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General Forums => The Mess Hall => Topic started by: jeepboy21 on March 14, 2006, 10:22:36 AM

Title: Wierd Idle and Lowered MPG, cant figure it out.
Post by: jeepboy21 on March 14, 2006, 10:22:36 AM

So about a month ago my gas mileage suddenly dropped off from about 17mpg to barely making 14mpg.(with corrected speedo)  The jeep used to idle @ about 800 now it idles anywhere from 1500-2000.  I did not do any wheeling or mods that caused this it just started happening.  I have cleaned the TB, replaced TPS, O2 Sensor, "rebooted" the computer and checked thats the sensors are all plugged in.  I have also done an oil change and new cap, rotor ,plugs since during the time this has been going on with no change.  I dont know what to do next.  Do i need to replace the IAS, MAP, AIP?  Could this be a sympton of a craked exhaust manifold?  please help.  thank you.

Title: Wierd Idle and Lowered MPG, cant figure it out.
Post by: Jeffy on March 14, 2006, 11:51:01 AM

You clearly have a vacuum leak someplace.  Check all the lines.

Title: Wierd Idle and Lowered MPG, cant figure it out.
Post by: jeepboy21 on March 14, 2006, 12:02:10 PM

thanks

Title: Wierd Idle and Lowered MPG, cant figure it out.
Post by: jeepboy21 on March 14, 2006, 12:50:19 PM

after looking under the hood i am overwhelmed.  should i just grab the haynes and go to it or is there a better way?  are there vacum lines that "normally" need replacing on a YJ w/ 175K?

Title: Wierd Idle and Lowered MPG, cant figure it out.
Post by: Jeffy on March 14, 2006, 01:56:31 PM

What year is the jeep?  One way to find a leak is to strap a soapy solution onto hoses.  Or you could use carb cleaner.

Title: Wierd Idle and Lowered MPG, cant figure it out.
Post by: jeepboy21 on March 14, 2006, 02:33:19 PM

sorry i forgot to give the specifics.  its a '93 YJ 2.5L, 5 spd, 4.10.