Changed relays, but no help.
No spark to all 6 cylinders, or just 2 ????????????????????????
did you check all fuses first??????????
did you check that the CEL lamp glows, key on? MIL lamp?
if not? the main is dead, or fuse dead.(blown)
ok this is the very very old and obscure Jeep Bendix/Renix system.
the hard part is , it is NOT OBD1 engine yet, making diagnosis very hard. and no distributor. (new for MPI)
is yours the 4.0 I-6
and is it the 1 year, MPI engine? WITH MAF SENSOR!!
this is and AIR DENSITY SYSTEM unlike most other jeeps.
1989 - Changed to Renix MPFI. (read 4 injectors now>....)
i owned a 88 Comanche, love it. 200,k miles i drove from 0
other that ISC motor, zero issues. mine was TBI , no MAF.
NO spark.,?
this MPI has a coil pack with 3 coils in side, and uses the famous.
wasted spark design, even my new jeep v6 has this.
the coil is driven by a separate ICM , ignition control module.
The ICM, iis driven by the PCM(ECU)
your car has a CKP sensor (crank) fitted to the BELL
for the 3 marks, on the flywheel
quote FSM.
The Crankshaft Position Sensor (CKP) is secured by special shouldered bolts to the flywheel/drive plate housing. It is preset in its mounting at the factory and is non-adjustable in the field.
uq:
this means it tunes like a marconi radio, its not a hall sensor...!!!
its just a coil with weak outputs.
is it loose?
id do not know where the CAm CMP sensor is.
the online books mix 5 systems bad, this engine was EFI was
a one year only system. (French)
My wild guess is the CMP is this funny device, on the right
side of engine, where the DIZZY USED to be. called the cam sensor.
that too, must work and i think its a hall sensor and is very easy to test.
sadly no OBD1 and no CEL: flash codes.
to blink out, CMP/CKP dead. cranking
just very old factory scan tool works
again, all spark dead or only 2?
SOURCE: finding the relay for electric fan on '89 jeep cherokee laredo 4.0
It is on the driver fender near air filter housing. Also next to the fuel pump ballast resistor. It is the white 3 inch long piece of ceramic on the fender with eletricial connectors on each end.
SOURCE: 2002 Jeep Grand Cherokee Lardo misfiring
You say you changed the cam sensor. A1391 code is a crank sensor on the top of the trans. bell housing.
SOURCE: 89 Jeep Comanche Fuel Pump. Won't start after running great.
Replace the crankshaft position sensor
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