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Old 12-02-2012, 03:05 PM   #1
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no spark, no ideas left

So basically the background of what happened:
I threw a rod through my oil pan but pretty much dumped my whole third cylinder into the oil pan. So I just counted that engine as a loss, which was a 1998 2.5L engine. I decided to just throw a used 1997 2.5L that was certified good that i found online and had it shipped to me already (I know how many people strongly advise to just do bigger swap, but I am going do one when I get the money) So i have already put the new engine in and can not get a spark with anything that I try we can however get it to crank, just not turn over.

Here's what we've done so far:
-Checked for voltage at the cam position sensor: we got 5V in all the plugs? seems weird that they were all constant even with the jeep just on, not even cranking. We even rotated the engine to try to get the sensor out of the pick up, but it still reads the same. The sensor came off of my old Jeep which was working when it threw the rod, so I assume it is still good?
-We have done continuity checks throughout everything, so no wires were severed and they all match up to the diagram for the connectors going into the pcm.
-I went ahead and replaced the crank position sensor. I looked online and saw that it should show infinite resistance between terminals b and c, but both the old one and new one showed some resistance, not much, but some?
-We swapped the ASD relay with the horn relay and it checked out fine

I am popping some codes: P0123, P0118, P0113, P0463, and P1492. I searched for all of these and I know P0118 is the only one I found that could cause a no spark condition and thats the engine coolant temperature sensor circuit high or something.

I was wondering if the ECM/PCM would work from my 1998 with the new 1997 engine?
Any advice would be helpful. I am a big do it yourself guy, but I am ready to take it to a mechanic!

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Old 12-02-2012, 05:17 PM   #2
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All those codes are for high voltage to various sensors. Even though there are no codes for the cam & crank sensors they are connected to this same 5v circuit. The 5v & these sensors return to the C2 (middle) connector on the PCM & are all spliced (connected) together. Check that connector especially the orange (5v) wire & the brown/yellow (return) wire. They are in positions 17 & 4. Also make sure the MAP & TPS are properly connected.

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Old 12-02-2012, 06:42 PM   #3
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I just went through this with my 98 4.0 but I think it should apply here as well:

Cam and Crank sensors - leave the connector plugged in and Back probe the connector with the ignition in the "run" position" you should have 5V to one of the wires constant, the next wire should have 5V then 0V as you manually rotate the engine and the last one is a ground (applies to both).

Using a spark tester or a screw driver, disconnect one of the plug wires and ground it... If you get a good spark then you need to start looking elsewhere (fuel and / or compression)

If no spark then unplug the coil wire at the cap and ground it like above... If you get a good spark then you need to start looking elsewhere (fuel and / or compression)

If you do not get a spark then unplug the distributor and check for 12V while the engine is cranking over.

if you are getting 12V into the coil and nothing out then it sounds like the coil may be bad...

Good luck
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Old 12-02-2012, 07:29 PM   #4
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did ya swap all the sensors including the dist pick up, I believe some from 97-98 were different, I found this out when I put a 94 motor in my 98
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Old 12-02-2012, 10:17 PM   #5
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well i am definitely not getting 12v even up to the coil. what and where are the MAP and TPS?
and yes, i swapped everything i can think of over: whole distributor assembly that goes into the cam, the coil, throttle body assembly.
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Old 12-03-2012, 12:45 AM   #6
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Read up on the ignition & fuel system in the FSM here. TPS & MAP are explained in the fuel section.

If the distributor is even 1 tooth off it won't start so check that as well (instructions on that in the FSM). That fixed a no start, no spark for this guy.

Fresh out of ideas. 2.5l 1999 tj not starting

See online read only FSMs here:
Jeep Knowledge Base
You may have to go to the bottom of the page & pick Jeep Resources & online manuals if it directs you to home page rather than the knowledge base.
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Old 12-03-2012, 11:37 AM   #7
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I follow the K.I.S.S. philosophy. I had some spark issues last year and found that cleaning the battery terminals helped.
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Old 12-03-2012, 12:12 PM   #8
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We cleaned the battery pretty good. Definitely made a difference as far as it cranking a lot stronger, but still no spark.
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Old 12-03-2012, 03:35 PM   #9
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Quote:
Originally Posted by BenjiR View Post
well i am definitely not getting 12v even up to the coil. what and where are the MAP and TPS?
and yes, i swapped everything i can think of over: whole distributor assembly that goes into the cam, the coil, throttle body assembly.
If the distributor is off then it will not start. You need to get #1 cylinder to TDC (Top Dead Center) on the compression stroke and then align your distributor. TDC can be found on your harmonic balancer (in case you did not know that) and remove #1 plug and place a finger over the hole to check for the compression stoke while you turn over the engine (by hand). You will feel air pressure against your finger. Once that is done, mark #1 on your distributor with a marker and pull the cap. Your rotor should be facing the mark. If it is off then you need to pull the dist. and re-install it.
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Old 12-03-2012, 05:14 PM   #10
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Would it not even spark if its not in line properly?
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Old 12-03-2012, 05:41 PM   #11
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Not according to the guy in the link I posted before.

I read a long article on the importance of the cam/crank sync. Basically in the Jeep referenced it would not start. The distributor actually gave 2 sparks & stopped because the sync was not what the PCM (computer) expected & shut it down. I think that also threw a code so that may not be your problem but it shows how everything has to be right to get them to start.
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Old 12-03-2012, 06:14 PM   #12
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Hmm, before we replaced the old distributor with the new one we placed both rotors at the 11 o'clock position and then did the swap, so they should be in line?
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Old 12-03-2012, 08:54 PM   #13
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Well the distributor may not be the problem. It won't explain the high voltage codes. Still the FSM gives a detailed method of making sure it is indexed correctly. Not hard to check to be sure. The fact that there is no adjustment possible once installed tell you that is needs to be in there precisely.
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Old 12-10-2012, 01:03 AM   #14
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Is the crank position sensor hooked up and working?
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Old 12-10-2012, 02:39 AM   #15
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Using a spark tester or a screw driver, disconnect one of the plug wires and ground it.
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Old 01-28-2013, 12:13 PM   #16
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Took it to a mechanic and said I needed a new computer. Should I get a '97 or a '98, and if I need the '97, what part number would I need?
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Old 04-12-2013, 08:36 AM   #17
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Final update. It was the grounding pin coming out of my old computer, so the dealership was able to jumper to another ground wire and got it running!

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