I have a 94 dodge 1500 w\a 5.2 what would a bad map sensor do?

 

Lie to the PCM about manifold pressure, thereby throwing mixture ratio off. Running either too rich, or too lean, depending on which way it decided to lie. If it fails completely, the PCM will set a code, and turn on the CEL.

What makes you think yours is bad? What symptoms is your truck showing?

Welcome to DF!

 

It has a real bad skip to it but it's not all the time. I have changed EGR valve, fuel pump, gas cap, TPS, CPS, 2 tune ups, timing chain set, cleaned the throttle body. And a diagnostic check shows nothing.

 

Look in the FAQ section for the Technical Service Bulletin about plug wire routing. Might just be getting some crossfire there, and could be an easy fix.

Also might be an O2 sensor. Does it run better when the engine is cold, and get worse as it warms up?

 

have you done the "plenum" look down throttle body for oil.. if there a pool , the gasket/Plate between the block and the maniold needs fixed

 

It doesn't really have a spefic time when it does it. Sometime it will go 2or 3 days of runnig great and then it might do it several times a day. I have noticed it to be real bad w\ac on and towing my work trailer.

 

Cleaned the TB yesterday looked good underneath, but now the idle is higher and more eratic.

 

Check for vacuum leaks.

 

Can't find any, that's why I was curious about the map sensor.

 

did you reset the pcm after cleaning the TB. if the cleaning helped (or hurt) the IAC any, it will need pcm reset to speed up its learning curve. IAC is responsible for idle speed, but there's also some interactions going on with TPS.

disconnect neg batt cable, turn on headlights for 30 sec. reconnect.