No spark issue plz help - JeepForum.com
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post #1 of 19 Old 03-03-2020, 12:59 PM Thread Starter
jerseyjeeper09
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No spark issue plz help

So after engine swap (98 Wrangler 4.0L ), I got it running and proceeded with break in instructions per the engine builder. It ran fine for about 15 minutes then backfired and died. Now it won’t start and I have no spark. I tested the two wires going into the coil, there is power to the white one while cranking, nothing to the green wire. I read somewhere that the green should have constant voltage, not sure if this is correct Also, my multi meter took a dive so at the moment I only have a test light. Anyone have any ideas? I’ve read the CPS can cause problems...Also, I replaced the coil when I did the motor swap because my old one was cracked all over. Like I said it started up and ran great for about 15 minutes then just died.
Thanks for any help...

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post #2 of 19 Old 03-03-2020, 01:17 PM
Jerry Bransford
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Check your crankshaft position sensor. ESPECIALLY if you installed a store brand CPS.

When you have a choice, buy American made.
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post #3 of 19 Old 03-03-2020, 01:17 PM
jtec
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ok test light only. Lets try 1.2 3.
I am guessing you do not have a scanner?

1) Unplug connector at coil - there should be 12v on the OR/DG (oragne wire). yes or no?
>>>No power check fuse #21 PDC.

2) you said there is 12v on GR (gray) wire. yes or no?
>>> should be NO power so DBL check. post answer

3) Is the CEL on and does itcome on @2seconds every time you start? yes or no

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #4 of 19 Old 03-03-2020, 01:49 PM Thread Starter
jerseyjeeper09
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Quote:
Originally Posted by Jerry Bransford View Post
Check your crankshaft position sensor. ESPECIALLY if you installed a store brand CPS.
I did not replace it the motor had one installed already. How do I check it
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post #5 of 19 Old 03-03-2020, 01:51 PM Thread Starter
jerseyjeeper09
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Quote:
Originally Posted by jerseyjeeper09 View Post
Quote:
Originally Posted by Jerry Bransford View Post
Check your crankshaft position sensor. ESPECIALLY if you installed a store brand CPS.
I did not replace it the motor had one installed already. How do I check it
I mean it’s the original cps from my motor
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post #6 of 19 Old 03-03-2020, 01:57 PM Thread Starter
jerseyjeeper09
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Quote:
Originally Posted by jtec View Post
ok test light only. Lets try 1.2 3.
I am guessing you do not have a scanner?

1) Unplug connector at coil - there should be 12v on the OR/DG (oragne wire). yes or no?
>>>No power check fuse #21 PDC.

2) you said there is 12v on GR (gray)
wire. yes or no?
>>> should be NO power so DBL check. post answer

3) Is the CEL on and does itcome on @2seconds every time you start? yes or no
Ok after looking closer the wire is orange. It has power only while cranking the engine. The other wire (grey) has no power at all
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post #7 of 19 Old 03-03-2020, 01:59 PM Thread Starter
jerseyjeeper09
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The cel comes on And stays on the entire time I’m cranking the motor
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post #8 of 19 Old 03-03-2020, 02:25 PM
Jerry Bransford
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Have you used a code reader to see if there are any codes present? A bad CPS would cause a no spark condition and it's vulnerable to damage while doing the kind of work you did when replacing the engine.

When you have a choice, buy American made.
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post #9 of 19 Old 03-03-2020, 02:25 PM
jtec
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the orange wire should have 12v key on engine off KOEO - without cranking is there 12v on this wire?

there should be NO v on gray wire with connector unplugged.

With KOEO does the CEL stay on after 2seconds?


connector unplugged one end of test light in each cavity of coil wire connector.
When cranking the engine the test light should flash - yes no?

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #10 of 19 Old 03-03-2020, 02:41 PM Thread Starter
jerseyjeeper09
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Quote:
Originally Posted by jtec View Post
the orange wire should have 12v key on engine off KOEO - without cranking is there 12v on this wire?

there should be NO v on gray wire with connector unplugged.

With KOEO does the CEL stay on after 2seconds?



connector unplugged one end of test light in each cavity of coil wire connector.
When cranking the engine the test light should flash - yes no?
I had someone sitting inside the Jeep helping so I can be more specific. Key on, orange wire has power for about two seconds, then turns off. When cranking the engine, it does the same thing, two seconds then off, even while cranking. It does not flash. The gray wire does not ever get energized. The CEL comes on as soon as the key is turned on, and never goes back off. It did not come on while it was running earlier
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post #11 of 19 Old 03-03-2020, 02:47 PM Thread Starter
jerseyjeeper09
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Quote:
Originally Posted by Jerry Bransford View Post
Have you used a code reader to see if there are any codes present? A bad CPS would cause a no spark condition and it's vulnerable to damage while doing the kind of work you did when replacing the engine.
I did not get a chance to have it read, it ran for about 15 minutes on initial start-up, but I didn’t actually drive it anywhere, and then it died. I believe I’m just going to go buy a cps and give it a try
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post #12 of 19 Old 03-03-2020, 03:25 PM
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I think jerrry was on this fast - no flashing so CKP sounds like the issue, ALSO can you check the system for codes?

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #13 of 19 Old 03-03-2020, 03:55 PM Thread Starter
jerseyjeeper09
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Alright rented a scanner and bought a crank. pos sensor. The scanner is telling me it’s the camshaft position sensor tho, code P0340
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post #14 of 19 Old 03-03-2020, 03:59 PM Thread Starter
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Is there any way to check these with a meter
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post #15 of 19 Old 03-03-2020, 04:12 PM
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This is what the FSM has on the testing of the CMP semsor.



CAMSHAFT POSITION SENSOR



The camshaft position sensor is located in the distributor on all engines.
To perform a complete test of this sensor and its circuitry, refer to the appropriate Powertrain Diagnostics Procedures service manual. To test the sensor only, refer to the following:



For this test, an analog (non-digital) voltmeter is needed. Do not remove the distributor connector from the distributor. Using small paper clips, insert them into the backside of the distributor wire harness connector to make contact with the terminals. Be sure that the connector is not damaged when inserting the paper clips. Attach voltmeter leads to these paper clips.



(1) Connect the positive (+) voltmeter lead into the sensor output wire. This is at done the distributor wire harness connector.
(2) Connect the negative (-) voltmeter lead into the ground wire.
(3) Set the voltmeter to the 15 Volt DC scale.
(4) Remove distributor cap from distributor (two screws). Rotate (crank) the engine until the distributor rotor is approximately in the 11 o’clock position. The movable pulse ring should now be within the sensor pickup.
(5) Turn ignition key to ON position. Voltmeter should read approximately 5.0 volts.
(6) If voltage is not present, check the voltmeter leads for a good connection.
(7) If voltage is still not present, check for voltage at the supply wire.
(8) If 5 volts is not present at supply wire, check for voltage at PCM 32-way connector (cavity A-17). Leave the PCM connector connected for
this test.
(9) If voltage is still not present, perform vehicle test using the DRB scan tool.
(10) If voltage is present at cavity A-17, but not at the supply wire:
(a) Check continuity between the supply wire. This is checked between the distributor connector and cavity A-17 at the PCM. If continuity is not present, repair the harness as necessary.
(b) Check for continuity between the camshaft position sensor output wire and cavity A-18 at the PCM. If continuity is not present, repair the harness as necessary.
(c) Check for continuity between the ground circuit wire at the distributor connector and ground. If continuity is not present, repair the harness as necessary.
(11) While observing the voltmeter, crank the engine with ignition switch. The voltmeter needle should fluctuate between 0 and 5 volts while the engine is cranking. This verifies that the camshaft position sensor in the distributor is operating properly and a sync pulse signal is being generated. If sync pulse signal is not present, replacement of the camshaft position sensor is necessary
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