My truck was parked for a couple weeks in an extremely wet and humid environment. Definitely not the first time though.
It started up right away and drive just fine, but going up steep hills is started sputtering/misfire. When letting off the gas a little bit it helped a little, but too low of rpm’s the same thing. It kinda feels like a clogged fuel filter, but I put in a new fuel filter and fuel pump not that long ago. And also, you know how a fuel filter runs alright at first if it’s been parked for a bit, but then gets worse as you’re driving, if anything this seems to be doing the opposite.

When it’s doing it really bad, the check engine light was flashing, but at the top of the hill, the light wasn’t on, and no codes. I even checked for codes while it was flashing on a different hill, from my scanner, and it still said no codes, even as the check engine light was flashing.

Over the past year I’ve swapped out the fuel pump and filter, knock sensor and it’s wiring, cleaned injectors with new o-rings etc., new timing belt water pump, valve cover gasket.

This is a 3.4 I put in my 88 pickup, but many years ago and much more many miles ago, so it’s not an issue of the swap itself.

Id really appreciate any thoughts any of y’all might have about this.

Thanks a bunch!

-Scott

 

If a CEL lights, even if it turns off on its own, it should leave a code to read. There must be something wrong with the OBD2/ECU installation?

If it's low fuel pressure/low flow, then all cylinders will be affected, and the engine will just sort of lose power and sputter. If it's a coil/wire/injector, the engine will still run well enough on the other cylinders, just miss on 1 or 2.