Mechanics

DIES AT IDLE IN PARK OR GEAR, ONCE IT HAS WARMED UP.

1997 Dodge Ram • 17,200 miles

Truck is a Ram 1500 4x4 with the 5.2 liter 318 motor.
So I've had a CEL for years that was related to the O2 sensor. It didn't affect the function of the truck, so I just left it. At the start of this winter, I drove it a bit and parked it, running, to unload. The truck died when I was inside. I started it again and parked it. Since then, I've had lots of problems with it dieing at idle, either at a stop or if I let it run long enough in the driveway. I replaced the Air Idle Control Valve (AIC), removed and cleaned the throttle body, replaced the PCV valve, the breather element and the air cleaner. There is no EGR on this truck. Last year, maybe the year before, I replaced spark plugs, ignition coil, spark plug wires, battery and alternator. I've had the fuel pump replaced 3 times now, most recently last summer. I also have checked for vacuum leaks using both carb/choke cleaner and an open propane tank and found no leaks. I replaced both O2 sensors, pulled the battery to clear the CEl and have not had a CEL since. I have checked with a scanner and there are no codes, no pending coded, the O2 voltage is fluctuating like it should, almost towards the Rich end of the scale. The TPS is showing throttle changes and the idle RPM is around 730. I've used an infrared thermal scanner to check the exhaust headers and two are much cooler than the rest, leading to a thought it might be running rich on those cylinders, or there is incomplete combustion. Since I've pulled the batter, I've driven over 50 miles and have tried the highway speed, off the gas/no brake for 7 seconds for no luck. The only think I think I can try next is to replace the TPS, or to just sell the darn thing. Any thoughts? I tried to put a ton of info in this post since I've done so much to it.
Avatar
ShooterAMG
February 6, 2012.




Have you looked for vacuum leaks? I know that sounds too simple, but that can do it.

When it dies-does it start right back up with no delay

Check the TPS closed and WOT voltages also check/monitor the fuel pressure-

Tiny
Rasmataz
Feb 6, 2012.
Thanks for the replies guys.

I did test for vacuum leaks, but didn't find any. That certainly doesn't mean that there aren't any, but I didn't find them. I haven't bought a vacuum tester and installed a T to test the actual vacuum draw.

To answer rasmataz' question, it does start right back up with no delay. Usually I have to keep giving it some gas to prevent it dying. I will say that occasionally, when it is doing this, if I come to a stop VERY slowing, it will keep running.

Instead of checking the TPS voltages, is it easier to just replace the TPS? It's very easy to get to, and I've pulled it once when I cleaned the throttle body. I will have to buy a gauge to check fuel pressure.

Tiny
ShooterAMG
Feb 6, 2012.
I would check to see if the IAC is working too.

I have to assume the IAC is working since it was replaced. I guess I could check it somehow by checking voltages I suppose.

Tiny
ShooterAMG
Feb 6, 2012.
Remove it from the throttle body. Have someone switch the key from off to on a few times. The pintel valve should move. Check that. You may not be getting power to it.

Great, thanks again guys. I'll check it this weekend. Temps dropped again and I"m less inclined to wrestle with it in the evenings. Someone else, friend of a friend, is asking about my trans fluid. He must think it's too thick in this cold weather and maybe is stalling at idle. Think this is too far fetched? To me, this guy is hearing hooves and is thinking Zebras not horses.

Tiny
ShooterAMG
Feb 7, 2012.
The trans fluid would't cause that.
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