Okay guys, I just moved to Laramie, Wyoming for Wyotech. My Jeep is sluggish as all hell!! I used to be able to put the metal to the wood at 30 and set 4 grown men in their seats, and it won't do anywhere near that now.

My instructors said to take the battery cables off, and touch them together for about 2 minutes, then re attach. Flashing the computer, and losing all stored info.

Is there a certain way to do these 4.0's?? Or is the cable thing correct?

1997 Sport, 4.0, automatic, 4x4.

 

Their correct.. what that will do is have the computer "relearn".

I have also read mention of a high altitude TPS.. i'm sure some of the others here will chime in on that.

 

battery cables will cause the re-learn.this is correct, and if your performance is still off you can have it flash for the higher altitude

 

Okay, is the flashing done with a scan tool?

 

You need to touch them for a bit, then put in the key, turn it to on, but dont turn it enough to start it, then turn on the lights, then turn them off, then turn the key to off...

Thats what I read to reset the computer

 

would altitude make that much of a diff? cuz i bought mine in ft collins @ 5500 ft. and i live in estes @ 7700 ft. its sluggish but i just thought that cuz its got 250,000 on it??

 

Resetting the computer isn't going to fix this problem, altitude is just that altitude...the higher it is the less oxygen in the air and that is what is causing you to lose performance. Good luck having the Jeep relearn how to make the same power with less air...just sayin'

 

I drove my 2000 XJ with 31s out to Wyoming when I got a job in Casper. It sucked driving anywhere besides driving threw town. Interstate speed: right to the floor and watch the gas gauge go south. So after a couple weeks I bit the bullet and bought a 2001 Cummins. Diesels are not effected by altitude. Let er rip.

 

The turbo on that Cummins is what is really helping out in the altitude more than anything.

 

Well I moved from central Illinois, to 7200ft. There was a big *** difference. But I did the touching, turning lights on off, yadda yadda, and I HAVE gained performance back. I HAVE. Not all of it, but I can def tell!

 

Diesels are just as affected by altitude but you've got way, way more power to begin with.

You drive torque and race horsepower...and diesels make torque - especially that inline 6 Cummins. Something about the way inline motors deliver torque seems more better than V configuration motors. That's not a "fact", just a seat-of-the-pants thing. I've had all three...Cummins, PS, and Duramax...and liked the Cummins best.

 

The MAP Sensor is constantly reading the ambient barometric pressure while the motor is running and reacts to the absolute pressure in the manifold. This info is used by the PCM to varies the Air-Fuel Mixture. The greater the altitude, the lower the air density, the less fuel used.

The relearn procecure does nothing to modify the basic parameters of the PCM and therefore has no effect on increasing the Torque or Horsepower from the stock output levels.

 

just to approach this correctly, is the relearning procedure as follows?

1) attach battery cables together
2) turn key to on
3) turn on headlight switch
4) turn off headlight switch
5) take key out of ignition
6) disattach cables and reconnect to battery as usual

or do I have it wrong?

 

I've never heard of having to do all that. Simply touching the cables together for about 10 seconds has always worked for me

 

Touching the pos and neg cables together only clears error codes.