Hi all, looking for some help troubleshooting this problem. No codes are coming up except for a couple that I think are unrelated, later on that...

My Durango will bog/sputter when I try to accelerate, but only after the truck is warmed up. If it's been sitting for a while, I can drive it for about 20 minutes, or 15-20 miles with no problem. Drives great.

Then it starts to act up, but only when I accelerate. It idles fine, if I'm on the freeway coasting, it runs fine. If I put it in neutral, it revs up perfectly. I can even drive it as long as I don't give it much gas, and keep it below 20 mph.

Here's what I've tried so far.
Swapped out the TPS. No change.
Changed the spark wires and 2 of the spark plugs. I did this because I was getting a misfire on cylinder 4 and when I looked at them all 4 & 1 looked bad. Like a rusty brown color on the ceramic part. The rest looked fine. ( I probably will go back and change them all after I fix this problem)

My buddy the mechanic (Who has helped me a bunch already and I don't want to keep bothering him) seems to be convinced it's a voltage issue. Had me spray the wires and the coil with soapy water to see if there were any sparks. Nothing.

I feel like it must be a fuel/air issue, and is probably one of the sensors since it only happens when it is warmed up.

The only other thing is I did get a couple of codes. One was the misfire mentioned before, and the other was P0463, fuel level sensor. It's been doing this thin off and on where the gas gage wil dip all the way to empty, for about 3 seconds and then go back to where it was. Might do this 3 or 4 times before I take off and start driving.

Anyone have any ideas?

 

It could possibly be an air-fuel/o2 sensor since it would be running on presets until it warms up. I'd use a scan tool to monitor what it's seeing and calling for as far as the fuel mixture goes. If you don't have one a $12 bluetooth obd reader and the $5 torque app will work great.

 

Ok, I'll look into that. Wouldn't a bad o2 sensor set a code?

I've heard of the torque app, looks like it's not available for ios.
I'm seeing a few others, I'll look into those...

 

The computer would have no way of knowing if the engine is just running lean or that the sensor is just showing lean when it really isn't, so not necessarily. And I have no idea with ios apps... apple wants to be a bunch of ***** and make hardware access a pain if not impossible.

 

I got the bluetooth/wifi scanner arriving today so I'll check the o2 sensor tonight.

Mechanic buddy suggested unplugging the coolant temp sensor to trick the computer to think it's not at running temperature to see if the problem goes away after it warms up.

Thoughts on that?

 

So, I disconnected to temp sensor, let it warm up and the problem is still there, though not as bad...

I have the scanner now and have tried a couple apps, but I'm not sure which one will monitor the fuel mixture as suggested by that guy.

Any suggested apps for ios?

 

I don't think you're going to get the fuel mixture. What you're going to need to look for are the o2 sensor outputs (should be relatively sinusoidal) and the fuel trim.

 

Ok, so I have the EngineLink app.

As for o2 sensor output, I have these options:
BK 1 Sensor 1 O2 Voltage
Then also Sensors 2-4, and then
BK 2 Sensors 1-4 O2 Voltage

Then:
Short term secondary O2 trim bk 1 (and then also 2-4, and also Long term 1-4)

There's also O2S1_WR_lambda(voltage) and O2S1_WR_lambda(Current)
These actually each have O2S1-8.

I guess I can start trying each, unless you have a suggestion of which to try?

 

I'd be looking at the fuel trims. The long and short term will be telling you what the computer is calling for as far as rich vs lean.

 

Ok, so I brought it by my buddies house so he can have a look.

O2 sensor readings were fine.
Did vacuum & compression tests (because of the misfire in #4).

Vacuum was good
For compression, all cylinders were reading about 120 except for #4 was about 100, so that's not good but I don't think it's the current problem.

It's really hard to describe what this truck is doing without experiencing it yourself.
Mechanic friend was convinced it's the #4 cylinder, but I said 1 cylinder misfiring would not create this problem. Finally he drove it and had now completely changed his opinion. He thinks it's a fuel issue...

We checked the fuel pressure, and it was a solid 50psi.

I mentioned earlier the weird P0463 code, where the gas gauge will drop down to empty all of a sudden, even when it's full, and then go right back up. Could this be related? Maybe something weird in the fuel pump?

Again, this only happens after it warms up, and only when there is load/acceleration. If it's idling, or I pop it in neutral revs up just fine.
In fact on my way to his house it was plenty warmed up when I got there, but it was running fine. I pulled over and turned it off right before arriving, and as soon as I turned it back on the problem started.