I recently bought a 1992 Ford F150 4x4 with a 5.0 and the AOD transmission. It has about 156,000 miles on it. i have replaced the Engine oil and filter, the plugs, wires, and distributor cap. i also replaced the fuel filter and flushed the radiator. Now I have two problems sometimes when i am driving down the road, my tranny wont shift into third and fourth until i let of the gas slightly. This happens often but not always. Then when im in Over drive, and i accelerate the truck begins to bog and jerk, when i gas it a little more it will downshift and the problem goes away till it goes into fourth again,and i may need to accelerate then the cycle continues. My other problem is when my truck is idling and i turn on the air condition the truck will idle low then high then low until the truck turns off. I have to turn on the A/C while im driving, but sometimes when i turn the wheel, the truck will stall in the middle of a turn. or when i park the truck, and shift the truck into reverse or park, it will idle up and down, then die. I tried to be thourough, but i may have forgotten something any help will be appreciated.
FORD Forever
For your first problem, with the rough shifting, I would look at the tranny fluid level, and changing it and the tranny filter. Be sure to drain the torque convertor too so you remove all the old fluid out of there.
With the bogging when the A/C is on, it sounds like you have a pulley that is binding, specifically for the A/C compressor. When you turn the wheel, the power steering pump increases the demand on the system and if the A/C compressor is already having a problem, the P/S pump could push it over the edge.
However, this is complicated by the additional symptoms parking/shifting into reverse. Does it behave like that whether the A/C is on or off? If it is just with A/C, I think a pulley is still at fault. If not, you may have a third problem in which you should try pulling engine codes. See the sticky in the forum for the how-to on that.
"However, this is complicated by the additional symptoms parking/shifting into reverse. Does it behave like that whether the A/C is on or off?"
When i shifted the truck into park or reverse it would have the fluctuating idle problem, but not to the point where it would turn off, like when it has the ac on. Then i read a forum here that said to turn the throttle body set screw, so i turned it about a 1/4 of a turn, and it fixed the problem with the ac off
I would bet the IAC is stuck closed. Hey Vamp, that would explain the turning left and it die, because with the compressor running and PS pump running, thats alot of strain for a un-assited 650 RPM
What do you say vamp could it be my idle air control i hope it is as easy fix as that. this is my daily driver, and since funds are limited, i would hate to have to replace an ac compressor and still have this problem. All i want to do is get it reliable for my daily gas guzzling comute to college
I forgot to mention, when my truck starts to buck and i accelerate, it starts getting preignition for about 3 seconds before it downshifts then it goes away, i know its preignition because my ranger used to do this before i seafomed it, and blew the engine 3 weeks later. What else besides seafoam gets rid of preignition. My F150 came with a trailer brake,and a 7 point trailer plug,so i know the previous owner towed some heavy things. But it is in near perfect condition, so i couldnt pass it up.
Pull your codes and see if you are getting any faults for the IAC, or anything else. If it is bad you will. You can also try cleaning it, but if you have to clean an IAC to get it to work, it's likely you'll have to replace it a couple of weeks later anyway.
Also, you shouldn't mess with your throttle stop screw. It is possible someone before you did, but the throttle stop screw is like a last ditch safety mechanism to keep the truck from stalling if everything else fails. It forces the valves in the TB to stay open just far enough to allow air intake to maintain idle. The thing is, the procedure as written by Ford is comparable in length to the Illiad and just as wordy. If you are cranking on that screw to open the throttle body more to maintain idle, something else is likely at fault.
Your best bet is to thoroughly go over your codes and check your timing. I recommend checking the timing because I see you also mentioned you are getting symptoms of early ignition and that could be if your initial timing is off. It may not be off far enough to necessarily cause it to not run at all, but it could be when the computer starts advancing the timing as the truck warms up.
About that A/C pulley, if your timing is off and your idle is low, then like Brandon was saying, if you RPMs are low, the motor is going to have a hard time keeping up with the demand placed on it by the pumps it also turns. Hopefully something will turn up between the codes and your timing. If not and it is the compressor pulley, you can replace just the pulley or you could install and idler pulley (you'd just get to enjoy the Texas heat all summer without A/C).
ac compressors are expensive, but it is cheaper than buying bottles of cologne to try and mask the stench of sweating in this 100 degree weather here in Texas, also how do i check my timing, all i know is you need a timing light, and can i get my codes pulled from an auto parts store, i know they can do OBD II, but i dont know about these OBD I, and i dont feel safe sticking a paperclip in my connection
