Bizarre Jeep Starting issue - JeepForum.com
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post #1 of 63 Old 05-09-2020, 02:51 PM Thread Starter
Marty86
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Bizarre Jeep Starting issue

I'm helping a friend out by replacing the 4.0 in his 2000 Jeep Wrangler. He found a 2006 from a wrecked one, everything matched up and so I dropped in the '06.

Through a series of trying to eliminate why this thing cranks strong but doesn't start, I have done the following:

Replaced:
-Crankshaft position sensor (per another post, wasn't getting voltage? new one is)
-battery (possibly wasn’t bad, but this one acts stronger)
-starter (solenoid seems to have been dead, wouldn't have actuated the shaft to extend the gear)
-battery terminals (both)

Cleaned/tightened:
-battery to body ground
-Battery to engine ground
-terminals on the old battery
-unplugged and plugged back in all connections (wiggled after snap was heard of connection)
-throttle body

Tried:
-pulling belt just in case there was a load from something being seized
-seeing if camshaft position sensor was potentially 180 degrees out by putting engine at TDC and aligned via instructions in manual. (started for half a second once and now tries to start if I hold the starter longer than I should)
-check fuel at fuel rail (has fuel, have not put fuel gauge on. )
-remove starter relay and jumper to turn over engine (removes ignition from the circuit, turned over fine)
-swap starter relay with the same relays on other circuits, no change

At one point there was a P505 and that drove me to clean out the throttle body. After it was cleaned I erased the code and it has not returned.

What am I missing? Do I need to try to track down a computer to get the Camshaft Position Sensor aligned? I can't believe all of that was dead beforehand or even a short would cause that...but stranger things I suppose have happened.

Any thoughts to help me get him back on the road?

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post #2 of 63 Old 05-09-2020, 02:59 PM
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SKIM? They have different ecu's, I believe. Are you using the same one? Does the 2K have a distributor?
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post #3 of 63 Old 05-09-2020, 04:27 PM Thread Starter
Marty86
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Are they that different? All sensors (save for the one I replaced) went exactly where they were. To the computer this should be the same engine. Intake and exhaust manifolds from the 2000 went on it exactly as they were before so computer shouldn't matter. (basically I put the 2006 long block in)

The 2k does not have a distributor, it has the camshaft position sensor and is computer-controlled. You are supposed to make sure its timed to the engine oil pump, which I did with making sure it was at TDC on cylinder #1 on the compression stroke when inserted, per the manual. After you set that right, it should be good to go.
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post #4 of 63 Old 05-09-2020, 04:50 PM
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SKIM would result in starting/running as normal for 3-5 seconds and then shutting down.

Do you check the Cam Position Sensor synchronization with a toothpick or small drill bit ?

Is the new CPS a genuine Jeep part, or a crappy Chinese clone part that is out of tolerance ?

Does the 2000 and the 2006 use the same flexplate for Crankshaft Position Sensor to read ?

Have you gone over all of the wire plugs checking for bent or pushed back wire pins, and for loose connections ? Have you tested wire continuity from OBD engine sensor to PCM to eliminate the possibility of damaged wires, open circuits, or failed wire splices ?

Have you tried starting and immediately pumping/nursing the gas pedal ?


For 1996+ Jeeps, the OBD-II engine computer (ECU/PCM) re-boots, and the idle settings are deleted, when you: (1) let the battery run down by leaving the lights or radio on, (2) disconnect the battery for an extended period of time, (3) when the battery goes bad and needs replacing, (4) when the alternator is not properly charging the battery, (5) or when poor battery connections result in a voltage drop at the PCM or poor battery charging. Loose, corroded, or damaged battery cables or ground wires may also cause or contribute to the problem. A faulty Coolant Temperature Sensor may also cause similar symptoms. Testing of the CTS is recommended as part of the diagnostics. A poor ground at the ignition coil can also cause similar symptoms.

The reboot symptoms are: (1) having difficulties starting the engine without depressing the gas pedal, and (2) the engine will have a low idle and probably stall unless you keep your foot on the gas pedal. (3) The ECU will relearn the idle settings after a short period of driving and the engine will sometimes start and idle normally.

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post #5 of 63 Old 05-09-2020, 05:37 PM Thread Starter
Marty86
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Its the same key he's used this whole time so I am not entirely sure it'd be SKIM. I'll check if he has the module though.

Yes, when I mentioned the Camshaft Position Sensor at TDC, I did that. Used a drill bit.

The Crankshaft Position Sensor came from O'Reilly's. In regards to the flywheel, to my knowledge they are the same but I don't know fully. Maybe someone could tell me. Edit: as far as info on this forum and a Google search turns up, the flywheels are the same on manual transmissions 2000-2006. Anyone who knows differently, please correct me.

I have looked at all of the sensors and plugs, but I haven't tested the wire continuity from OBD sensor to PCM. Can you give me more details on that?

CTS sensor was good beforehand but I haven't checked it. I feel like that would give issues to idling, not starting, though because of it trying to set open and closed loop properly.

I checked all the grounds and it seems they are all good. (I tightened/cleaned them just in case.)

I have tried pumping the gas pedal, all though it doesn't really do much compared to how it worked with carb'd engines.

Last edited by Marty86; 05-09-2020 at 05:47 PM.
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post #6 of 63 Old 05-09-2020, 07:03 PM
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Quote:
Originally Posted by Marty86 View Post
Are they that different? All sensors (save for the one I replaced) went exactly where they were. To the computer this should be the same engine. Intake and exhaust manifolds from the 2000 went on it exactly as they were before so computer shouldn't matter. (basically I put the 2006 long block in)

The 2k does not have a distributor, it has the camshaft position sensor and is computer-controlled. You are supposed to make sure its timed to the engine oil pump, which I did with making sure it was at TDC on cylinder #1 on the compression stroke when inserted, per the manual. After you set that right, it should be good to go.
Which Oil Pump Drive Assembly (contains cam sensor), and which flywheel did you use? The '06 has different notches on the flywheel for the crank sensor. I think the cam sensor notches are different as well.

'92 Islander
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post #7 of 63 Old 05-09-2020, 07:15 PM
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Quote:
Originally Posted by Marty86 View Post

The Crankshaft Position Sensor came from O'Reilly's. In regards to the flywheel, to my knowledge they are the same but I don't know fully. Maybe someone could tell me. Edit: as far as info on this forum and a Google search turns up, the flywheels are the same on manual transmissions 2000-2006. Anyone who knows differently, please correct me.

The flywheels are not the same. The early PCM will not recognize the late (2005-2006) configuration. Neither is the OPDA also called the cam synchronizer which contains the cam sensors. Both items need to be used from the 2000 motor. Maybe some other things but those come to mind.

Here is a link that deals with the flywheels as it applies to trans swaps & has photos of the 2 different flywheels.

https://www.jeepforum.com/forum/f9/n.../#post40879683
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post #8 of 63 Old 05-10-2020, 08:39 AM Thread Starter
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Quote:
Originally Posted by Rubi4MyMrs View Post
The flywheels are not the same. The early PCM will not recognize the late (2005-2006) configuration. Neither is the OPDA also called the cam synchronizer which contains the cam sensors. Both items need to be used from the 2000 motor. Maybe some other things but those come to mind.

Here is a link that deals with the flywheels as it applies to trans swaps & has photos of the 2 different flywheels.
I used the 2000 flywheel and the 2000 cam sensor/synchronizer. Thus far the only thing that is 2006 is the block and head and their internals. Everything else is 2000.

SKIM was mentioned earlier, I confirmed there is not a SKIM system on this Jeep.
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post #9 of 63 Old 05-10-2020, 09:42 AM
jkp
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It should work.

Do you know history of the engine? Possibly a jumped timing chain.

I think it would start even if the cam sensor was off. It just synchronizes the injectors. Spark timing comes from the crank sensor.

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post #10 of 63 Old 05-10-2020, 09:56 AM
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Jumping in -

Treat this as a common no start.
What CODES are there?
Is there 12 volts at injectors?
Are the injectors pulsing - noid light makes fast easy work here.
Coil is there 12v at coil? Coil rail ground pulsing ?
fuel pressure PSI?

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 #11 of 63 Old 05-10-2020, 10:48 AM
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Quote:
Originally Posted by Marty86 View Post
I used the 2000 flywheel and the 2000 cam sensor/synchronizer. Thus far the only thing that is 2006 is the block and head and their internals. Everything else is 2000.

SKIM was mentioned earlier, I confirmed there is not a SKIM system on this Jeep.

Good. Knowing that is helpful.

Jtec is right. It needs spark & fuel first. Then after verifying that, you get into timing the spark & fuel delivery. Step by step.

Finding what is lacking will direct you to the next step.
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post #12 of 63 Old 05-10-2020, 04:49 PM Thread Starter
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No codes, although I do have a computer/code reader that can read what the computer is telling us. Anything, in particular, to look at from the sensors?

I will check voltage at injectors and grab my testing light to see if they are pulsing, as well as the coil rail. I don't have a fuel pressure gauge so I'll have to go buy one to see what it says, but I know it at least getting fuel because I can press in the Schrader valve and fuel sprays out. Obviously that doesn't tell us how much, but at least I know it's up there.
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post #13 of 63 Old 05-10-2020, 05:11 PM
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"computer/code reader" what do you have a code reader or a scanner?

Lets start, when key moved to run - does the CEL come on for @3seconds then go out?

Check the 12v at injectors and coil... we really want fuel PSI but try spraying some carb cleaner ito TB this will simulate fuel and observe if engine fires tries to start.

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 #14 of 63 Old 05-10-2020, 07:06 PM Thread Starter
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Quote:
Originally Posted by jtec View Post
"computer/code reader" what do you have a code reader or a scanner?

Lets start, when key moved to run - does the CEL come on for @3seconds then go out?

Check the 12v at injectors and coil... we really want fuel PSI but try spraying some carb cleaner ito TB this will simulate fuel and observe if engine fires tries to start.
Its a scanner. Like I can see what the O2 sensor is saying or the intake temperature, etc. Onboard diagnostics. (Its not Jeep specific, but its OBD-II.)

Let me know if I should look at anything with the scanner and I'll report back from these tests.
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post #15 of 63 Old 05-11-2020, 07:17 AM
jtec
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answer questions in post #13 and we will move on from there.

have youu used your scanner on this jeep before?
Does it communicate when plugged in ?

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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