Topic: have simple questions about the operating info of a jeep

[countryboy15]

I have simple questions about the operating info of a Jeep, and I couldn't find answers in the FAQ section. I have a 1991 Jeep Wrangler S I4 2.5 L with a 4.0 L throttle body and 31" goodyear wranglers. I am just checking to make sure everything is right with my jeep.

1) What is the normal rpm range for 1991 Jeep Wrangler S 2.5 L  while idling at a stop?


2) What is the normal rpm range for 1991 Jeep Wrangler S 2.5 L at 55 mph, on a road with 31" goodyear wranglers?


3) What is the normal gas mileage for 1991 Jeep Wrangler S 2.5 L with 31" goodyear wranglers


4) What is the normal operating temp with OEM factory recommended thermostat? (I think the degree is 190ish)

[b.hog]

 mine Idles at 700 (with 4.0 throttle body)

 1500 -2000 rpm 5th gear (depending on wind)

 I average 16.4 mpgs , thats highway and all playing combined

 and I think your right about the 190ish,seems thats were mine stays ,but i have e-fan, so I may be wrong.

 Hope this helps

[Sine Deviance]

1. With the 4.0L throttle body and a new PCM, my Jeep idles between 700-800 rpm.

2. At 55 mph, in 5th, you should be hanging between 2000-2500 rpm. At 65 mph, 3000-3500.

3. I have 31's and I get about 17mpg average. Your mileage may vary.

4. I'm not exactly sure. Mine hangs around 210F on the gauge. This is likely to be a little high, I may need a new thermostat. Mine could be getting stuck closed. Still, it does eventually open up and cycle.

[countryboy15]

....
  1500 -2000 rpm 5th gear (depending on wind)
....
 i have e-fan, so I may be wrong.
...

how did you get yours to run at 1500-2000 rpms?
I have the E-fan also.

1. With the 4.0L throttle body and a new PCM, my Jeep idles between 700-800 rpm.

2. At 55 mph, in 5th, you should be hanging between 2000-2500 rpm. At 65 mph, 3000-3500.

3. I have 31's and I get about 17mpg average. Your mileage may vary.

4. I'm not exactly sure. Mine hangs around 210F on the gauge. This is likely to be a little high, I may need a new thermostat. Mine could be getting stuck closed. Still, it does eventually open up and cycle.

My jeep runs about like yours

[sharpxmen]

how did you get yours to run at 1500-2000 rpms?
I have the E-fan also.

the only way to change the rpm to speed ratio is to change gears (in your axles) - there's no adjustment

[b.hog]

how did you get yours to run at 1500-2000 rpms?
I have the E-fan also.


I didnt do anything to make it run that way,it's just where it is,I also run 31's(w corrected speedo gear).But my lil yj has only got 52,000 miles on the ticker,so that may be some of it.I read somewhere that  the 2.5-ax5 manual with 410 gears @2200-2500 rpm should = 65 mph , withought galeforce winds of course.That was the main reason I changed my speedo gear after bigger tires.

[FourbangerYJ]

the only way to change the rpm to speed ratio is to change gears (in your axles) - there's no adjustment

Change tire size will also affect RPM to speed ratio.

[sharpxmen]

Change tire size will also affect RPM to speed ratio.

well, he was asking for 31'' tires - you can also deflate them, that will change the ratio too  

[Jeffy]

I have simple questions about the operating info of a Jeep, and I couldn't find answers in the FAQ section. I have a 1991 Jeep Wrangler S I4 2.5 L with a 4.0 L throttle body and 31" goodyear wranglers. I am just checking to make sure everything is right with my jeep.

1) What is the normal rpm range for 1991 Jeep Wrangler S 2.5 L  while idling at a stop?

700-750 RPM or there about.

2) What is the normal rpm range for 1991 Jeep Wrangler S 2.5 L at 55 mph, on a road with 31" goodyear wranglers?

Depends on what gear your in.  You can use the Tire & RPM applet at http://www.jeeptech.com/javaAps/gta.html

3) What is the normal gas mileage for 1991 Jeep Wrangler S 2.5 L with 31" goodyear wranglers

Stock figures are 18-21 MPG.  Keep in mind that unless you recalibrate your speedometer for those tires it will read low.  Also, keep in mind those figures where when highway speeds were 55 MPH.  Accounting for larger tires, lift and additional weight and you could be 16-18 on the low side.  Some  2.5's have recorded around 23-27 MPG on occasion but depends on a lot of other factors.

4) What is the normal operating temp with OEM factory recommended thermostat? (I think the degree is 190ish)

African or European?...   

The stock thermostat is 195*.