Long crank on cold start

[macleanflood]

This is what I'm talking about....

Thread 'Using the DRB III to Calibrate a New Cam Sensor in the 4.0 Engine (2000-2006)'

Apr 2, 2023

UPDATE (5/4/2026): Per this post here, certain OBDII scan tools such as this tool here will read the phasing between the cam sensor and the crank sensor and perform the re-learn procedure without the need for a DRB III tool.

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With the demise of the OEM cam sensor, TJ owners needing to replace a faulty cam sensor will soon be left with no option other than using an aftermarket sensor. Aftermarket sensors have horrible reputations on this forum, and the intent of this thread is to present some information that may help the forum determine if suitable aftermarket cam...

• sab
• Replies: 97
• Forum: TJ Resources

• 
• 

-Mac

 

[TJ Jim]

This is what I'm talking about....

Thread 'Using the DRB III to Calibrate a New Cam Sensor in the 4.0 Engine (2000-2006)'

Apr 2, 2023

UPDATE (5/4/2026): Per this post here, certain OBDII scan tools such as this tool here will read the phasing between the cam sensor and the crank sensor and perform the re-learn procedure without the need for a DRB III tool.

---

With the demise of the OEM cam sensor, TJ owners needing to replace a faulty cam sensor will soon be left with no option other than using an aftermarket sensor. Aftermarket sensors have horrible reputations on this forum, and the intent of this thread is to present some information that may help the forum determine if suitable aftermarket cam...

• sab
• Replies: 97
• Forum: TJ Resources

• 
• 

-Mac

That was my next guess to look at

 

[sasnak]

That was my next guess to look at

i have a 1999, and does not have OPDA. I have a distributor. the cam position sensor is a round disc that sits inside the distributor and locked down with the dist cap.

 

[TJ Jim]

i have a 1999, and does not have OPDA. I have a distributor. the cam position sensor is a round disc that sits inside the distributor and locked down with the dist cap.

Does it not have to be in sync with the crank? And doesn’t the 4.0 run with the cam disconnected?
Disconnect the cam sensor and see if it starts the same.

 

[TJ Jim]

https://wranglertjforum.com/threads/how-to-test-your-camshaft-position-sensor.68487/

 

[TJ Jim]

?

 

[sasnak]

This is what I'm talking about....

Thread 'Using the DRB III to Calibrate a New Cam Sensor in the 4.0 Engine (2000-2006)'

Apr 2, 2023

UPDATE (5/4/2026): Per this post here, certain OBDII scan tools such as this tool here will read the phasing between the cam sensor and the crank sensor and perform the re-learn procedure without the need for a DRB III tool.

---

With the demise of the OEM cam sensor, TJ owners needing to replace a faulty cam sensor will soon be left with no option other than using an aftermarket sensor. Aftermarket sensors have horrible reputations on this forum, and the intent of this thread is to present some information that may help the forum determine if suitable aftermarket cam...

• sab
• Replies: 97
• Forum: TJ Resources

• 
• 

-Mac

Well after $300 of swapping parts i finally found the right one. Mass Air flow Sensor. Starts right up. Thanks for all the help on the forum.
Wanted to change the injectors anyway, so i am happy. Runs like new now.
Mark

 

[MBDIAGMAN]

Does it idle smoothly once started?

 

[GoldenGorilla]

Well after $300 of swapping parts i finally found the right one. Mass Air flow Sensor. Starts right up. Thanks for all the help on the forum.
Wanted to change the injectors anyway, so i am happy. Runs like new now.
Mark

Hopefully it's a manifold absolute pressure (map) sensor. The TJ 4.0s don't use this fancy 1990s MAF tech.

Glad it's sorted.

 

[sasnak]

Does it idle smoothly once started?

well i spoke to soon. Started right up yesterday. this morning took 3 tries like usual. Not idling smoothly like it was.
Just unbelievable. I did not disconnect the battery, will try that to see if the map needs to be updated.

 

[Mall'er]

Can you test your coil? From what I have read, a weak coil could cause the symptoms, but I really don't know.

Testing values

And did I hear a bunch of radio whine when you started it in the video?

 

[sasnak]

Can you test your coil? From what I have read, a weak coil could cause the symptoms, but I really don't know.

Testing values

View attachment 635498


And did I hear a bunch of radio whine when you started it in the video?

Well I took ground wire off for a couple hours then reconnected and stTed right up. Need to reset map i guess. I think all good. Will be in Colorado for a week. Will see when I get back

 

[sasnak]

Well I took ground wire off for a couple hours then reconnected and stTed right up. Need to reset map i guess. I think all good. Will be in Colorado for a week. Will see when I get back

 

[sasnak]

well back to the drawing board. Back from trip and took 4 tries to start. Only thing i have not changed is the IAC? Have cleaned it.
I am guessing is not getting enough gas to start. what controls the choke function when starting?

 

[TJ Jim]

Change it and see what happens. You’ve been slow about trying our other suggestions so throw some more parts at it and see if that fixes it. Wasting my time but what did you glean from the cps/cps videos posted?

 

[sasnak]

Change it and see what happens. You’ve been slow about trying our other suggestions so throw some more parts at it and see if that fixes it. Wasting my time but what did you glean from the cps/cps videos posted?

i gleaned that i am not up the the task of what that guy was doing to test the CPS.

 

[Mall'er]

How did the coil test out? Free, just a few minutes with a meter.

This will let us know if there is a weak spark on start up.

 

[sasnak]

How did the coil test out? Free, just a few minutes with a meter.

This will let us know if there is a weak spark on start up.

That turned out to be the problem. Weak spark. New Coil and starts like new. Thank you all for your help.