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Ok, been reading and searching these codes for about 2 weeks. 2000 F150 4.2 2wd. Replaced spark plugs, wires, all O2 sensors, cleaned & tested MAS (ok), new fuel filter, and hula girl on dash. Had the dealer look at it yesterday. They said no vacuum leaks, but the fuel pump tested at 26psi continuously, and no other codes. They said that was likely the "culprit". It starts great cold, idles down nicely, but when warmed up and shut down for about 5-10 minutes, upon starting it stumbles, wants to stall, and throws the codes mentioned above after driving it for about 5 minutes. Runs ok after giving it some gas. I know everything that I've read says plenum, plenum, plenum. I've not read anything about fuel pressure causing this. What do you folks think? Change the pump for sure, but what about the plenum gaskets? Just do it?
I'm chasing the same ghosts. Mine idles high, and throws the same codes. I cleaned MAF sensor, throttle body, IAC motor assembly, and no change. Do a search on Google - there are a number of videos on a "smoke Test" which may pinpoint the leak - even if an intake manifold gasket. My next move is to take it to a shop.
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1998 SuperCab Lariat, K&N CAI, LED Halo headlights, LED gauge / temp / headlight switch panel mods
Yah well, the shop was no help. I picked up everything I need for the intake and am going to just changing it out. The tank straps get changed on recall tomorrow, then I'll change the fuel pump and go from there.
Having the same codes on my '03 4.2. Please let me know if the intake gaskets fix the problem or if it is something else. Low on funds right now so a definite direction to start from would help a lot.
Let me know what YOUR dealer comes up with. I have to go in for the same recall, and don't want them to just throw parts at it - if it's something simple that we missed - or didn't find yet!
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1998 SuperCab Lariat, K&N CAI, LED Halo headlights, LED gauge / temp / headlight switch panel mods
Just a quick up date. I removed the plenum and found 3 problems. One, the actuator arm for the butterfly valves on the passenger side was of the rail and the IMRC bushing gone. 2nd, the butterfly valves on the disconnected side are seized. 3rd, the rubber vacuum line off the back plenum is cracked. Just about to go put it all back together and I'll let you know what comes of it.
RT
The fuel pressure should be between 30-45 psi (210-310 kPa). 26 does sound a little low. If the engine isn't getting the right amount of fuel, it will run lean.
Another PO171/PO174 question.....
Linear Mode
