I have a 1997 Ford F150 5 speed. Last summer when I drove with the AC on it started acting funny. It felt like I didn't know how to drive a stick. It bogged down, lost power or something. I took it to a mechanic. He cleaned something, and it drove fine for a few weeks. I took it back and he replaced the R & R Cam Sensor. It worked good for awhile again. I of course took it back and had the Mass Air Flow Sensor replaced. Worked great for a few months. Started messing up again, I noticed it worked better if the AC was off. Now it messes up if the AC is on or off. What could be wrong? I have spent $1,00.00 just on what the mechanic has done so far. Someone please help. I need a cheap and easy fix that will last. Yeah right, nothing these days is cheap.

 

No codes or lights?

We can only guess at some of the causes since we can't be their with diagnostic equipment.

1. Your timing could be off and firing later than it should which causes the expansion of gas in the cylinder to occur later than usual on the downstroke of the piston which would cause a loss of power.

2. Your timing is firing earlier than it should causing expansion of gas before TDC and fighting against the upstroke of the piston.

3. The spark plug(s) are not firing all the time so you are missing the power output of a cylinder. ( The engine usually runs kind of ruff when this happens).

4. Dirty fuel filter or dirty air filter.

5. Faulty air flow sensor.

These articles might get you started.

http://auto.howstuffworks.com/ignition-system1.htm

http://www.snowvalley.20m.com/bikes/pingtime.htm

 

The check engine light is on.

 

4.6L engine? Lots of miles on the truck?

Im not sure if Autozone still reads the codes for free but if you have a Autozone near you, call and see if they will read the diagnostic codes from your truck for free since you have a check engine light.

Looks like Denton is the closest one to you?

9S 511 W University
Denton, TX 76201
(940) 565-9400

The 4.6L engine with lots of miles can get EGR insuffient flow because of restriction in the EGR ports in the throttle body. If you have not changed your fuel filter or air filter for a long time (like 30,000 miles) then it could not hurt to have them changed. (you can visually inspect the air filter and don't change it if it looks good but if you are unsure of when the fuel filter was last changed then it can't hurt to change it).

 

o'reillys will read them for free also.
get the codes read and write them down. come back here and you'll get the help you need.