swamper

i have a 90 xj and it has a switch for the tranny that you can toggle between comfort and power. i get the idea behind the switch, but i've turned it on and off, and haven't noticed any visible change while driving. which setting should i use for everyday driving? or wheeling?

finneys98xj

leave it on power 24/7 for better gas.

OverlandZJ

Power is for towing etc, the motor tachs up higher before trans upshifting. The comfort shifts at a lower RPM therefore conserving fuel economy.

offroadnut36

overland is right.

mycherokee1989

My little light doesn't turn on when I change modes (getting a new light bulb for it), but does the engine make any noticable change? does it idle higher or anything? Would I be able to tell if it wasn't working properly?

JeepCoMJ

no.


nope. overland is WRONG.

the only thing that the comfort mod does is allow for shifting at lower RPM's. this keeps you comfortable so you don't get a hard shift. by doing this, the transmission shifts short of the ideal powerband ratio, thus making the motor to use more gas to get to speed.

however, the Power option allows for shifting at a higher RPM. by shifting at a higher RPM, the transmission shifts in the engine's ideal powerband...giving it it's best fuel economy. this isn't quite as comfortable of a shifting method, but it isn't THAT much of a difference.


for economy, keep it in power. anyone who tells you otherwise is wrong. end of story.

mycherokee1989

so jeepcomj u seem like you know a lot about it, which one should be used for wheeling? power?

ulendo

sounds more like it depends on how the specific XJ is set up, and how you drive: the high output setups like rpms more than the Renix motors, for example, although AFAIK, only renix setups came with the power switch

Mine, with numbers: '89 Cherokee Laredo, 4.0, 350,000km, 3.54's, 31x10.5's, free air intake, 2.25" exhaust, no A/C, Safari Rack on w/ spare on top....

17-18 l / 100km city in power mode

13-14 l / 100km city in comfort mode.

Best ever was 10.0 L / 100 km hwy in comfort mode... taking it dead easy @ 50 mph on empty, icy roads.

Comfort mode upshifts earlier, locks the convertor earlier,resists downshifts, uses torque to drive it not rpms. IMHO, the biggest problem with power mode is that you tend to USE it, and here, at least, it downshifts all the time, wasting fuel. Alternately, in comfort mode, it doesnt feel so frantic, and loafing feels right...

JeepCoMJ

H.O.'s are permanently wired in the power mode.

power doesn't really give you much more, but as you've noted, it's a SIGNIFICANT economy gain in the power setting.


use power all the time. if you want to use the switch space, get in there and make a small jumper wire, and hardwire it all the time through that connector. use the switch for something else.

OverlandZJ

Copied from a post on NAXJA where he quotes the owners manual.

According to my owner's manual for my '88 Laredo, the blurb states:

AutomaticTransmission Mode Selection Switch
Automatic transmission mode selection allows you to select different transmission shift characteristics to suit your driving style and road conditions. The switch has two positions:
Power: In this mode the transmission will be more responsive. It will upshift at higher speeds under hard acceleration and downshift more quickly. An amber indicator light on the switch will glow in this position.
Comfort: This mode is for normal driving. The transmission will upshift at lower speeds for more economical operation.


Thats the way the manufacturer designed the system to work. Now, with all the discussion over the years on this i'v formed my own opinion through reading and 1st hand experience. I shared my experience, which cant be dismissed as a blanket statement of being wrong. Obviously some may have opposing experience... i have my own theory on that as well.

Some also say the trans will wear the clutch discs faster in comfort, this may be true but i personally have well over 200K on an AW-4 that always ran in comfort till about 35K ago. Theres also quite a few running well over 300K that claim to always use comfort mode as well.

Jeepco, you have your opinion and thats fine.. i can accept that.

JeepCoMJ

it's not an opinion when statistics regularly show that better mileage is obtained by the use of the POWER selection.

here's something to think about, a way to relate. When has luxury/comfort EVER been less expensive than moderate power?

the mathematics of what the factory INTENDED do not work. just like the vacuum disconnect, the power/comfort switch is an epic FAIL. in 1991, in the U.S. at least, chrysler removed the power/comfort switch and put a constant accessory power to the power/comfort pin in their transmission computers. They did this because their theory was proven WRONG.

therefore, no matter how well intended you are by referring to an obsolete owners manual, the fact of the matter is that time tells the truth, and gives the answers. the answer is to use power for economy, NOT comfort.

mycherokee1989

I'm glad we had this discussion

OverlandZJ

Show me these statistics you mention.

I dont mean to be argumentive but my 1st hand experience doesnt agree with your opinion. If you can provide convince me that my memory is skewed i may reconsider reinstalling my power/comfort switch.

JeepCoMJ

ha. re-installing? did you bypass it? or decide to just leave it be?

mine is NOT an opinion. it is my experience based on 3 jeeps. one 1987 comanche 4.0 auto, 4.10 gears 33" tires putting it to stock ratio, with the speedometer tuned PERFECTLY. I got 14 to 15mpg city in comfort, 17 to 19mpg in power. highway I got 17mpg comfort, 21-22mpg power.

1988 cherokee pioneer 4.0 auto 2dr 225's 3.55 gears, I got 15mpg solid city in comfort, 17-18mpg city power. highway 17-18mpg comfort, solid 22mpg power.

1988 comanche 4.0 auto 3.75's 31" tires proper speedo gear, I got 12 to 14mpg city comfort, 16mpg city power. 15mpg highway comfort, 18mpg highway power.
This truck no longer belongs to me. I sold it to my friend zach and he is regularly getting worse mpg, but he drives it hard.

I take mpg readings when i haven't beaten on the jeeps. these are tanks that I drive to gauge mpg.

power makes the engine work less to get to speed. if you are light on the pedal, and accelerate slowly, you will net the most gain by using power. I cannot stress this enough.

mike37

If you drive like grandma the comfort will give better millage
but for most drivers the power will be more efficient
its all in how you drive

for me its power all the way