03 Liberty 3.7 throwing lots of weird codes and then resets itself.

[randyre]

So, I'm stumped. Got down to 25 degrees yesterday, and not sure if temperature has anything to do with it, but started up in the morning to head home from work and it was running super rough and had no power. Pulled off the side of the driveway before I even got to the road to scan for codes and it had thrown about 10-12 codes, then all of a sudden died. Restarted and it ran smooth and went to check codes and there were none. Drove 40 miles to home, when I got home, I scanned to see if anything was pending and no codes.

Also, before it died, I didn't have time to screenshot the codes or write them down, but a few I remember were some misfire codes, and a barometer code as well as P0400 EGR which is what I was looking up when it died. Weird thing is the 03 doesn't have an EGR so why the code?

Started up later in the day and had a stumble again, checked codes and it was a bunch of misfires and a P0352 Ignition coil B primary/secondary circuit malfunction. And again, while idling it died again. Again, codes all erased by themselves and upon restart was smooth as butter. Then this morning it was stumbling again, so while it was idling, and before it could die, I erased the codes and miraculously it started running smooth again, and no codes the rest of the day?

Any ideas what in the world is going on?

 

[LibertyTC]

How many miles on KJ now?
How many miles are on your spark plugs?
Once gap on spark plugs are eaten away, it will not run properly.
The kj should have new spark plugs every 35 k miles, using NGK ZFR6F-11G gap set at .040 inch.
Coil packs are also considered a tune up item & if experiencing issues re firing, replace them.
Just some ideas where to start...

 

[randyre]

How many miles on KJ now?
How many miles are on your spark plugs?
Once gap on spark plugs are eaten away, it will not run properly.
The kj should have new spark plugs every 35 k miles, using NGK ZFR6F-11G gap set at .040 inch.
Coil packs are also considered a tune up item & if experiencing issues re firing, replace them.
Just some ideas where to start...

Thanks, 147K miles on her. Changed plugs and coils 2-300 miles ago. Didn't use NGK ZFR6F-11G, but ordered some yesterday as I heard that the 3.7 is particular to those plugs.

 

[KJowner]

Old battery? Low voltage on startup upsets the ECU.

 

[LibertyTC]

Use a Volt meter, a fully charged battery should read approximately 12.6 volts first thing in the AM.
Start Jeep & note the alternator's output voltage as well. Should be over 14.volts.
Cold temperatures can effect Jeep's battery. Find a shop with a load tester.

 

[randyre]

Old battery? Low voltage on startup upsets the ECU.

Thats kind of what I was thinking, but leaning more towards grounds or relays as the battery is a brand new 800CCA AGM battery.

I also have a Bluetooth battery tester hooked up and have used it a few times and it shows its cranking just fine.

This morning it did the same thing again and after a reset it ran just fine for over 100 miles without a code. I'll try again tomorrow while monitoring the battery with the load tester.

Today's codes were:

 

[Ksat]

The ECU will apparently cut the control signal going to an ignition coil when it suspects a problem with it. A cycling of the key or clearing of the CEL usually will restore things until it detects the problem again. Perhaps your problem is coil-related.

 

[Warpc0il]

Very similar to the issue I had last year, which was eventually tracked down to bad earths in the engine bay. Didn't have time to work out which was the problem and some were too tight/rusty to dare to try and undo to clean.
In the end I ran a new wire from the battery negative to the existing earth point on the firewall, and all the issues stopped. Even the headlights were noticeably brighter.

 

[randyre]

Very similar to the issue I had last year, which was eventually tracked down to bad earths in the engine bay. Didn't have time to work out which was the problem and some were too tight/rusty to dare to try and undo to clean.
In the end I ran a new wire from the battery negative to the existing earth point on the firewall, and all the issues stopped. Even the headlights were noticeably brighter.

I am beginning to suspect grounds as well. I also had my brand-new 950CCA AGM battery tested and it drops to 9.2V on start and is showing less than 400CCA so it was replaced under warranty, and they upgraded me to an Optima Red Top for only $50 (score!!), problem has not been as frequent, but still there, so grounds are my next thing to tackle.

 

[Johnny O]

Due to the mentioned temperature drop I'd start with the battery. As others have stated, Libertys hate dirty power.
Odyssey Extreme AGM is only way to go in my opinion.

 

[randyre]

Due to the mentioned temperature drop I'd start with the battery. As others have stated, Libertys hate dirty power.
Odyssey Extreme AGM is only way to go in my opinion.

Reploaced with New Optima Red Top, and still throws codes, just not as frequently. Plan to address the grounds to the computer after Christmas and see if that cures it.