CEL on

[PlumCrazy]

I just bought a 95 4.0 with around 120,xxx miles. I get a CEL about 20 secs after I start the truck, it will stay on until I delete it, but it doesn't always come on.

the code is P1120 MANUFACTURER CONTROLLED FUEL AND AIR METERING.

Anybody else had this? It threw a lean code a while back but I changed the fuel filter and it never came back. I already tried cleaning the MAF, any other ideas? I also checked the pressure at idle, with and with out regulator hooked up It was right where it needed to be.

 

[Rifleman]

How is the air filter? Anything nesting in the ductwork? That P1102 specifically means "MAF in range but lower than expected" on most Fords.

If nothing else, swap the MAF.

 

[PlumCrazy]

The filter isnt the best, but it is not bad enough to trip a CEL. The guy before me did leave the black cone peice of the old filter down in the air box. I took it out and it still tripped the CEL. Its was running lean before, so I am pretty sure its not a air restriction issue. I am thinking its the MAF or a vaccum leak that I can't hear. I am going swap MAFS, if that doesn't work I will probably blame the O2 sensors, and if that doest work maybe injectors or a weak fuel pump?

-plumcrazy

 

[Yellowsplash]

That code usually occurs when the MAF and O2 sensors are reading non-corresponding or intermittent values, such as an exhaust leak before the O2 sensors or a dirty MAF, etc..
Only clean the MAF with CRC's MAF Cleaner ($7 bucks at the local advance-kragen-shucks-zone).
Make sure there are no exhaust leaks before the O2 sensors. Remember that the factory didnt install exhaust manifold gaskets, so after years and thousands of miles things happen. Also, the collector bolts can be hard to get tight after many years and leaks can happen there, especially if youve had it down for a clutch job and didnt, or couldnt, tighten it up enough.

 

[PlumCrazy]

How big would a the leak have to be? there are no leaks big enough to hear. And I already cleaned the MAF with CRC MAF cleaner. I edited my first post, it was a p1120 not a p1102. The scanner said manufacturer fuel air metering, but every where else I have looked says p1120 is TP sensor. I replaced the TP sensor because I had a brand new one left over from my GF's Ranger. But I am still getting the CEL. I can start the truck and drive it around awhile with no prob, then I shut it off and restart it and bam the CEL is on again, I delete it and try shuting the truck off and restarting a couple times and it is fine. then bam out of the blue it comes on again.

-plumcrazy

 

[Yellowsplash]

A little secret....run seafoam through the brake booster line little by little to avoid stalling the engine (or worse hydrolocking it). Suck alittle in at a time to help atomize it. Once youve ingested a quarter to half of the bottle, shut the truck down. Restart it in 10 mins allowing the seafoam to remove carbon from the runners, valves, and chambers. Start the truck up and watch the smoke show....If you have smoke coming up inside your engine bay, you have an exhaust leak. It may be kinda hard to fine as the smoke will be blown around by the engine fan, but it will atleast let you know its there. Dump the rest of the can in the gas tank....good luck.