Ok, so I have had this truck for a little over a year now, and it is progressively getting worse. Truck is an '02 f250 ccsb, 4x4, v-10 auto, 4.30 gear, Banks headers and y-pipe, Banks intake and exhaust. When it had 33's it would get 9-11 mpg, got the 5 star tune, and got almost 13 all hywy once. lifted it and added 35's, truck dropped about 0.5 mpg all around, not too bad.

Around summer mpg started to drop even further, but probably due to mostly city miles. Did a full tune up in September, Motorcraft plugs, plug boots w/ dielectric grease, new Bosch O2's, new fuel filter, cleaned the filter and re-oiled, cleaned maf, cleaned throttlebody and replaced pcv valve. Took a trip to Norther california towing the open car trailer with my Mustang, got 11.2 mpg running at 75-80 mph, not bad. Then mpg steadily started to drop.

When it got into the 30's in the morning, I got p1131, p1132 codes for lean condition, and have been averaging 7.5-7.8 mpg, mostly city. codes havent been back for about a month, until this morning, filled up, got 4.98 mpg last tank! Got home and the p1132 cade came back, this time indicating rich condition. What does everyone think? I am at my wits end with this thing, and the fact that it can't pull a greased string out of a cats a** when you put a load to it is super depressing. I likie the truck, but am super dissapointed with this motor. Hopefully someone can help me out.......I don't want to hate it..........

 

I'm going to ask some obvious questions, not to be rude but sometimes you can get analysis paralysis - you don't have it locked in 4 wheel drive do you? e-brake dragging? Torque converter locking up (it should be)....

Just thinking out loud...

Pat

 

Pull the MAF and inspect...if you find ANY dirt/oil it could be the aftermarket air filter. If the filter is over oiled it can collect on the MAF and cause false readings in your fuel ratio. If not, it's an easy check that can be eliminated.

 

Check your brakes to make sure they are not dragging.

 

Bad MPG and lack of power, first thing I would check for is a clogged cat.

 

All good suggestion, but I would start with cleaning the MAF again. Very common problem with aftermarket air filters....

 

^^^^ This ^^^^
Just went thru it, the only thing you are missing is pinging.

Unbolt the cat, shift it off to the side, drive around the block.
You will know in a minute if its fixed or not.
Good luck
jimmy

 

truck has plenty of power, well, the same amount that it had when I got it and tuned it. The truck has never been able to pull up to my standards (guess I should have just bought a diesel). I have cleaned the maf (3) times since oiling the filter, and in fact just pulled it and cleaned it again today, does seem to be running a little smoother now. No mechanical problems, checked the brakes, not in 4wd, no pinging, like I said, truck runs fine, just inhales fuel.

Anybody heard of an O2 sensor going bad that quickly? I know to stay with Motorcraft/Autolite for plugs, but what about O2's? I have always used Bosch, but maybe these Mod motors are sensative to the O2's as well?

Thanks for the thoughts guys, keep em coming

 

Could it be you have too much ethanol in your fuel? Not sure where you are, but here in CA, they have to have a sticker on the pumps if it contains any ethanol and what percent.

You may want to check on the internet which stations has no ethanol in your area. Give that a try and see if it helps. I don't know what else it could be or if this is even the problem. It's a simple test.

 

Check the cat.

 

I've heard the Bosch O2's are lazy in terms of switching, compared to OEM Motorcraft ones. If I were doing O2's, it would be Motorcraft only.

As for the rest of the stuff, follow what the rest of the guys are saying, do not go just changing parts.

 

Yeah, I live in Redlands in SoCal. It is my understanding that all of the blends that come to non rural areas in SoCal are all E10 anymore, per CARB regs. Just went over truck with a fine tooth comb last night, and no signs of a mechanical problem, so I will just have to wait and see. It does seem to be doing better now that the MAF is cleaned again. I realy do dislike the oiled filters.... Interesting thought on the O2's Thanks guys!

 

another intersting aside, the cherry bomb muffler that I replaced the Banks muffler with, well the red paint burned/peeled right off within the first 200 miles, any thoughts on that? I have seen that from too much fuel burning in the exhaust, and also from too lean creating the excessive combustion temps. The curious thing, with a Matco scanner, none of the sensors seem to be out of the ordinary. Just throwing it out there

 

What do the fuel trims look like?

 

I don't recal off the top of my head, but they all seemed to be the same, doesn't mean they are right, but they weren't all over the board. What shouyld they be approx?