MAP sensor headache !

1991 cherokee 4.0 liter 5-speed


ok so my computer is flashin at me code blah blah which is the map sensor,so I ran to tacompton and stole my buddies map off his 89 wrangler 4 banger (its getttin a blown 350) same sensor i'm pretty sure right ? ,and I know its good because his jeep ran great so I threw the sensor on and Im still gettin a map code and symptoms .

symptoms: are that some times during acceleration it kind of bogs or skips ,and at idle it runs way to low around like 350-600 rpm or somewhere at like 1000 also when you blip the throttle itll go up then run wayyyyyy down low and come up to like a steady 650 if yall need a better description just lemme know !

thanks guys for any input in advance !

The hose to the MAP sensor could be messed up in some way giving it a low vacuum signal causing your exact symptoms. Is it clogged, melted, broken, split, cracked, not plugged in somewhere?

I wouldn't be certain that the sensor you borrowed is the correct application until you verify it with a parts store application chart. It could be different.

Cruiser is right. You need to ensure that the vacuum line leading TO the map sensor is pulling good vacuum, and is not wet with fuel.

Clean the connector to the map sensor with a thorough spraying of electrical contact cleaner.

A code for a certain circuit (TPS, MAP, etc) means the entire circuit. So along with the sensor, that includes wiring, connectors, associated vacuum lines, etc......

Just had to look up the part numbers--surprisingly the 89 2.5 and 91 4.0 use the same MAP sensor per rockauto.com.

FSMs almost always suggest checking the connections and wiring. They rarely suggest just replacing a part because the fault code indicate it is suspect. This is unlike most people who feel that the code points directly to a part failure. Connections before components is a good philosophy to adopt in order to save yourself a bunch of money versus just throwing parts at your vehicle.

I got the sensor for free.99 so it didnt matter. but ill check out my hose and connections today and let yall know