P0171 "NOT Drivable" - no power/bad smell of gas

2004 Liberty 4x4 143,000 miles

First off I've read the few latest threads that were about P0171, and the Major difference is that those people could actually drive their vehicles mine won't make it 2 miles on a good try. I can't get it to go 30mph, and it will die under a load. It is impossible to start without holding pedal to the floor when warm, when cold it starts and runs good for a minute but horrible under a load. It's undrivable, it's hard to move it 6feet when warm, and doesn't want to go over 25 mph on a flat surface, stalls and dies up hills.

It originally had a P0123 (TPS), P0131(b1s1 O2), and P0171 (b1 too lean) - it had sit a few months and then I ended up with it, supposedly it ran ok before it was parked.

Both Upstream O2 sensors have been replaced, the TPS was replaced, replaced Bank 1 Injectors, Replaced Battery. since yesterday.

Now I just get a solid P0171, and there is a strong smell of unburnt gas. When checking for vacuum leaks I pulled a vacuum from the side of the intake plenum (behind Throttle Body) and it idled Better than with the hose on as if the engine needed more air and was running rich(?)

I know when the P0171 code is thrown the PCM has reached its max fuel trim compensation level which is like 20% more fuel for that bank. Im not seeing or hearing any possible vacuum leak, the map sensor throws codes if you disconnect it, the TPS values are correct real time on a scan tool, the engine reacts when unplugging and reconnecting the bank 1 coil packs, and I'm smelling ALOT of gas so skeptical about thinking it's the fuel pump, the was definitely gas and some pressure when I changed the injectors, but maybe not enough pressure (?)

The new battery died trying to restart it when it got warm, so I didn't have a chance to check fuel trims because it doesn't like to stay running long without a foot on accelerator helping it. The warmer it gets the crappier it runs. It's like it's only running on 3 cylinders - definitely have spark on Bank 1 and some fuel, and no other codes.

I plan on trying to come up with a good fuel pressure gauge - but in the meantime is there ANYBODY that has had or heard of this issue. I doubt the cat is clogged but...

The Jeep won't even make it to a gas station, and my Wrangler is all apart (literally)

Remove 6 spark plugs. I'd like to see color/condition/plug gaps. set at 040 in. Use NGK ZFR 6F-11G ONLY.
Next is IAC. Remove and clean carbon from inside port & clean or replace the IAC using Mopar part.
Definitely get a fuel pressure test/ leak down test for 15 minutes.
Is there fresh fuel or stale gas in there?

LibertyTC said:

Remove 6 spark plugs. I'd like to see color/condition/plug gaps. set at 040 in. Use NGK ZFR 6F-11G ONLY.
Next is IAC. Remove and clean carbon from inside port & clean or replace the IAC using Mopar part.
Definitely get a fuel pressure test/ leak down test for 15 minutes.
Is there fresh fuel or stale gas in there?

Click to expand...

It has fresh fuel in it , it was on E and I put in 3 gallons

I'll get a pic of plugs they are newer looking but I was suspecting spark Gap too for some reason.

Its outside and it got dark and cold yesterday, I'll have a guage today, I'll pull plugs and see what the fuel is doing -

Should I try to clean or swap MAP sensor? There is a few in the Junk yard I'm going there for right front marker light I can grab a used map and see if it would help I guess.

Used electrical parts? Bad juju. Stick with new and good name brand stuff.

Sofar the only thing "electrical" I plan on putting on it that's used is a right front marker light and I swapped 3 injectors but nothing changed - it has NEW O2s, new TPS, new battery, and 6 new NGK ZFR 6F-11GI plugs I bought today but didn't have a chance to do anything to it yet

I would consider popping a used OEM Map in it just to see what happens at this point -

and I already priced a good fuel pump just in case... I haven't been able to check fuel trims or fuel pressure but I did locate a good pressure gauge for tomorrow I guess.

I hope this Jeep isn't a waste of time

carcollector said:

Sofar the only thing "electrical" I plan on putting on it that's used is a right front marker light and I swapped 3 injectors but nothing changed - it has NEW O2s, new TPS, new battery, and 6 new NGK ZFR 6F-11GI plugs I bought today but didn't have a chance to do anything to it yet

I would consider popping a used OEM Map in it just to see what happens at this point -

and I already priced a good fuel pump just in case... I haven't been able to check fuel trims or fuel pressure but I did locate a good pressure gauge for tomorrow I guess.

I hope this Jeep isn't a waste of time

Click to expand...

Sounds like you are on the right track.

Dont get discouraged, but kj's are notorious for electrical gremlins. You can waste a bunch of money chasing codes and swapping stuff.

Here is the scoop:

These are old rigs. Stuff happens. Often simple stuff that looks like something else.

Trims maxed on 1 bank only may point to a vacuum leak somewhere. Think about it. Car is used to seeing a fixed amount of air. Computer injects accourdingly. If computer now sees lotsa air. Now dump a lot of fuel to compensate. Maxed fuel trim that bank.

Or

A bad ground or wire on that circuit o2 sensors. Yeah, a ground, partially corroded will mess with you for days.


I dont know your experience with diagnostics but an old computer driven rig like this will definitely make you either crazy or crazy sharp.

I do this as a hobby. 2 kj on the road.
But, i enjoy the diagnostics and like to understand the fix rather than throw parts.

Sounds like you have the skills and sense to work thru this.

Ok so I think I have a cam phaser issue on Bank 1(?)

The fuel trim (according to my scan tool) is +32% on Bank 1, and -32% on Bank 2 - which means the PCM is trying to balance the engine(?)

The timing is @ 28 degrees on Bank 1, it stalled before I could get a Bank 2 reading, and then it wouldn't restart.

It seems to only want to run when it is cold

After letting it run with new plugs in it it started to bog as it got warm and I could hear a noise near the Bank 1 phaser, it reminded me of how a VW VR6 engine sounds when it has a cracked plastic timing chain guide.

Not sure if there is a Phaser issue, timing guide issue, or what... There used to be a trick on those 3.7 phasers but I can't remember.

Maybe I should do a compression check before I go any further too.

carcollector said:

Ok so I think I have a cam phaser issue on Bank 1(?)

The fuel trim (according to my scan tool) is +32% on Bank 1, and -32% on Bank 2 - which means the PCM is trying to balance the engine(?)

The timing is @ 28 degrees on Bank 1, it stalled before I could get a Bank 2 reading, and then it wouldn't restart.

It seems to only want to run when it is cold

After letting it run with new plugs in it it started to bog as it got warm and I could hear a noise near the Bank 1 phaser, it reminded me of how a VW VR6 engine sounds when it has a cracked plastic timing chain guide.

Not sure if there is a Phaser issue, timing guide issue, or what... There used to be a trick on those 3.7 phasers but I can't remember.

Maybe I should do a compression check before I go any further too.

Click to expand...

3.7 don't have cam phasers

Your fuel trims are way out of wack on both banks. Each bank is independent from the other, so there won't be any attempt for one bank to "balance" or compensate for the other, though I can see what would make you think that given the numbers you got.

I actually had very similar numbers to yours in my kj- diametrically opposed trims at the extreme ends- with similar driveability issues and the problem turned out to be bad O2 sensors. I know you said you replaced yours, but it's imperative with the KJs that you use NTK brand sensors, which are actually OEM. Chrysler uses a somewhat unique voltage bias on their vehicles (to handle the O2 heater monitoring, I've heard)) and most other sensors will not work properly, even if the another manufacturer or auto parts store says they will.

An engine that runs good only when cold can be a classic symptom of bad O2s, btw. The PCM ignores data from the upstreams until the engine is up to temperature. Once warmed up, the mis-reporting sensor(s) screws everything up.

If you don't want to go through the the initial expense of buying NTKs. unplug both upstream O2 plugs and see how the car drives. Unplugging them should force the vehicle into open loop where it runs on the same pre-programmed MAP that the PCM follows when the engine is cold.

If possible, try to keep driving to a minimum until you get your problem figured out as cat damage will occur with trims like that (if you live in a state where that could be a problem, at least).

WELL the issue was mechanical... From the engine dumping excessive fuel into Bank 1 due to a bad O2 sensor, the carbon in the cylinders caused the rings to stick or "seize". I probably could clean it all up and reinstall but am going to replace the rings on Bank 1 WITH THE ENGINE IN THE VEHICLE. It wasn't impossible to get those pistons out without removing engine BTW

Ksat said:

Your fuel trims are way out of wack on both banks. Each bank is independent from the other, so there won't be any attempt for one bank to "balance" or compensate for the other, though I can see what would make you think that given the numbers you got.

I actually had very similar numbers to yours in my kj- diametrically opposed trims at the extreme ends- with similar driveability issues and the problem turned out to be bad O2 sensors. I know you said you replaced yours, but it's imperative with the KJs that you use NTK brand sensors, which are actually OEM. Chrysler uses a somewhat unique voltage bias on their vehicles (to handle the O2 heater monitoring, I've heard)) and most other sensors will not work properly, even if the another manufacturer or auto parts store says they will.

An engine that runs good only when cold can be a classic symptom of bad O2s, btw. The PCM ignores data from the upstreams until the engine is up to temperature. Once warmed up, the mis-reporting sensor(s) screws everything up.

If you don't want to go through the the initial expense of buying NTKs. unplug both upstream O2 plugs and see how the car drives. Unplugging them should force the vehicle into open loop where it runs on the same pre-programmed MAP that the PCM follows when the engine is cold.

If possible, try to keep driving to a minimum until you get your problem figured out as cat damage will occur with trims like that (if you live in a state where that could be a problem, at least).

Click to expand...

I installed a Napa O2 but the damage was already done... Seized engine rings caused by excessive carbon.

Thanks for updating on the situation and sorry to hear about the problem it caused. Excessive fuel in the cylinder can also cause fuel 'wash,' which can cause not only damage the rings and piston, but the cylinder wall as well. You may want to inspect the bore 1st before proceeding with the repair.

Also keep in mind, you may have issues with the cat (if that's a concern for you) after running so lean and rich on the respective banks. When I had the same fuel trim extremes as you described earlier, bank 2 cat ended up crapping out on me.

Ksat said:

Thanks for updating on the situation and sorry to hear about the problem it caused. Excessive fuel in the cylinder can also cause fuel 'wash,' which can cause not only damage the rings and piston, but the cylinder wall as well. You may want to inspect the bore 1st before proceeding with the repair.

Also keep in mind, you may have issues with the cat (if that's a concern for you) after running so lean and rich on the respective banks. When I had the same fuel trim extremes as you described earlier, bank 2 cat ended up crapping out on me.

Click to expand...

The cats seemed ok according to the data stream and I blew air through the exhaust manifold and air rushed out the exhaust pipe so it doesn't seem clogged.

I'll find out today I just need to set timing and throw the front of engine back together.

The cylinder walls were beautiful and not out of round, no scratches, no issues.

I don't recommend this fix to anyone who hasn't done something like this before, and people who get frustrated and throw wrenches should just swap engines it's easier than re-ringing a Jeep LIBERTY with the engine in the vehicle.

But as you can see once you get the oil pan out of the way it's accessible, but the engine has to be rotated left and right to get to the rod bolts so zip tie your timing chain good before you try it, and don't be scared

It will be all together tonight I let you guys know how it ended. I didn't swap the rod bearings so I'm a little nervous.

The Jeep runs perfect now BTW - when I first fired it up I had some misfires and wouldn't hold an idle, but after 5 runs to operating temperature keeping rpms on it ir smoothed out - after a short drive it ran very very good, holds perfect ,idle even with AC on, can do doughnuts on pavement and has more power off the line than a Jeep JK.

I'll delete some photos and try and post a video. The only thing that scared me a little at first was what must've been spark knock(?) When it had misses and sounded like a rod knock. It also had ALOT of oil coming out exhaust at first but it all came around and started purring after burning the $5 of fresh gas I put in from a can (was on E)

NO check engine light, no misfires, no smoke from tail pipe - gonna do an oil change add gas and go shopping in it and see what happens.