duckyge

I have a 02 jeep grand cherokee laredo 4.0 In line 6 and i changed the camshaft sensor and crank shaft sensor but it still wont start and its back firing through throttle body i think its timeing but idk how to set it right please help im in desperate need!

highspeed

Are you getting fuel?

Are you getting Spark?

Backfiring sounds like a possible timing issue, but it could be a few things.

Start systematically with Spark, Fuel, and Air and expand from there. Any CELs?

duckyge

im getting spark fuel and air and idk what the other thing is

dave1123

CEL; check engine light. Actually, trouble codes. Was it backfiring before you changed the sensors or was that the result? It gets expensive just throwing parts at the problem without diagnosing the problem beforehand.

duckyge

All it did was turn over before the sensors due to no spark after i changed the cks it got fire and started back firing the engine light blinked 10 or 11timesi think the timing is off 180°

dave1123

That is very possible! Also easy to fix. Bring the engine to TDC, pull the cam sensor out, turn the shaft 1/2 turn, and put it back in. I can't tell you how many times I've seen this problem in my life. Many people don't realize an engine comes to TDC TWICE in each ignition cycle. Once for exhaust and once for ignition. When I was very young, we had an old Plymouth straight 6 that wouldn't start after a point change. We towed it and when we popped the clutch, a steady flame came out of the carberauter! After recovering from laughter, we realized we had we had done!

Looks to me like you solved your own problem, just didn't process the information.

Welcome to CF! Have a safe and sane holiday season.

duckyge

Ok im gonna distribute it with an hei distributor is there a place i need to run a vacume advance to?

ol"blue

Welcome to CF. Don't try to use an older style distributor, that will only cause more problems than you're trying to cure. Stick with the factory equipment, just install the replacement parts correctly.
It sounds like you need to reestablish Cam Sensor relationship*. The following comes from the WJ Factory Service Manual.

REMOVAL
OIL PUMP DRIVE AND SENSOR - 4.0L
If the CMP and oil pump drive are to be
removed and installed, do not allow engine
crankshaft or camshaft to rotate. CMP sensor
relationship will be lost.
(1) Disconnect electrical connector at CMP sensor
(Fig. 7).
(2) Remove 2 sensor mounting bolts (Fig. 6) or
(Fig. 7).
(3) Remove sensor from oil pump drive.
(4) Before proceeding to next step, mark and note
rotational position of oil pump drive in relationship
to engine block. After installation, the CMP sensor
should face rear of engine 0°.
(5) Remove hold-down bolt and clamp (Fig. 7).
(6) While pulling assembly from engine, note direction
and position of pulse ring (Fig. 6). After removal,
look down into top of oil pump and note direction and
position of slot at top of oil pump gear.
(7) Remove and discard old oil pump drive-to-engine
block gasket.

INSTALLATION - 4.0L
OIL PUMP DRIVE AND SENSOR - 4.0L
(1) Clean oil pump drive mounting hole area of
engine block.
(2) Install new oil pump drive-to-engine block gasket.
(3) Temporarily install a toothpick or similar tool
through access hole at side of oil pump drive housing.
Align toothpick into mating hole on pulse ring (Fig.
8).
(4) Install oil pump drive into engine while aligning
into slot on oil pump. Rotate oil pump drive back
to its original position and install hold-down clamp
and bolt. Finger tighten bolt. Do not do a final tightening
of bolt at this time.
(5) If engine crankshaft or camshaft has been
rotated, such as during engine tear-down, CMP sensor
relationship must be reestablished.*
*(a) Remove ignition coil rail assembly. Refer to
Ignition Coil Removal/Installation.
(b) Remove cylinder number 1 spark plug.
(c) Hold a finger over the open spark plug hole.
Rotate engine at vibration dampener bolt until
compression (pressure) is felt.
(d) Slowly continue to rotate engine. Do this
until timing index mark on vibration damper pulley
aligns with top dead center (TDC) mark (0
degree) on timing degree scale (Fig. 9). Always
rotate engine in direction of normal rotation. Do
not rotate engine backward to align timing marks.
(e) Install oil pump drive into engine while
aligning into slot on oil pump. If pump drive will
not drop down flush to engine block, the oil pump
slot is not aligned. Remove oil pump drive and
align slot in oil pump to shaft at bottom of drive.
Install into engine. Rotate oil pump drive back to
its original position and install hold-down clamp
and bolt. Finger tighten bolt. Do not do a final
tightening of bolt at this time.
(f) Remove toothpick from housing.
(6) Install sensor to oil pump drive. After installation,
the CMP sensor should face rear of engine 0°.
(7) Install 2 sensor mounting bolts and tighten to
2 N·m (15 in. lbs.) torque.
(8) Connect electrical connector to CMP sensor.
(9) If removed, install spark plug and ignition coil
rail.
To verify correct rotational position of oil pump
drive, the DRB scan tool must be used.

WARNING: WHEN PERFORMING THE FOLLOWING
TEST, THE ENGINE WILL BE RUNNING. BE CAREFUL
NOT TO STAND IN LINE WITH THE FAN
BLADES OR FAN BELT. DO NOT WEAR LOOSE
CLOTHING.

(10) Connect DRB scan tool to data link connector.
The data link connector is located in passenger compartment,
below and to left of steering column.
(11) Gain access to SET SYNC screen on DRB.
(12) Follow directions on DRB screen and start
engine. Bring to operating temperature (engine must
be in “closed loop” mode).
(13) With engine running at idle speed, the words
IN RANGE should appear on screen along with 0°.
This indicates correct position of oil pump drive.
(14) If a plus (+) or a minus (-) is displayed next to
degree number, and/or the degree displayed is not
zero, loosen but do not remove hold-down clamp bolt.
Rotate oil pump drive until IN RANGE appears on
screen. Continue to rotate oil pump drive until
achieving as close to 0° as possible.
The degree scale on SET SYNC screen of DRB is
referring to fuel synchronization only. It is not
referring to ignition timing. Because of this, do
not attempt to adjust ignition timing using this
method. Rotating oil pump drive will have no effect
on ignition timing. All ignition timing values are controlled
by powertrain control module (PCM).
(15) Tighten hold-down clamp bolt to 23 N·m (17
ft. lbs.) torque