1989 Jeep is pxxxin me off!!!!!!
11-02-2012, 06:30 AM
#31
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Join Date: Aug 2011
Location: Prescott, Az
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Hi guys,
Well my jeep is up and running again, after changing everything that needed to be changed we finally have a green light. The thing that seemed
to really work was the cleaning of all the ground connections and replacing the fuse.
Did have a problem with the clutch, really mussy, but fixed that problem
in a unique way. We had to bleed it like you do brakes, but I do not have a bleed screw on my clutch, so my friend had to pull off the clutch cylinder and physically push the rod. And it worked.
My suggestion to anyone experiencing problems with no spark to plugs, check your ground connections, make sure they are all clean and getting really good connection and then check all the fuses.
Good Luck
Well my jeep is up and running again, after changing everything that needed to be changed we finally have a green light. The thing that seemed
to really work was the cleaning of all the ground connections and replacing the fuse.
Did have a problem with the clutch, really mussy, but fixed that problem
in a unique way. We had to bleed it like you do brakes, but I do not have a bleed screw on my clutch, so my friend had to pull off the clutch cylinder and physically push the rod. And it worked.
My suggestion to anyone experiencing problems with no spark to plugs, check your ground connections, make sure they are all clean and getting really good connection and then check all the fuses.
Good Luck
Renix Ground Refreshing
The Renix era XJs and MJs were built with an under-engineered grounding system for the engine/transmission electronics. One problem in particular involves the multiple ground connection at the engine dipstick tube stud. A poor ground here can cause a multitude of driveabililty issues, wasted time, and wasted money replacing unnecessary components.
The components grounding at the dipstick tube stud are:
Distributor Sync Sensor, TCU main ground, TCU "Shift Point Logic", Ignition control Module, Injectors, ECU main ground which other engine sensors ground through, Oxygen sensor, Knock Sensor, Cruise Control, and Transmission Sync signal. All extremely important stuff.
The factory was aware of the issues with this ground point and addressed it by suggesting the following:
Remove the nut holding the wire terminals to the stud. Verify that the stud is indeed tightened securely into the block. Scrape any and all paint from the stud’s mounting surface where the wires will attach. Must be clean, shiny and free of any oil, grease, or paint.
Inspect the wire terminals. Check to see that none of the terminals are crimped over wire insulation instead of bare wire. Be sure the crimps are tight. It wouldn’t hurt to re-crimp them just as a matter of course. Sand and polish the wire terminals until clean and shiny on both sides. Reinstall all the wires to the stud and tighten the nut down securely.
While you’re in that general area, locate the battery negative cable which is fastened to the engine block just forward of the dipstick stud. Remove the bolt, scrape the block to bare metal, clean and polish the cable terminal, and reattach securely.
Another area where the grounding system on Renix era Jeeps was lacking is the engine to chassis ground. There is a braided cable from the back of the cylinder head that also attaches to the driver’s side of the firewall. This cable is undersized for it’s intended use and subject to corrosion and poor connections at each end.
First off, remove the cable end from the firewall using a 15mm wrench or socket. Scrape the paint off down to bare metal and clean the wire terminal. Reattach securely.
Remove the other end of the cable from the rear of the head using a 3’4" socket. Clean all the oil, paint and crud from the stud. Clean the wire terminal of the cable and reattach securely.
A suggestion regarding the braided cable:
I prefer to add a #4 Gauge cable from the firewall to a bolt on the rear of the intake manifold, either to a heat shield bolt or fuel rail bolt. A cable about 18" long with a 3/8" lug on each end works great and you can get one at any parts store already made up. Napa has them as part number 781116.
A further improvement to the grounding system can be made using a #4 cable, about 10" long with 3/8" terminals at each end. Attach one end of this cable to the negative battery bolt and the other end under the closest 10mm headed bolt on the radiator support just forward of the battery. Napa part number 781115.
If you want to upgrade your grounds and battery cables in general, contact Jon at www.kelleyswip.com. He makes an incredible cable upgrade for a very reasonable price.
Revised 11-28-2011
11-02-2012, 06:32 AM
#32
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Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,971
Received 1,559 Likes
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1,263 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Have you pulled the dizzy cap? The only thing you have not looked at seems to be the cam position sensor inside the distributor. Hot wire the coil to be certain it is maintaining voltage to the coil. If it still has no spark you have to check the cam position sensor inside the distributor.
CAMshaft Position Sensor / Sync Pulse (Stator) Test
This article is intended to help you diagnose intermittant ignition problems that cannot be attributed to other sensors or the more failure prone Crankshaft Position Sensor. The CAM-shaft position sensor (aka 'stator' or sync pulse generator) lets the ECU know when to pulse the fuel injectors and co-ordinates with the Crankshaft Position Sensor for engine timing.
WARNING!: The term CPS is most often used to describe the CRANKshaft position sensor! Be SURE to get the correct sensor! Both the crank and cam position sensors work together feeding the ECU (computer) information on the engine timing to fire the injectors and maintain engine timing. In the case of the Jeep 4.0L engine: the CAMshaft position sensor is also called the 'sync pulse generator' (or stator) and can be found in the "distributor" while the CRANKshaft position sensor is located on the transmission bellhousing.
Don't be surprised if your counter drone tries to hand you the wrong part as there are several common names in use for the Camshaft Position Sensor:
camshaft position sensor
stator
sync-pulse generator
"...Auto Zone had the (sync signal generator) but they call it a pick-up coil...
Stator Test Procedure
Sync Pulse (Stator) Test: Do NOT disconnect your "distributor" to do this test! Backprobe the connectors by inserting the voltmeter's probes into the connector where the wires enter the connector from the distributor or harness! You'll have to make sure that you have good contact but it's not hard to do... the connector MUST remain connected to do these tests!
While you can check the voltages and continuity with a digital volt meter... you will also need an ANALOG volt meter (with a needle... not digital readout) to check the stator's function.
RENIX TEST PROCEDURE
1)Insert + voltmeter lead into BLUE wire at distributor connector.
2)Insert negative - lead into Gray W/trace wire at dist connector.
3)Set voltmeter to 15vac, turn key on & should show approximately 5.0volts.
4)If there is no voltage present - double check the backprobed leads to ensure good contact.
5)If there is STILL no voltage present; the Factory Service Manual says you need to "Perform vehicle test using DRB II tester. I don't have one. You don't either.
6)At this point, If you DO have voltage then remove / disconnect the ECU (computer).
7)Check continuity between the Blue wire and C-16 at the ECU. - If no continuity: repair harness wire.
8)Check continuity between Gray W/trace and pin C-5 at the ECU. - If no continuity: repair harness wire.
9)Check continuity between Black wire and "ground". - If no continuity: repair harness wire.
While observing analog voltmeter (That's one with a needle, folks! Your average digital meter won't show this...) crank engine & voltmeter needle should fluctuate back & forth while engine is cranking over. This confirms stator in distributor is 'pulsing' correctly and sending signal out for ECU.
10)If there is no sync pulse you will have to replace the stator by removing and dissassembling the "distributor" following the service manual procedure. * - Helpful Hint: Before pulling your distributor... "bump" the engine until the rotor is pointing straight forward and aligned with the side of the engine. That way you'll know where the rotor needs to end up pointing after reassembly.
CAMshaft Position Sensor / Sync Pulse (Stator) Test
This article is intended to help you diagnose intermittant ignition problems that cannot be attributed to other sensors or the more failure prone Crankshaft Position Sensor. The CAM-shaft position sensor (aka 'stator' or sync pulse generator) lets the ECU know when to pulse the fuel injectors and co-ordinates with the Crankshaft Position Sensor for engine timing.
WARNING!: The term CPS is most often used to describe the CRANKshaft position sensor! Be SURE to get the correct sensor! Both the crank and cam position sensors work together feeding the ECU (computer) information on the engine timing to fire the injectors and maintain engine timing. In the case of the Jeep 4.0L engine: the CAMshaft position sensor is also called the 'sync pulse generator' (or stator) and can be found in the "distributor" while the CRANKshaft position sensor is located on the transmission bellhousing.
Don't be surprised if your counter drone tries to hand you the wrong part as there are several common names in use for the Camshaft Position Sensor:
camshaft position sensor
stator
sync-pulse generator
"...Auto Zone had the (sync signal generator) but they call it a pick-up coil...
Stator Test Procedure
Sync Pulse (Stator) Test: Do NOT disconnect your "distributor" to do this test! Backprobe the connectors by inserting the voltmeter's probes into the connector where the wires enter the connector from the distributor or harness! You'll have to make sure that you have good contact but it's not hard to do... the connector MUST remain connected to do these tests!
While you can check the voltages and continuity with a digital volt meter... you will also need an ANALOG volt meter (with a needle... not digital readout) to check the stator's function.
RENIX TEST PROCEDURE
1)Insert + voltmeter lead into BLUE wire at distributor connector.
2)Insert negative - lead into Gray W/trace wire at dist connector.
3)Set voltmeter to 15vac, turn key on & should show approximately 5.0volts.
4)If there is no voltage present - double check the backprobed leads to ensure good contact.
5)If there is STILL no voltage present; the Factory Service Manual says you need to "Perform vehicle test using DRB II tester. I don't have one. You don't either.
6)At this point, If you DO have voltage then remove / disconnect the ECU (computer).
7)Check continuity between the Blue wire and C-16 at the ECU. - If no continuity: repair harness wire.
8)Check continuity between Gray W/trace and pin C-5 at the ECU. - If no continuity: repair harness wire.
9)Check continuity between Black wire and "ground". - If no continuity: repair harness wire.
While observing analog voltmeter (That's one with a needle, folks! Your average digital meter won't show this...) crank engine & voltmeter needle should fluctuate back & forth while engine is cranking over. This confirms stator in distributor is 'pulsing' correctly and sending signal out for ECU.
10)If there is no sync pulse you will have to replace the stator by removing and dissassembling the "distributor" following the service manual procedure. * - Helpful Hint: Before pulling your distributor... "bump" the engine until the rotor is pointing straight forward and aligned with the side of the engine. That way you'll know where the rotor needs to end up pointing after reassembly.
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