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03-02-2013, 04:36 PM
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Originally Posted by jeepcherokee99
Ok so I cleaned the throttle body changed the air filter and I plan on running sea foam and changing spark plugs. What else should I do to try to increase mpg? Should change any sensors and if so which ones?
03-02-2013, 04:37 PM
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Year: 1993 YJ Wrangler
Engine: 4.0 I6
03-02-2013, 04:41 PM
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Year: 1989 Limited
Model: Cherokee
Engine: 4.0
86 Comanche alternator issue
OK guys here is the problem, Sons Comanchee with the 2.5 alt went out only displacing 4.3 volts. replaced it & new one was ok for about 2-3 wks. then battery light was coming on tested it at the back with motor running, 0.54 volts. Returned it to Advanced Auto. Did the bench test & it passed 4 times, did some digging & found out wrong alt because the original had plug input 3 wires at 12 o'clock position & the replacement they gave had plug @ 4 o'clock which put the plug right against the valve cover & a ***** to install.
So I get the correct one & install, have the same problem. Voltage is either reading a 1 or like 0.5. So I figure bad ground.... ran a wire from back of the alt to the ground strap at the fire wall & still the same readings
. Also tried to loosen / tighten belt to eliminate that, still same readings of the back of the alt. I checked the 3 wires coming off the plug & red goes ties into main red coming off the back. The other 2 both tan, 1 looks to lead back to the instument cluster ittiot light. The 3rd goes to a small silver electronic box on the passenger side of the inside fender just behind the battery, don't know what it is or if it can be the cause? Please someone 
So I get the correct one & install, have the same problem. Voltage is either reading a 1 or like 0.5. So I figure bad ground.... ran a wire from back of the alt to the ground strap at the fire wall & still the same readings
. Also tried to loosen / tighten belt to eliminate that, still same readings of the back of the alt. I checked the 3 wires coming off the plug & red goes ties into main red coming off the back. The other 2 both tan, 1 looks to lead back to the instument cluster ittiot light. The 3rd goes to a small silver electronic box on the passenger side of the inside fender just behind the battery, don't know what it is or if it can be the cause? Please someone
03-02-2013, 04:55 PM
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Year: 1989 Limited
Model: Cherokee
Engine: 4.0
No, because I thought that the silver box in question was the voltage regulator. But it is internal to the alt. Checked the wires & found the red one that goes into the plug had a bare spot. So I cut all 3 wires to same length & replaced new connectors on the end that goes into the plug,
03-02-2013, 04:57 PM
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Year: 1989 Limited
Model: Cherokee
Engine: 4.0
Also forgot to say battery is pretty new installed this past September & readings are at 12.5 unless it is running ( due to no/low output from alt.
03-02-2013, 05:02 PM
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Year: 1989 Limited
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03-02-2013, 05:14 PM
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Year: 1993 YJ Wrangler
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03-02-2013, 05:32 PM
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Model: Cherokee
98 cherokee, randomly throws this code out - P1391 manufact control ignition sys or misfire. It if I leave it alone... it goes away by its self... usually when im driving. But comes again maybe a few day or weeks later.. any ideas?