I need Help

[mlrsfdc]

I have a 2002 Jeep Sahara 6 cyl.

I had a leak from my valve cover so I replaced the gasket. While I was at it I also replaced my coil rail, oil pressure sensor, plugs, and did an oil change.

Before I did all of this it would start smoothly, one the first strike. But afterwards I am having trouble getting the vehicle to start. You have to give it gas to start as well as continue to give gas until you are running down the road otherwise it will die.

When I replaced the valve cover gasket, I ended up having to disconnect most of the electrical harnesses that were in the way as well as removing the electrical for the fuel rail. I also took loose the coolant hose that went into the top of the head.

I did not disconnect the battery prior to do this. I forgot, I knew that i should have.

Now after the jeep has warmed up and has been running for at least 5 mins it runs fine. smooth and quite.

So the question is what did I do to cause this issue.

 

[72rtchallenger]

unhooking all that electrical could have caused the problem,,if its running now when you first start it I wouldnt worry unless you have a engine code

if its hard to start you can unhook the battery to try and clear the pcm and I saw this on another forum to flash it to relearn but it may be more than you want to try

From what I read, disconnecting the battery does not clear the memory which has all the learned settings for the PCM, which means the engine should run fine and emissions should be the same as they were before the dead battery. Here is a quote from another thread where the Chrysler engineer explained the procedure for resetting the PCM memory:

"Most folks know that disconnecting the battery for 15 to 20 minutes will reset the PCM to get rid of a Check Engine Light or Error Codes stored in the PCM.

However this DOES NOT reset the Adaptive Memory Tables in the PCM. Until recently I did not know how to do this.


This procedure first came to me from the folks at Avenger. I then verified it with a phone call to a Chrysler Engineer who had called me a year or so ago to ask about my experiences with a certain part on my TJ. I figured he owned me a favor. He had to check up on this for me. He called me back a week later and did indeed verify this procedure and what it does.

To the best of my knowledge it isn’t documented in any of the FSM.



Forced Flash

This very simple procedure will Erase the “Adaptive Memory” stored inside the TJ PCM and allow a new “Adaptive Memory” to be developed.

After performing this procedure the PCM will re-learn and store into Adaptive Memory your engines performance characteristics.

[L]Disconnect the POSITIVE battery Terminal and touch it to ground for 30 seconds. (This is to discharge the PCM capacitors, which maintain the Adaptive Memory.
Reconnect the Battery Cable
Turn Ignition Switch to the “On” position but DO NOT start the engine
Turn Headlight “On”
Turn Headlights “Off”
Turn Ignition Key “Off”[/L]

Adaptive memory has now been flashed, or erased from the PCM.

When you start the engine it will be running off a set of pre-programmed tables that come with the PCM from the factory.

When you get the engine up to operating temperature the PCM will start to collect data for the “Adaptive Memory”.

The PCM will collect data for Adaptive Memory for the first 50 Warm-up Cycles.


Warm-up Cycle

A warm-up cycle happens when all of the following conditions exist.

Engine is running
A raise of 40F in engine temperature must occur ABOVE the engine temperature at start-up
Engine Coolant Temp must reach at least 160 F.


Once your engine has gone through 50 warm-up cycles in at least a 500-mile distance the PCM adaptive memory is set. It WILL NOT Change unless you flash it out and start all over again.

This procedure is vitally important for this installation as the install includes much larger fuel injectors and a lot more air being forced into the engine.

However I believe a lot of folks may find it useful on their own Jeeps.

 

[TLCJ5]

After following 72RTCHALLENGERs suggestion I think you may have to drive for about 20mins for the computer to relearn normal conditions. I've had to do that on a couple of vehicles after dead batteries.

 

[mlrsfdc]

Thank you for the feedback. I have flashed my PCM and am in the process of doing the running in order to reprogram the PCM. I will update this forum in the next week to let you know how it ends up.