2001 4.6hse

both codes, plus cat and hcat monitors are INC

- New Y pipe
- new genuine sensors
- throttle body heater gasket and throttle body gasket
- airbox is clean(no nests or anything)
- new filter
- new factory spec spark plugs

checked IAC and it was all gunked up, i cleaned with almost full can of cleaner(that bad) and now codes pop up 30xs faster

my original MAF was replaced with a used one. That original MAF now actually throws codes.

USED MAF (no codes) reads: while warming up it is in the 5.6 - 6.ish range then slowly goes down until warmed up. rough idle in the 730ish rpm range

when warmed:

1.35V when I checked with multimeter.
4.2-4.5 g/s (about 15 kg/h)

also while warming if i give a light rev the rpm will stick for a sec or so. could a faulty IAC cause all of this or am I on the track of a bad maf

Thanks!

 

Injector o-rings would be my guess. Pretty common and also overlooked.

 

Clear codes and give the computer time to adapt. Had those once after just a simple air cleaner element change, popped up a couple times and eventually went away. Good luck.
......

 

thanks guys!

@jafir I read about that before. Just didn't know if it would affect the MAF readings/voltage. I'll be looking into that one for sure!

@number 9
definitely gave the computer enough time! it's been months of resetting! also (recently) it seems like my truck runs better with the MAF unplugged at idle and stop (reverting to preset values).

 

I bought a refurbed MAF and the codes came back bought a new one and I've been driving 400+ miles no code.

 

My son's 04 had both these codes, and the hose that has the red clip(hose goes to the brake booster) would jiggle around. I pulled it out and coated with RTV and stuck it back in and the codes have not returned. It could be a MAF issue, but i am inclined to believe it is a vacuum leak issue.

 

Thanks guys. I got hurt and I'm out of work, but a part of me thinks it's the MAF. I just didn't know if something else would cause the MAF voltage and readings to drop as it seems to start off normal on a cold start. My evap and both O2 monitors are INC. The evap usually comes on before the code and then my cat monitors stay INC. I got screwed over bad by a land rover guy out here that I was dumb enough to trust. So I'm tight on cash but he was telling me my MAF was fine as he was putting New O2s and a Y-pipe in after telling me the old ones were reading fine $400 and 2 cases of beer prior. I sprayed around the injectors and no fluctuation. I did do seafoam way back when as well. I will look into what you all are saying and get back. Appreciate all the input!