I just posted a request for mechanic recommendations, and I figured I may as well see if anyone here can help diagnose my truck issues.
It's a 1994 F-150 4x4 with the E4OD transmission and 216K miles on the original 5.0 engine. It idles perfectly and runs fine for short drives of 10-20 miles. The problems start on longer drives. A few years ago I drove from Tulsa to OKC to meet an OSA member, and about halfway there the engine started to bog and the CEL came on and I seem to remember hearing some pops like a backfire but up under the hood . After a few seconds it suddenly surged til I lifted off the gas, and then seemed to return to normal. The CEL also went off. This happened repeatedly the rest of the way to OKC, with longer duration and increasing frequency. After nursing it to the meeting, I let it cool down completely. Everything I could check looked fine, so I started her up and she purred like a kitten. On the way home the same thing happened and I felt lucky to make it without needing a tow.
It's frustrating because it idles smoothly and runs good even after the engine temps come up. The problem doesn't seem to crop up unless it's driven at least 40-50 miles without stopping to cool down. The only code I remember getting was for the O2 sensor, which has been replaced a couple of times.
I've replaced the following so far:
Fuel Pump, Coil, Distributor, Plugs and Plug Wires, Ignition Control Module
Sensors: O2, Throttle Position, Coolant Temperature
EGR and IAC Valves looked good but haven't been replaced
Can't find any leaks in the vacuum lines (using ether and propane)
Anybody have any ideas? I think it's emissions related, but I can't find any issues there. Two mechanics thought they fixed it, but unfortunately both were wrong. I'm still looking for a mechanic who knows this particular model inside out, particularly the emissions control system.
It's a 1994 F-150 4x4 with the E4OD transmission and 216K miles on the original 5.0 engine. It idles perfectly and runs fine for short drives of 10-20 miles. The problems start on longer drives. A few years ago I drove from Tulsa to OKC to meet an OSA member, and about halfway there the engine started to bog and the CEL came on and I seem to remember hearing some pops like a backfire but up under the hood . After a few seconds it suddenly surged til I lifted off the gas, and then seemed to return to normal. The CEL also went off. This happened repeatedly the rest of the way to OKC, with longer duration and increasing frequency. After nursing it to the meeting, I let it cool down completely. Everything I could check looked fine, so I started her up and she purred like a kitten. On the way home the same thing happened and I felt lucky to make it without needing a tow.
It's frustrating because it idles smoothly and runs good even after the engine temps come up. The problem doesn't seem to crop up unless it's driven at least 40-50 miles without stopping to cool down. The only code I remember getting was for the O2 sensor, which has been replaced a couple of times.
I've replaced the following so far:
Fuel Pump, Coil, Distributor, Plugs and Plug Wires, Ignition Control Module
Sensors: O2, Throttle Position, Coolant Temperature
EGR and IAC Valves looked good but haven't been replaced
Can't find any leaks in the vacuum lines (using ether and propane)
Anybody have any ideas? I think it's emissions related, but I can't find any issues there. Two mechanics thought they fixed it, but unfortunately both were wrong. I'm still looking for a mechanic who knows this particular model inside out, particularly the emissions control system.
