I have had an issue for several months. Low gas mileage, erratic idle, smelling unburnt gas, lack of power...it's been driving me nuts. I have changed the O2 sendor, TPS, new plugs, cleaned the throttle body, checked timing (spot on), and I still get codes that tell me my truck is running very rich.

I am used to carbuerated engines. These new fangled electronic things have got me bum-fuzzled most of the time and there is my problem...I was over thinking the whole thing.

So I asked myself what would you look at if this truck was carbed? I came up with several things that do not apply to an EFI engine... except one. The air filter...yeah, that's right...the air filter. I am used to the AF sitting right on top of the engine, so it has NEVER crossed my mind to check it in this truck. I took it out and about fell on the ground. It was so dirty I am amazed that it ran at all. I went and got a Fram filter for it and installed it. Started the truck and holy cow...steady idle, no gas smell, has it's power back, and I'm looking forward to better gas mileage. I could just kick my butt for missing something so basic as this.
I'm gonna run it for a few days and check codes again...hopefully with happy results.

 

Well its awesome that it might be something as simple as that. Hopefully it all works out

 

had to chuckle while reading this because i went through a similar scenario myself ... engine running poorly, poor mileage, loss of power ... after much wringing of hands and gnashing of teeth i decided to replace the cap and rotor ... problem solved.

lesson learned : take care of the basics first ... if that doesn't do it, then start pulling codes.

 

Back in the mid '80s I worked at GM in a dyno lab. Computer controlled engines were kind of new to the techs there at that time. I came in one morning and the 3rd shift tech said an engine was making bad sounds and giving a code for a bad O2 sensor. 2nd shift had seen it first, and by the time i came in they had replaced the O2 sensor something like 4 times and the computer twice. They started it up and it really sounded terrible, like something was falling apart. The day shift tech took over and in about 10 minutes he came to my office and told me the problem, there was a chunk of metal loose in one of the cylinders. How did he diagnose it so fast? He pulled the spark plugs and found one had been smashed over. It turned out the head had broken off one of the exhaust valves, which explained the bad O2 sensor reading.

So i wouldn't say do everything basic first and then pull codes. It's so easy to pull codes you might as well do it first, it might point you in the right (basic) direction to look. But as others are saying here, don't forget the basics. Even computer controlled engines need the air filter and distributor to be working!

 

Doing routine maintenance helps prevent many problems. Never throw money(parts) at a vehicle to fix it. Code readers are cheap and money well spent. If you are not sure ask..............

 

lol @ the 'new fangled electronic things' comment. EFI has been an option in Ford pick-ups since, what, 1985?

Mike

 

Well you also gotta think some of these older guys are in recent times have either bought these things new and are now having problems or are coming from a carb setup over to efi and may only understand what basics they had during the times they would work on a carb.

 

Exactly...but old dogs can learn new tricks...with a little help.

 

Dam electronics

 

Far to true, only people who can't learn with old age are folks who don't wanna learn.

 

it is very easy to overlook something as simple as a dirty air filter.

my latest brain fart:
when i change tires, i ALWAYS change the valve stems. even if they are only 1 year old.

i fought a leaking tire on my 02 diesel for 4 months.
i went as far as taking the tire off the rim, cleaning the bead surface, and painting it with bead sealer.
it went from 60lbs to 15 lbs in 1 week to 3 weeks.
i was convinced the tire was bad, and was taking it off the rim to return it as defective.
tire on machine, and i went to remove the core stem to deflate it and the whole stem came out of the rim.
apparently when i was mounting that tire, i was distracted and forgot to change the valve stem.
put a new one in, and the tire has held 60 lbs for the past 3 months now.