I've searched the forums and while I've seen a few threads that address each individually, I haven't come across any that deal with both as a single issue. Here's what's happening.
The truck: 94 with 243k. HG replaced at about 240. Dist cap, rotor, plugs, wires replaced at 241. EFI main replaced 50 miles ago. No known coolant leaks. Oil looks fine. Heater works. Battery cranks but is due to be replaced sooner than later.
The problem: The CEL is lighting up after prolonged driving in stop-and-go traffic. Typically this is preceded by a rough idle (engine runs fine otherwise). I've also noticed that the MPGs typically tank when this is happening. On a couple of occasions the CEL has cleared itself when I drive the truck at highway speeds shortly after starting it. What's interesting/confusing is that this only became an issue during a recent cold snap here in Denver.
Diagnostic steps so far: Checked for codes via the paper clip method. Didn't code, but the O/D light did flash 2x per second. I cross referenced the FSM. However, I'm confused as to how to interpret this. In one section it says that indicates normal operation. In another it says it could be a TSM issue. I've also run some BG44 through the system and replaced the EFI main.
I've also talked to a couple of guys on the forum to get their thoughts - both had great feedback but had never explicitly dealt with a similar situation. (From talking to them, it sounds like it could be related to the fuel system.)
Anyone here ever dealt with a similar issue?
The truck: 94 with 243k. HG replaced at about 240. Dist cap, rotor, plugs, wires replaced at 241. EFI main replaced 50 miles ago. No known coolant leaks. Oil looks fine. Heater works. Battery cranks but is due to be replaced sooner than later.
The problem: The CEL is lighting up after prolonged driving in stop-and-go traffic. Typically this is preceded by a rough idle (engine runs fine otherwise). I've also noticed that the MPGs typically tank when this is happening. On a couple of occasions the CEL has cleared itself when I drive the truck at highway speeds shortly after starting it. What's interesting/confusing is that this only became an issue during a recent cold snap here in Denver.
Diagnostic steps so far: Checked for codes via the paper clip method. Didn't code, but the O/D light did flash 2x per second. I cross referenced the FSM. However, I'm confused as to how to interpret this. In one section it says that indicates normal operation. In another it says it could be a TSM issue. I've also run some BG44 through the system and replaced the EFI main.
I've also talked to a couple of guys on the forum to get their thoughts - both had great feedback but had never explicitly dealt with a similar situation. (From talking to them, it sounds like it could be related to the fuel system.)
Anyone here ever dealt with a similar issue?
