I have an '06 RAM 1500 4WD with the Hemi and automatic transmission. My truck is stock save for a Magnaflow catback. It has 144K on it, and I mainly use it on the weekends. Recently, I've noticed two symptoms:
Hesitation/Surging - Truck momentarily loses power, then surges forward (typically in uphill, low RPM, high load situations when the truck is just about to downshift into a lower gear). Initially, this symptom occurred most often when going over bumps. RPMs are usually between 1300 RPM and 2000 RPM, and throttle pressure is steady and light. This has been occurring for a few months now, I initially assumed that the bumps were causing my foot to jump off the accelerator pedal and then back on the accelerator.
Truck Stalls Out - Truck loses power and engine dies. Truck becomes unresponsive to throttle, RPMs hang where they are for a while, and then drop to 0 (engine stalls quickly). Sometimes the truck can be restarted by shifting to Neutral and restarting while still rolling, other times the truck can only be restarted after stopping the truck, putting it in Park, and turning the key off and then on. When I've tried to restart the truck while rolling in Neutral, it has always cranked over fine. So far, I've always been able to restart the truck after the engine dies. This symptom occurs ion uphills and downhills, at low RPM (between 1000 and 2000 RPM), and with light or no throttle.
Summer/Fall 2010 - All plugs replaced
September 2011 - Replaced EGR Valve
11/02/2012 - Oil Change (Pennzoil Platinum 5W-20)
11/09/2012 - Replaced bank 2 position 2 oxygen (O2) sensor - passenger side rear sensor with Bosch 15510 sensor.
In either situation, no check engine light has come on, flashed, etc. When the engine stalls out completely, the "Check Gauges" light comes on. In terms of frequency, I was using the truck the weekend of Thanksgiving, and it hesitated/surged about 10 times and shut off completely 8 times. (I was helping a friend clean out their old house so they could sell it, otherwise I would have driven the truck home and stopped after the first stall.)
The truck always starts up fine from a stop, idles fine, etc. All of the situations where the truck momentarily loses power and shuts down have been when the truck is being driven down the road between 25-50 MPH. I haven't taken it on the highway since the stalling started.
I noticed the hesitation/surging before the O2 sensor was changed, but has become much more frequent in the past few weeks (around the time of the O2 sensor change). The stalling occurred once a few months back before the O2 sensor change, but it's primarily been after the O2 sensor change. I used the truck all day the Friday after Thanksgiving and it cut out once at the end of the day. I used it all day that Saturday doing dump runs, and there were times where it would run without issue, and times where both the surging and stalling were occurring on a regular basis. The truck was much worse on that Saturday, it hesitated about 10 times and stalled out completely 8 times. It was worse at the beginning and end of the day (also the coldest parts of the day), but that may be coincidence.
With either problem, the truck still has battery power. The headlights/interior lights stay on, the gauges still work, etc. There is no problem with the truck turning over or starting. The truck starts up quickly (no hard starting). The gas tank had been filled in late October, and through the first 1/2 tank I didn't notice any issues. The stalling first occurred when there was about 1/4 of a tank remaining. The truck is now close to empty, as I didn't want to fill it up if the fuel pump needs to be replaced.
My initial thoughts were to do the following:
- Change the O2 sensor back to the (failing) stock one. Although the surging existed before the O2 sensor change, the stalling has primarily occurred after the replacement of the O2 sensor. I'm thinking the timing is coincidental, but given what I've been reading about the Bosch sensors on the HEMI, I'd like to elimnate this potential cause/contributor
- Check the transmission fluid level just to eliminate that as a possible cause
- Clean the throttle body and IAC valve - these seem to be common causes of the surging, although I'm not sure if they would cause the stalling
- Check the battery voltage/terminals/cables - I don't think this is the problem, but it should be an easy step
I've read through a ton of the threads surrounding this issue, and there seem to be many potential causes. Because I'm seeing the hesitation and the stalling, I'm wondering if anyone can give some feedback into what might be the more likely culprits. I'm also wondering if it makes sense to get a data logging setup or a fuel pressure testing gauge. I'm not opposed to having a shop taking a look at it, but I'd like to take a crack at it on my own first. I'm worried about a shop throwing a bunch of parts at it and not getting to a resolution, so I'm trying to eliminate some things off the list myself.
Here's the list I compiled of possible causes, based on searches of this site:
1) Bad EGR valve - Changed a year ago, no codes
2) Clean Throttle Body - need to do
3) Clean IAC Valve - need to to
4) Transmission Fluid Level - need to check
3) Bad fuel pump - fuel pressure test at port
4) Issue with the PCM and needing to execute a TSP on it - The truck had all current PCM updates as of the summer of 2010
5) Use Fuel Injector cleaner - need to do
6) Torque converter issue - possibly caused by low transmission fluid
8) PCM Reset - haven't done yet
9) ECT (Electric Throttle Control) - no codes, so I'm not sure this is the issue
10) Battery voltage/terminals/cables - will check in initial troubleshooting
12) Cam positioning sensor - I've read that the truck will stall if it loses the signal to this sensor, besides a code is there a better way to troubleshoot this issue?
13) PCV Valve - need to check/clean
14) Bad Gas -
15) Water in Gas - Run DryGas
16) Bad Coil Packs
17) EVAP Purge Valve
I'm trying to document this issue so that someone with the same problem in the future can see this problem and understand what some of the potential causes are.
Thanks in advance for your thoughts/feedback on the next steps I should take...