hi all
i have a 92 f150 supercab shortbox 4x4 5.0
i just picked up this truck a couple of days ago knowing it has a few probs.
starts and idles fine, but soon as i accelerate or load it , it will run rough and puff grey smoke.
it has new fuel pumps, filters, coil. ign. mod, vac. adv., any ideas? this truck is in exellent shape and well taken care of , i have all sevice records from new.

 

How about a MAP sensor? Did it get one of those?

Sounds like either the TPS is not calibrated correctly, or the MAP sensor is going bad (or lack of vaccum to it). Puffing grey smoke could indicate unburnt fuel in the exhaust. Check the vacuum line to the MAP sensor on the pass. side firewall next to the heater hoses. Any cracks or leaks in this vacuum line will cuase the engine to run full rich (and stall, sometimes). Check all your vaccuum lines for disconnections, Including the ones going to your EGR valve and related emmisions parts.

If you do not find any missing, cracked or disconnected, go to
Autozone and have them pull the codes. Its free and even though you may not have a CEL (check engine light) on, some problems do not turn on the CEL.

DO NOT BUY PARTS YET! Bring the codes back here and the forum will help you replace the bad part. (instead of throwing parts at it, that gets expensive, or going to the stealership).

Just because the codes may say O2 sensor, it may not be the problem. Many other things can cause false sensor readings.

Come back soon,

 

thanks fishin1976 for a place to start. i`ll check out the vacuum lines. on another note i just noticed that the breather is full of oil which tells me the egr may be gone also.

whatever happend to simple carburated engines and wiring harnesses the size of a dime????

 

I think you mean PCV not EGR. The EGR will never push oil to the breather, a stuck PCV valve will though. Just take it out and clean it with carb cleaner and make sure it rattles when you shake it. Check the hoses connected to the PCV also, as they could be plugged. Change the breather filter also.

Did you check if the MAP Sensor had been replaced?

(MAP= Manifold Absolute Pressure Sensor)

 

well just by lookin at the map sensor , it looks old. i also pulled and plugged the egr vacuum line and it ran much better but still a little hesitant