (may) show which sensor failed, at 1391. LOOK and WIN?
or PENDINGS. this shows marginal failures.
if say you say P320s, pending
well, you know the crank sensor is failing.
the key to finding bad things here.
is to SCAN AND DRIVE.
or spend eternity gue$$ing.
so trips to the zone and simple scans don;t work, what is new there?
find a REAL ASE shop and get them to scan it failing LIVE.
PS> try not to make it worse.
it easy , with both CMP and CKP.
timing and the tricky gaps.
The best comments I've ever read in any form!!! All Aug 23, 2015 comments. Also, thank you!! Helped me problem solved
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I have this problem haven't changed the sensors yet I have error codes p0340 p0320 p1391 what should I do??????
please dont piggyback. start fresh post.
fixing 2 engines same time 1 thread, is crazy.?
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You may have a bad coil pack , that's what fixed mine.
My Wrangler did the same thing. Turned out a battery problem from yrs ago (leaked onto the harness) had eatten into the harness and was shorting out. In fact, several wires were shorting.
BTW, you can not time these motors. In my 40 yrs of building Hot Rods and Rock Crawlers, I've NEVER seen a rig "jump time" and not require MAJOR valve/piston/EVERYTHING work.
I;m sure your efforts are appreciated but they are not helpful or needed.
DID YOU FORGET TO PUSH DTC RESET ON THE SCAN TOOL
AT EACH REPLACED PART??
THEN DRIVE FOR 2 DAYS SEE IF IT COMES BACK?
2 DRIVING CYCLES FOR SOME DTC TO TRIP
PUSH TOOLS PENDING DTC BUTTON? YET?
NO MILES TOLD IN THIS ENGINE,
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Maybe the ECM needs a reset?
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Usually answered in minutes!
The timing has been checked, it is fine.
I guess I felled to mention that the timing had been checked and it is fine
having the same problems
1998 jeep cherokee runs great check engine code is p1391
ran fine quit wont start getting gas and spark 4.7 motor
codes: p1391, p0300, p0303, p0304,p0306
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