ok guys got a good one for you all 1997 ranger 4.0 5 speed 2wd ..... had my ranger for like 4 years... ever since i got it it had a check engine light on throwing code p0174, saying bank running lean ( forget which one it refers to ) and i changed the mass air flow and all O2 sensors, never went away, so i dealt with it for the last few years, well researching different stuff i found a article on fordfuelinjection.com that said the EGR valve pressure sensor is common to cause this problem.... ok now up until today i have always thrown p0174 and ONLY that code.... today i installed a new EGR valve pressure sensor and cleared the codes and went driving around for a bit... well after 35 miles the cel kicked back on, so i hooked up and pulled code p0174 AND p0171, both banks running lean, any ideas what could be the cause ( i ask cuz i have a pretty good supply to some near free parts for it )

any ideas is more than welcome to be tried... im just sick of seeing the cel

sorry for the long post

 

the first thing that pops into my head is what is your fuel pressure and when have you changed the fuel filter .When you start your truck if you cycled your key twice would it start better

edited info: over 4 years you obviously changed the air filter( you don't have a k and n oil air filter correct?) you run injector cleaner thru it , you checked for vacuum leaks.

 

sorry forgot to mention starts and idles perfect... plenty of power for acceleration ( dont know if i lost any pulling power ) but does start and idle perfect, fuel pressure is not a problem... i feel its going to be a sensor now, maybe thinking a mass air flow, being that i changed it but it was quite a few years ago cleaning it probably wouldnt hurt.... any other ideas anybody?

 

I have heard of intake manifold gaskets causing this issue. I think ther is a post on it somewhere on this site. Search the threads by the failure code.

 

also why would it have only thrown p0174 for years and with 1 new part suddenly throw 2 codes saying both banks running lean... sorry to keep adding to it everyone

 

BTW, my mechanic said that a slight miss could throw the same code, bad plug, wire, etc. My Ranger has had the CEL on for 1.5 years, with the same codes you are getting, and the truck runs fine.

 

ok after researching the site and running outside ( in the dark and cold) i couldnt tell about the egr valve hose if its shot or not, hafta wait til daylight to do that, no i havnt tried checking for vacuum leaks around the intake by using starting fluid technique, not a k & n air filter (never cared for them) but from what im reading it looks like these 97 rangers had a large issue with vacuum leaks, plus im going to get a can of electronic cleaner and clean my mass air flow, ill try to update tommorow sometime

 

From your very first Post I believe you said you replaced the MAF and nothing changed? I think that is why no one suggested it. but it is always a good idea to clean the MAF. They make MAF cleaner I would get that. FYI ON MY TRUCK I need a special torx to remove the maf. it has a hole in it......keep us posted

 

Keep in mind TSB 98-6-8:

Ford Truck Enthusiasts Forums - View Single Post - 97 Ranger 4.0 Misfire Under Load

 

Because intake leaks can be unpredictable. The intake leaks are almost a certainty with the 4.0L of that time period. Its a matter of how long the vehicle runs before an intake leak develops. Fel-Pro gaskets are better than the OEM ones. It could have been that only one side was effected because the intake leak was small, with time it has gotten larger so that both banks are affected.

While people have recommended the propane test or starter fluid test, I would say it detects this type of leak fewer than 1 time out of 5. The reason is that it is difficult to really get the stuff where the leak may actually be without the vapors simply being blown away.

With the engines history, combined with your history of what has already been replaced and how long this has been going on, I say its time to replace those intake gaskets. You can get them at RockAuto Auto Parts here is what you need FEL-PRO Part # MS90733

 

ok guys sorry i didnt update earlier like i said i would, but havnt had the time to even pop the hood of my truck til today, anyways going from information recieved and researched i would up cleaning my maf today, also replaced the upper intake mani gaskets ( and fixed a vacuum line i broke in the process ) bolted it all back together and took it for a 45.9 mile test drive, and so far it seems to be good news, cel did NOT come on ( usually if i cleared my codes it would be back on within 25 miles ) also when i would clear my codes in the past ( enough to get it to pass emission testing ) my reader would only give me a yellow light with 1 test flashing yet, but as of tonight it gave me a green light, first time in 4 or so years, i know 45.9 miles isnt a official victory, but so far it seems good ( the old seals were "intact" from what i could tell without close inspection, but were extremely hard and brittle, plus it did look as if you could see a "trail" where it may have been pulling air in, just a small spot on it that looked unique from the rest of the mating surface, easily overlooked if you didnt pay attention, so maybe all these years the culprit was a 5 dollar part. heres hoping for the best