Intermittent stalling during first couple minutes running and bad fuel mileage.

[chooch79]

I have a 2003 Ram 4.7 2wd automatic with 80K miles. Little back story... I purchased this truck new and have always followed the maintenance schedule with Mobil 1 oils. Drove it daily for 6 years and then put it in storage for 9 years, while I was stationed overseas. Every couple years when I came home, I would change the oil and drive the gas out of the tank and refill it before I left and added Stabil. When I finally moved back to the States and got it out of storage (it had 73K miles at this point), I changed eng oil, trans fluid, diff oil, spark plugs (basic champions), PCV, air filter, and tires. I flushed the coolant, power steering, and brake fluids. It had a code for the leak detection pump, I changed that and the code cleared and it hasn't returned.

Then I figured it was ready for normal driving. First thing I started noticing was the poor fuel mileage. I know its a truck and it isn't going to get the Prius mileage, but I was expecting at least what I was getting with the same truck before storage. Before storage it was averaging 15-17 MPG, after storage it is averaging 10-12. Occasionally it would stall after startup while I was driving at slow (idle or barely above) speeds. I initially ran a couple tanks of fuel with injector cleaners. It persisted. I then cleaned the throttle body and reset the computer. It persisted. I then changed Upstream/Downstream O2 sensors, TPS, CPS, CTS, IAT, IACV, and Map sensor. I inspected for vacuum leaks with a visual and also spraying water and starting fluid around the engine and hoses. It never flagged a code, just poor mileage and the occasion stalling and sometimes it will die. It is becoming more frequent with the stalling and I'm at a loss for what I should do next. It doesn't matter if i just shut the truck down 5 minutes prior and try to start driving it will still do it. Cold/hot engine doesn't matter, but it only does it during the first couple of minutes after start up. Any suggestions? Your help is appreciated.

 

[Fast69Mopar]

What is the condition of the battery, the battery cables and the terminals?

Have you cleaned the grounds that attach to the inner fenders on both sides of the truck?

I would have a load test performed on the battery. Hit one of the local auto parts stores and have them use their equipment to test the battery.

These trucks will do some crazy things with a weak battery and poor ground connections. It will cause the PCM to lose the IAC Steps, or Idle Air Control Steps. When this happens, the PCM doesn't know the location of the IAC plunger and causes the engine to stall.

 

[chooch79]

Thank you for your suggestion. Just got home from Autozone after having them test the battery/charging system. They said my battery is 100% charged and my alternator passed the load tests. The terminals and cables have always been kept free of corrosion. I have the felt washers underneath the battery terminal cables and have the red terminal treatment spray on them. The connections at the block and on the body are still tight and don't show any signs of corrosion. By the way, my battery is only a year and half old. I replaced it when I moved back. Also, I have replaced the alternator within the last year due to the old one starting to wine (bad bearing).

 

[Fast69Mopar]

Thank you for your suggestion. Just got home from Autozone after having them test the battery/charging system. They said my battery is 100% charged and my alternator passed the load tests. The terminals and cables have always been kept free of corrosion. I have the felt washers underneath the battery terminal cables and have the red terminal treatment spray on them. The connections at the block and on the body are still tight and don't show any signs of corrosion. By the way, my battery is only a year and half old. I replaced it when I moved back. Also, I have replaced the alternator within the last year due to the old one starting to wine (bad bearing).

Good to know. Have you inspected the ground straps that attach to the rear of each cylinder head? The ground strap attaches to each cylinder head and then to a stud on the bulkhead (firewall) with a 10mm nut to hold it in place.

The next thing that I suggest is to get a scan tool hooked up to the truck. We can learn a lot about what is going on this way. One of the first things I want to look at is the cam and crank signals to help in addressing the stalling concern. Next, I want to see what the PCM is seeing from the MAP Sensor for engine vacuum.

For the poor fuel economy a quick look at the adaptive memory would give us a really good idea about what is happening with the fuel control and the AFR. The Short Term Fuel Trim and the Long Term Fuel Trim would help us in which direction we needed to go to determine what is causing the poor fuel economy.

 

[chooch79]

Just checked the ground strap that goes from the back of the left head to the back of the right head and then to the firewall. That is a pain to fully inspect! Anyway it was all good. There was some undercoating over the top of the firewall point. I took it off and cleaned it up with a wire brush and put it back down. There wasn't any corrosion and the undercoating was probably even protecting it.

I don't have a fancy OBD2 scanner. Its just one of the bluetooth ones. Today I connected it up to my laptop and did a quick drive to Autozone for the battery/charging check and then right back. The drive there was uneventful, but the drive back did have a stall. See screenshots, don't know if they will help.

You believe the two issues are unrelated? Today while I had my laptop connected up and the stall occurred, it might have been during the transition from open to closed loop. I can't be exact on that because I was trying to navigate the parking lot without crashing. While I was backing out it was open, but after I put it in drive and drove maybe 20 yards, it started stalling I checked and it was closed.


View media item 28390
View media item 28391

 

[chooch79]

Is there any recommended software to use with the cheap bluetooth OBD2 adapters to get the details that you are looking for?