I have an 03 E250 with the 4.2l v6 150k miles. She runs great most of the time unless I have been cruising on the highway for about 100 miles straight. With no real warning it will start choking and have no power. It will idle and continues to run but chokes when I hit the gas.
If I pull over and shut it off for a bit the problem seems to go away for a while. I have been working out of town for the past couple weeks and this problem has popped up several times so far.
One of the first times it happened the right rear converter was glowing hot. That one already was making a rattling noise so it got hollowed out and it has been running pretty smooth since. The plan is to replace the complete exhaust after Christmas.
Work that has been done recently: new filters(air and fuel), new coil, wires, plugs, intake bolts(helped cold idle a lot), and hollowed one converter.
Kinda leaning toward either the throttle or MAF sensor.
The only code that the ecu is putting out now is p0420 for the converter.
So the short version is is it runs well unless I have been cruising on the highway for about 100 miles. Then it falls on its face unless I shut it off for about 15 min then it is good for a while. Any help will be greatly appreciated.
I have had the same issue on my 03 F150 4.2L. I tried cleaning the MAF sensor and the whole air intake system but the problem came back . So, I tried again, the same thing, good for a few minutes then back to the annoying gas cutting off .
and after a very long struggle,, one of my friends suggested to take it to a mechanic he knows.. and after two hours of diagnosis he connected the fuel pressure gauge and told me to drive the car with him .. and while driving the gauge appeared that the pressure of the fuel pump was so weak only about 20 psi and when I push more it disconnect . then he said that was an evidence of fuel pump defect, so when you turn the car off and turn it on the PCM reset all the ratios what makes the car work for a while but when you accelerate the pressure failed to send the amount needed .
After that, the mechanic disassemble the fuel tank all together with the fuel pump, then we got shocked when we discovered that the tank was so dirty and rusty what caused the pump to clogged and stuck.. then he washed the tank and cleaned it all together with the fuel rail and injectors and installed a new fuel pump but he suggested at any chance to change the tank because it might raise the same issue ..
The fuel pump is a definitly a possibility, gonna have to look more into that. Between work, weather and holidays I haven't had much time to play with it. But it is still acting about the same. Took a nap once on the highway, but ran smooth all week in city driving and smooth on the 3 hour trip home too. Hopefully I can get some further teating in this weekend and possibly a new fuel pump.
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