Driving down the interstate at about 70mph, the engine light came on and the truck is shuddering. It won't accelerate and at traffic lights, it idles extremely rough. Stopped by an AutoZone, but their ODB reader would not talk with the ECM. I am taking it to the dealer in the morning. It is not bad gas, I have already used 1/2 tank with no problems. Used Amoco gas in it. Any ideas?

 

sounds like electrical failure of some component. Possible ECU failure. Not withstanding some total mechanical failure of something in the engine. Bad cyclinder etc would tell the ECU to go to limp mode...could be anything basicly Don't worry, warrenty work is cool!

 

Could be anything but the engine goes into limp home mode for cooling problems right???
The dealer can fix anything!!! AND ITS FREE!!!!

 

I've been experiencing a rough idle as well when Im sitting still for long periods of times such as at a car wash..

 

Thumper i dont think your truck is in limp home mode lol.

 

My '04 used to do that occassionally. To solve imemdiately, I would take off the fuel cap and twist it back on. But the permanent solution is to reflash your PCM....

 

The problem was the #6 injector stopped working. They also flashed the PCM to fix the throttle lag and the AC not always coming on (Still hesitant about the PCM controlling it). I asked about the very apparent rear end clunk and it is normal of course. Well anyway, it is running much better.

 

that's good, even though they want you too think the clunk is
normal

 

I had something similar happen. My truck went into "Failsafe Mode". I called my dad about it and he asked if my truck was overheating. It wasn't...it had only been running for about 30 seconds. I pulled over and turned it off and all went away for about a week. Turns out it was a sensor that was bad. Failsafe shuts down a couple cylinders and it does run a little rougher with alot less power. All is good now though.

 

same problem twice...replaced throttle body. Problem fixed.

 

Limp mode???? I would recomend Viagra.

Joe

 

Every once in a while my trucks idle would dip below 500 rpm at a stop light, shutter then die for no apparent reason, i took it in and they ran tests but came up with nothing. It has not done it in quite a while (knock on wood) but i found the best thing to do was put it in park, turn off the key and restart it. It was like re booting the computer and ran fine after that. I should note that i did quit using Arco (cheapest fuel around here) and the problem so far has gone away).

 

thumper, thats mother nature telling you to stop polluting our damn planet. hell, with gas prices this high, i shut mine off in drive thru's

 

Thats what it is? Hell every time it does it, I just rev it up to smooth it out.