Novak Conversions Jeep Wrangler TJ engine mounts

2006 Rubicon 4.0: Codes P0171 and P0174

Beach Life

New Member
Original poster
Joined
Nov 14, 2024
Messages
3
Location
Orange Beach, AL
Hi, This is my first post and I really need help with my 2006 Rubicon 4.0.

CODES: P0171 AND P0174 FUEL SYSTEM LEAN

Issues
  • Rough idle
  • Misfires / Backfires
  • Stuttering / hesitation while stopped
  • Power loss while driving over 50 mph
  • Will not start after it’s been running for awhile
Repairs
A very trusted mechanic said it was the PCM. So, I replaced it and I'm still having issues. He suggested something was getting too hot and sending the codes.
So, I started going down the list of possible causes and replaced several items.

Re-installed my PCM

Replaced
  • CRANKSHAFT SENSOR
  • MAP SENSOR
  • AIR TEMP SENSOR
Issues that have improved
  • Rough idle
  • Misfires / Backfires
  • Will not start after it’s been running for awhile

Issues that have gotten worse or the same
  • Stuttering / hesitation while stopped
  • Power loss while driving over 50 mph

The crazy thing is that it does "ok" when driving during cooler temperatures or the rain.
Once I'm on roads that are warmer, the power loss increases.

Here is a list of all parts replaced:
DATEPART
08/07/24O2 SENSORS
10/11/24FUEL PUMP
10/11/24IGNITION COIL
10/11/24SPARK PLUGS
11/01/24TSTAT
11/01/24COOLANT TEMP SENSOR
11/07/24CRANKSHAFT SENSOR
11/08/24PCM
11/12/24PCV ELBOW, GROMMET
11/12/24MAP SENSOR
11/12/24AIR TEMP SENSOR
 
06 PCMs are garbage. If your mechanic put back in a stock PCM, it may still be your problem. Only known fix is an adapted PCM from @Wranglerfix for PCM issues on 05 and 06.

Have you checked the mini cats to see if they have melted, or blown out and clogged the cat on the skid?

Has the OPDA gear been inspected?

Clean the throttle body, particularly the slot that sends air through the IAC for idling.
 
Based on the parts changed, no live data, and assuming all parts are quality OEM equivalent:

Check for vacuum leaks (smoke test preferably, brake cleaner, water bottle, etc.)

Injector balance test (although the fact that it’s on both banks makes this unlikely)

I’ve also seen a jumped tooth on the timing chain cause similar issues. It would run, but run like crap and throw lean codes. Again, all of this is assuming that the parts you replaced are quality. Can’t say that enough.
 
Yes.

You can get live ODB data from something as simple as a $30 Bluetooth ODB adapter and the free Torque Lite app.

However if you discover you need to sync the sensor in the ODBA you will need a more sophisticated scanner.

Looking at PIDs...those are the days points...like fuel trim, O2 sensor voltage...help immeasurably.

-Mac
 
Hi, This is my first post and I really need help with my 2006 Rubicon 4.0.

CODES: P0171 AND P0174 FUEL SYSTEM LEAN

Issues
  • Rough idle
  • Misfires / Backfires
  • Stuttering / hesitation while stopped
  • Power loss while driving over 50 mph
  • Will not start after it’s been running for awhile
Repairs
A very trusted mechanic said it was the PCM. So, I replaced it and I'm still having issues. He suggested something was getting too hot and sending the codes.
So, I started going down the list of possible causes and replaced several items.

Re-installed my PCM

Replaced
  • CRANKSHAFT SENSOR
  • MAP SENSOR
  • AIR TEMP SENSOR
Issues that have improved
  • Rough idle
  • Misfires / Backfires
  • Will not start after it’s been running for awhile

Issues that have gotten worse or the same
  • Stuttering / hesitation while stopped
  • Power loss while driving over 50 mph

The crazy thing is that it does "ok" when driving during cooler temperatures or the rain.
Once I'm on roads that are warmer, the power loss increases.

Here is a list of all parts replaced:
DATEPART
08/07/24O2 SENSORS
10/11/24FUEL PUMP
10/11/24IGNITION COIL
10/11/24SPARK PLUGS
11/01/24TSTAT
11/01/24COOLANT TEMP SENSOR
11/07/24CRANKSHAFT SENSOR
11/08/24PCM
11/12/24PCV ELBOW, GROMMET
11/12/24MAP SENSOR
11/12/24AIR TEMP SENSOR

FWIW, when I had this issue on my 2005, it was a vacuum leak at the side of the intake manifold (boot plug came off). I'd ensure those hoses and lines are connected.

You can also run a smoke tester that uses shop air to find cracks that only cause issues under +/- pressure.

Screenshot of my codes from that time:


Screen Shot 2024-11-14 at 2.01.01 PM.png
 
CODES: P0171 AND P0174 FUEL SYSTEM LEAN PROBLEM RESOLVED

3 weeks later, 3 different mechanics, over $2,000, and multiple times sitting on the side of the road broke down
I'm happy to say the problem has been resolved.

For the stuttering / hesitation while stopped it was the CAMSHAFT SENSOR.
The power loss was due to a DEFECTIVE FUEL PUMP installed 4 weeks earlier causing the fuel pressure to drop to 25 psi.

Thanks for your help and to this forum. I've learned so much about my JEEP.
 
CODES: P0171 AND P0174 FUEL SYSTEM LEAN PROBLEM RESOLVED

3 weeks later, 3 different mechanics, over $2,000, and multiple times sitting on the side of the road broke down
I'm happy to say the problem has been resolved.

For the stuttering / hesitation while stopped it was the CAMSHAFT SENSOR.
The power loss was due to a DEFECTIVE FUEL PUMP installed 4 weeks earlier causing the fuel pressure to drop to 25 psi.

Thanks for your help and to this forum. I've learned so much about my JEEP.

Glad you are all good now. Thanks for sharing the fixes.
 
I’m piggybacking on this thread instead of starting a new one.

I have a 2005 Wrangler unlimited and very occasionally I would get a sputtering start after driving, shutting it off, going into a store and coming out within a few minutes. But it always corrected then ran properly.

Normally it runs perfectly, no issues starting but today with the same circumstances of a warm engine, and a 10 minute shutoff at a store, when I started it it not only sputtered but would not start and threw the P0171 code. I tried for a few minutes and it kept sputtering but wouldn’t correct itself. So I sat for about 10 minutes and tried again and this time it sputtered a bit then corrected and started running properly.

It seems very specific, compared to other people code issues, and seems heat related perhaps.

Any suggestions. Thanks.
 
I’m piggybacking on this thread instead of starting a new one.

I have a 2005 Wrangler unlimited and very occasionally I would get a sputtering start after driving, shutting it off, going into a store and coming out within a few minutes. But it always corrected then ran properly.

Normally it runs perfectly, no issues starting but today with the same circumstances of a warm engine, and a 10 minute shutoff at a store, when I started it it not only sputtered but would not start and threw the P0171 code. I tried for a few minutes and it kept sputtering but wouldn’t correct itself. So I sat for about 10 minutes and tried again and this time it sputtered a bit then corrected and started running properly.

It seems very specific, compared to other people code issues, and seems heat related perhaps.

Any suggestions. Thanks.

I would confirm that you don't have a vacuum leak. Check the hoses to and from your intake manifold.

Might also have a fuel pressure issue.

It could be heat soak, but it's odd that it would begin at this time of the year. You have a WF otherwise I would have said you might need one.
 
Update your forum profile with that info!

-Mac

That was your helpful advice?

I've received lots of helpful advice from the 2004-2006 computer issues, and vibration issues due to lifts, on this site, but your's I wouldn't rate up there as much.
 
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Novak Conversions Jeep Wrangler TJ engine mounts