losing power

[xdark1000]

I didn't notice that detail about the wheels not moving at 3000 rpm. He said that was in 4 lo too . i second that . tranny or torque converter.

 

[blondejoncherokee]

I am having a similar problem and I think it may be tranny related. On the last rubicon run I lost all forward movement, had to have been the tranny.

 

[rockclimber]

A Transmission rebuild doesn't sound like any fun.

 

[old_man]

I always start from the beginning with the old school ways. I do a plug reading, do a compression test, and get a good vacuum reading at idle and at higher RPMs.

Those three things will allow you to diagnose almost any issue.

Plugs can show you if you are running too rich or lean, as well as coolant leak into the cylinders or shot oil rings.

Compression will tell you a lot about the state of the compression rings and/or your valves. If the numbers are low, do a wet/dry compression test on all cylinders.

Vacuum can show you burnt/sticky valves, clogged exhaust, and vacuum leaks.

You said you have an exhaust leak. That can really screw with your O2 readings and cause the computer to not adjust the fuel mixture correctly. A plug reading will show that up as well.

A bad MAP sensor can throw off you mixture as well.

How is your mileage? A temp sensor that is off can screw with the computer as well, leading to lean/rich conditions.

I would do a fuel pressure test.

You can also have a bad tranny, slipping or failed torque converter. On the highway, does the torque converter lock up as it is supposed to?

 

[rockclimber]

I always start from the beginning with the old school ways. I do a plug reading, do a compression test, and get a good vacuum reading at idle and at higher RPMs.

Those three things will allow you to diagnose almost any issue.

Plugs can show you if you are running too rich or lean, as well as coolant leak into the cylinders or shot oil rings.

Compression will tell you a lot about the state of the compression rings and/or your valves. If the numbers are low, do a wet/dry compression test on all cylinders.

Vacuum can show you burnt/sticky valves, clogged exhaust, and vacuum leaks.

You said you have an exhaust leak. That can really screw with your O2 readings and cause the computer to not adjust the fuel mixture correctly. A plug reading will show that up as well.

A bad MAP sensor can throw off you mixture as well.

How is your mileage? A temp sensor that is off can screw with the computer as well, leading to lean/rich conditions.

I would do a fuel pressure test.

I'll look into all of this.

fuel pump is going to get swapped anyway. 210k on the original. the check valve is toast so you have to prime the lines every time you start it or it will crank forever.

You can also have a bad tranny, slipping or failed torque converter. On the highway, does the torque converter lock up as it is supposed to?

seems to.

 

[xcm]

From the video, it looks like youve lost drive, nevermind power... Im no aw4 expert... but id be checking trans fluid color/smell.

 

[rockclimber]

From the video, it looks like youve lost drive, nevermind power... Im no aw4 expert... but id be checking trans fluid color/smell.

It's never smelled bad and/or looked burnt.

This is the 3rd or 4th time this has happened on a trail.

Last time was in little sluice on the rubicon.

 

[srmitchell]

What does the fluid look like?

No way your trans is okay if you are able to rev to 3000 in 4low with no movement!

 

[rockclimber]

fluid looks fine. I'll snap a pic of the dipstick next time I'm near the jeep.

honestly it wouldn't surprise me if it was the trans, but its never exhibited any slipping in any other circumstance. and I really don't want to admit its that because then I have to deal with it :laugh:

even with the less than ideal gearing of 4.56 and 35"s it still has great engine braking.

it honestly feels like the engine isn't making power under those circumstances. but the compression is good.

I've got a new fuel pump, a replacement header and new O2 sensors. I'll start there.

 

[souske]

fuel pressure/volume would be the first place to start