09 Won't Idle, No Codes

'09 KK 160,000 miles:
My daughter was on her way home from school yesterday, and stopped at a light. When it changed and she took her foot off the brake, she said the jeep just rolled backward. It wouldn't drive forward. Long story short it got towed home. But she said the engine seemed to run fine. But when it came off the tow truck, it won't stay running at idle.

So, this morning I've been working on it, and here's what I've found.
- Engine struggles to start, and when it does it surges up and down and will die. Does not smoke, or backfire.
- Holding the throttle open at between 1500 - 2000 RPM it will run ok-ish
- Sometimes will rev over 2500, sometimes refuses even with your foot to the floor.
- No engine codes. I'm using the JScan tool, and did the deep-dive scan, still no active codes.
- Pulled each spark plug, all look fine. Dry, and gapped correctly, and look to be running fine. One maybe looked ever so slightly lean.
- Got a fuel pressure gage at parts store and tested pressure at fuel rail. Consistent 58 psi.
- All hoses look fine.
- Visual inspection of Throttle Body seems fine
- When I run the Live-Data using the JScan tool, I'm seeing just one or two miss-fires
- Here's the live data when I'm holding the throttle open between 1500 - 2000 rpm
- Barometric Pressure 15psi
- Throttle Position B - 18.43%
- Throttle Position D - 9.02%
- Throttle Position E - 4.31%
- Ambient Air Temp - 57 F
- Calculated engine load - 0.0%
- Catalyst Temp Bank 1 - 1297 F
- Catalyst Temp Bank 2 - 1297 F
- Commanded EGR - 0.78%
- Commanded Evap Purge - 0%
- Commanded Throttle Actuator - 7.84%
- Engine Coolant Temp - 148 F
- Engine RPM - 1877 RPM
- Fuel Air commanded equivalence Ratio - 1.00
- Fuel Tank Level Input - 42.75%
- Intake Air Temperature - 66.0 F
- Intake Manifold Absolute Pressure - 7.00 PSI
- Long Term Fuel Trim - Bank 1 - 0.0
- Long Term Fuel Trim - Bank 2 - 0.0
- Oxygen Sensor 1 (short term fuel trim) Bank 1 Sensor 1 = -32.81%
- Oxygen Sensor 1 (Voltage) = 0.21v
- Oxygen Sensor 2 (short term fuel trim) Bank 1 Sensor 2 = 99.22%
- Oxygen Sensor 1 (Voltage) = 0.84v
- Oxygen Sensor 3 (short term fuel trim) Bank 2 Sensor 1 = -32.81%
- Oxygen Sensor 3 (Voltage) = 0.78v
- Oxygen Sensor 4 (short term fuel trim) Bank 2 Sensor 2 = 99.22%
- Oxygen Sensor 4 (Voltage) = 0.86v
- Relative Throttle position - 5.88%
- Run time since engine start - 30sec
- Short Term Fuel Trim (Bank 2) = -12.50%
- Short Term Fuel Trim (Bank 1) = -15.62%
- Throttle Position = 17.25%
- Timing Advance = 25 DEG

I'm stumped! Any advice would be REALLY appreciated. I'm not even sure what to check next. I was able to keep the engine running long enough to put the jeep in drive and move it around the driveway a bit. So I do have drive, at least a bit. All fluids are topped and look fine. Nothing dripping (more than usual!)

I wish I could help, as I had a similar issue a couple years ago but mine was the fuel pump. I believe 60 psi for the fuel pressure is right (someone check me on that) so I am stumped too. Maybe check all the ground straps and also make sure the battery and alternator are still good. If power is low, the computers in Liberties do strange things.

lfhoward said:

I wish I could help, as I had a similar issue a couple years ago but mine was the fuel pump. I believe 60 psi for the fuel pressure is right (someone check me on that) so I am stumped too. Maybe check all the ground straps and also make sure the battery and alternator are still good. If power is low, the computers in Liberties do strange things.

Click to expand...

Thanks. Yes I thought about ground straps too, but I'll double check. Battery and Alternator seem good.

It acts just like my string trimmer does when there's a blockage in the carb. I'm wondering if if maybe there's a clogged fuel filter? Is there a fuel filter outside of the tank somewhere? Maybe loading and unloading it from the flat bed tow truck stirred up some crud? But if there were a blockage I wouldn't think I'd get good fuel pressure, right? Is it possible to get good pressure, but not good flow?

That’s really odd. I wouldn’t think you’d have good fuel pressure if the filter was blocked. The filter in the KK is part of the fuel pump assembly in the tank so not really easily serviceable.

Well, at its most basic the engine needs fuel, air, and spark. Fuel seems ok with 58 psi. What about checking the other two?

lfhoward said:

That’s really odd. I wouldn’t think you’d have good fuel pressure if the filter was blocked. The filter in the KK is part of the fuel pump assembly in the tank so not really easily serviceable.

Well, at its most basic the engine needs fuel, air, and spark. Fuel seems ok with 58 psi. What about checking the other two?

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Right, so the air filter isn't clogged, so air is getting in. I checked around for vacuum leaks, but haven't hooked up a smoke test yet.
I've had coils go bad in the past, and they have always popped misfire codes. And the JScan doesn't show any misfires. So i think the coils are firing. I guess that doesn't guarantee the plugs are sparking. But if they weren't I would expect the bad ones to be wet.

murdoc said:

Thanks. Yes I thought about ground straps too, but I'll double check. Battery and Alternator seem good.

It acts just like my string trimmer does when there's a blockage in the carb. I'm wondering if if maybe there's a clogged fuel filter? Is there a fuel filter outside of the tank somewhere? Maybe loading and unloading it from the flat bed tow truck stirred up some crud? But if there were a blockage I wouldn't think I'd get good fuel pressure, right? Is it possible to get good pressure, but not good flow?

Click to expand...

Murdoc - quick test for grounds : take a heavy jumper cable from battery negative to an accessible place on the block. Bypasses ssveral ground paths. If it clears up, you have a better idea where to look.

Re the fuel filter - nothing outside the tank on kj, so i imagine kk is the same.

58 psi should be good. But. Does the pressure stay up with key off or bleed away quickly. If it bleeds away, replace the fuel pump.

DadOSix said:

Murdoc - quick test for grounds : take a heavy jumper cable from battery negative to an accessible place on the block. Bypasses ssveral ground paths. If it clears up, you have a better idea where to look.

Re the fuel filter - nothing outside the tank on kj, so i imagine kk is the same.

58 psi should be good. But. Does the pressure stay up with key off or bleed away quickly. If it bleeds away, replace the fuel pump.

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Thank you very much for the ideas. I connected the negatives of a jumper cable to the battery negative, and one of the mounting ears of the alternator. Did not make a difference.

Started the engine and let it run a while for while by itself (no throttle input) and it finally produced codes P0172 and P0175.
I checked the fuel pressure aft 30 minutes of the engine off, and it is holding at 42 psi.

So I'm thinking it has to be injectors, right? I want to blame the O2 sensors, but there's no physical damage on them that I can see, and they all four seem to be in the same range of each other's voltage. The only other thing I can imagine is a big vaccum leak.

murdoc said:

Thank you very much for the ideas. I connected the negatives of a jumper cable to the battery negative, and one of the mounting ears of the alternator. Did not make a difference.

Started the engine and let it run a while for while by itself (no throttle input) and it finally produced codes P0172 and P0175.
I checked the fuel pressure aft 30 minutes of the engine off, and it is holding at 42 psi.

So I'm thinking it has to be injectors, right? I want to blame the O2 sensors, but there's no physical damage on them that I can see, and they all four seem to be in the same range of each other's voltage. The only other thing I can imagine is a big vaccum leak.

Click to expand...

Injectors - nope, imo. With that fancy real time data you got, check the heater circuit on upstream o2 sensors. The voltages look ok, but o2 sensors have a heater to get the catalyst up to temp to read and adjust correctly. Case in point, I had a stick lying across the road and it hopped up and clipped the downstream bank 1 wiring off. Caused only a CEL, but it was fun finding it in the winter. Pulled the connector from the mount and it melted against the exhaust and then shorted to ground.

Since o2 feeds data to the enging computer, the output of your injectors is controlled by their (o2) data. GIGO - Garbage in, Garbage out.

Fp pressure good.

Ground at alt mount, i would still rather see it on a hunk of block. Eliminating possible increased resistance due to 2 dis-similar metals AL on the block, FE on the bracket. THere are a strap ground with 2 leads on the firewall that lead to the right and left head. Mine on the 06 were cut by the ‘mechanic’ who transplanted an engine before I bought the jeep. It would not run in the rain. Funny how little stuff like cut straps Oh ! And blue painters tape to make splices on the wiring to the CPS sensor can keep a truck from running. One splash and she was done for a few hours.

DadOSix said:

Injectors - nope, imo. With that fancy real time data you got, check the heater circuit on upstream o2 sensors. The voltages look ok, but o2 sensors have a heater to get the catalyst up to temp to read and adjust correctly. Case in point, I had a stick lying across the road and it hopped up and clipped the downstream bank 1 wiring off. Caused only a CEL, but it was fun finding it in the winter. Pulled the connector from the mount and it melted against the exhaust and then shorted to ground.

Since o2 feeds data to the enging computer, the output of your injectors is controlled by their (o2) data. GIGO - Garbage in, Garbage out.

Fp pressure good.

Ground at alt mount, i would still rather see it on a hunk of block. Eliminating possible increased resistance due to 2 dis-similar metals AL on the block, FE on the bracket. THere are a strap ground with 2 leads on the firewall that lead to the right and left head. Mine on the 06 were cut by the ‘mechanic’ who transplanted an engine before I bought the jeep. It would not run in the rain. Funny how little stuff like cut straps Oh ! And blue painters tape to make splices on the wiring to the CPS sensor can keep a truck from running. One splash and she was done for a few hours.

Click to expand...

Thanks, I'll try grounding to the block tomorrow. So do the O2 sensors have the heater built in? I felt around this afternoon and did not feel anything look in their wiring, but will inspect closer tomorrow. I'll lift up the front end so I can get a better look.

I just had a P0171 code on my 4,7L Commander, a similar code to yours. Mine was lean, yours is running rich.

The problem turned out to be a faulty MAP sensor that was sending spurious barometer readings to the engine computer. It was trying to compensate for being at the wrong altitude basically, and so the air:fuel ratio was way off.

Check your MAP sensor maybe? The one in my 4.7 was a cheap aftermarket one put there by a previous owner. Go Mopar all the way when it comes to engine sensors.

murdoc said:

Thanks, I'll try grounding to the block tomorrow. So do the O2 sensors have the heater built in? I felt around this afternoon and did not feel anything look in their wiring, but will inspect closer tomorrow. I'll lift up the front end so I can get a better look.

Click to expand...

The heater is part of the sensor. Note - if your live data shows bad, still check the wiring closely. On our older jeeps, the wire can be corroded inside (green crusties) and weak but have insulation intact. Odd behavior for a jeep that was running snd now wont - just after being towed.

DadOSix said:

The heater is part of the sensor. Note - if your live data shows bad, still check the wiring closely. On our older jeeps, the wire can be corroded inside (green crusties) and weak but have insulation intact. Odd behavior for a jeep that was running snd now wont - just after being towed.

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Yes, and I think it is also odd that I'm getting rich codes on both banks. What are the odds that two O2 sensors go bad at the same time. I'm thinking it must be something higher up that can affect the whole engine at once. I think I'll start today looking at the EGR valve. Maybe it's stuck open or closed? Then move on to a smoke test looking for vacuum leaks, then O2 sensors. I've got all day to work on it today. So that's my plan of attack.

Anyone know if these are normal pressures? That would help eliminate a bad MAP sensor as a problem.
- Intake Manifold Absolute Pressure - 7.00 PSI
- Barometric Pressure 15psi

According to my local weather service, our Barometric Pressure yesterday was 30 in inches Mercury, which converts to around 15 psi. So I think the MAP sensor is ok.

murdoc said:

Yes, and I think it is also odd that I'm getting rich codes on both banks. What are the odds that two O2 sensors go bad at the same time. I'm thinking it must be something higher up that can affect the whole engine at once. I think I'll start today looking at the EGR valve. Maybe it's stuck open or closed? Then move on to a smoke test looking for vacuum leaks, then O2 sensors. I've got all day to work on it today. So that's my plan of attack.

Anyone know if these are normal pressures? That would help eliminate a bad MAP sensor as a problem.
- Intake Manifold Absolute Pressure - 7.00 PSI
- Barometric Pressure 15psi

According to my local weather service, our Barometric Pressure yesterday was 30 in inches Mercury, which converts to around 15 psi. So I think the MAP sensor is ok.

Click to expand...

I can check my 06 later and see what I get. In Maryland I am at 30.10 and falling accourding to weather.com

BIG UPDATE! First thing I did this morning was go out and remove the EGR pipe going from the EGR valve to the intake tube. Then I tried to remove the EGR valve itself. One mounting bolt (T45) was stuck and started to strip. The second bolt started moving, then broke in half down inside the block. (Because of course it did). So I said to heck with removing it, one bolt's better than no bolts. I ran test leads from the batter directly to the positive and negative pins on the EGR valve and tapped it on/off a bunch of times. It sounded pretty good and snaps on/off. Next, for the heck of it, I started the engine with no EGR pipe. Of course, it ran like poop. Then I used the finger off a rubber glove to cover the hole on the intake tube and started the engine. To my shock it ran fine! for about 10 seconds until the glove broke. I know, dumb. Luckily it didn't get sucked into the engine.

So, I re-installed the EGR Pipe, and left the EGR electrical connector unplugged. Started the engine and it ran GREAT!!! It threw a bunch of codes for the EGR being unplugged, but I drove the jeep around the block, and it was fine! Ok, then I stopped, turned the engine off, cleared all of the codes. Plugged the EGR back in, and started up again. Still running great! Just like normal. So what the heck? Did pulsing the EGR valve get it unstuck open or closed? The only other minor thing I noticed was the blue-grey gasket on the EGR pipe has a little tear in it, but I wiggled it around with the engine running and it didn't make any difference.

Going to wait a while, watch some football, and then drive around some more when my wife gets back home and can rescue me if needed. Any thoughts?

Great news so far. please keep us informed

It's great that the problem has been clarified.

ikuo78 said:

In the live data, EVAP is 0%, so the valve may have been stuck in the open position.
Or perhaps the purge solenoid valve connector had a poor connection.

Or the canister may be at the end of its lifespan.
Once the hose was removed, too much gas that had accumulated without being taken into the canister may have been released.

In any case, it's great that the problem has been clarified.

Click to expand...

Thanks for the explanation. I think the EGR must have just been stuck open and flooded the engine with exhaust gas. This evening I replaced the two gaskets on the EGR tube, sprayed some Carb cleaner down the EGR, let it soak, and actuated it some more with wires directly to the battery. Then I drove the jeep around a lot tonight. Stop and go traffic, highway, through a drive-thru. It's working perfectly. So fingers crossed, it was just a stuck EGR valve. I'll let you guys know if anything pops back up. But THANK YOU! To everyone who offered guidance!

murdoc said:

Thanks for the explanation. I think the EGR must have just been stuck open and flooded the engine with exhaust gas. This evening I replaced the two gaskets on the EGR tube, sprayed some Carb cleaner down the EGR, let it soak, and actuated it some more with wires directly to the battery. Then I drove the jeep around a lot tonight. Stop and go traffic, highway, through a drive-thru. It's working perfectly. So fingers crossed, it was just a stuck EGR valve. I'll let you guys know if anything pops back up. But THANK YOU! To everyone who offered guidance!

Click to expand...

Oops
KK has EGR.
EVAP is a misunderstanding.
I edited the above and deleted it.
Please ignore.

Found a GREAT explanation as to what was going on with my engine with a stuck open EGR valve:
What Happens when an EGR Valve Sticks Open?

So glad you found the problem. Also that you were able to fix it. The nearly free option is always preferable!