Mechanics

MAP SENSOR

1993 Jeep Cherokee

Engine Performance problem
1993 Jeep Cherokee 4 cyl Two Wheel Drive Automatic 178000 miles

How do I know if my MAP sensor is going bad and what are the tell tale signs of it going bad? My 1993 Jeep Cherokee Sport runs great until I hit the gas pedal and then it runs like it has a big hesitation in it and runs rough? Please help.
Thanks, Becky
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Riverarainbow69
November 29, 2009.



Welcome to the forum. How long since a tune-up? Use a gage and check fuel pressure. Are there any trouble codes?

A faulty map sensor can cause poor fuel economy, hard starts and stalling, poor performance. There are other issues that might cause the same thing. I'd check wiring circuits, vacuum source. You can use handheld vacuum pump on the sensor to see if the voltage readings react to the vacuum?

JDL
Nov 29, 2009.
I am going to give it a tune-up in a couple of days but it has only been a year since the last tune-up. I replaced the fuel filter already. The jeep feels like it is bucking when I step on the gas pedal but it does it worse at 45MPH. What do you think it could be?

Tiny
Riverarainbow69
Nov 29, 2009.
It sounds fuel related to me? Check your trouble codes, to see if it shows anything. You should be able to get some mil codes by cycling the ignition switch. You turn key till dash lites come on, no further. Cycle the ket on--off, on-- off, on, then the check engine lite starts flashing, you count the flashes to get the codes. Your looking for two digit codes. A code 24 would be 2 quick flashes, a few seconds pause then four quick flashes.

JDL
Nov 30, 2009.
Well, it seems you have a problem with either TPS (Throttle Position Sensor) or you have a problem with spark plug(s). Check out if you have the correct spark plugs and are properly gauged. For 93, the spark plugs should RC12LYC gauged at.035. Also, you can check if you need to replace spark plugs cables. Remove the cables and check them one by one. With each cable, check it ´s respective spark plug to see if it has scratch like marks on the sides all round. If so, replace the cables.

Other problem could be the timing. Try rev the engine at P to 3000 rpm. Slowly then fast. If there is something like hesitation, then it could be timing problem.

Tiny
Karish
Nov 30, 2009.