01 4.0 powertrain in an 06

[06melanore]

New here so be easy on me lol. So my jeep has just over 100k always lacks power in 2wd or 4wd going uphill especially offroad. Have fought this for awhile. No engine light no codes. Wrangler fix pcm done no cats to have clogged. 4lo it will pull. Also 538 gears 36in tires. Not sure what else to check here. So now I'm at the point of taking the entire powertrain and wiring from an 01 doner and swapping everything over. I've pulled the last of my hair out. Any help on power issue or problems with swap would be appreciated. Tia glad to be here

 

[lBasket]

New here so be easy on me lol. So my jeep has just over 100k always lacks power in 2wd or 4wd going uphill especially offroad. Have fought this for awhile. No engine light no codes. Wrangler fix pcm done no cats to have clogged. 4lo it will pull. Also 538 gears 36in tires. Not sure what else to check here. So now I'm at the point of taking the entire powertrain and wiring from an 01 doner and swapping everything over. I've pulled the last of my hair out. Any help on power issue or problems with swap would be appreciated. Tia glad to be here

Do you currently have a 4banger or is something wrong with your current 4.0?

 

[06melanore]

Do you currently have a 4banger or is something wrong with your current 4.0?

4.0 now just can't figure out lack of power issue. Daughter,son,buddy all run 4.0s with higher miles and all are WAY more powerful in 2wd or 4wd hi. Only reason 4lo is better is due to 4:1 t case going to replace fuel pump this weekend. Had an issue with it last ride

 

[B1Toad]

Also 538 gears 36in tires.

Have you tried temporarily borrowing a set of smaller tires to see how it does?

 

[06melanore]

Have you tried temporarily borrowing a set of smaller tires to see how it does?

No need mine measure 35 and the others I ride with are same or bigger

 

[JKP]

Check the compression to see if the rings are shot.

Unless it was abused, it shouldn't even be close to worn out at 100K. Got 280K on mine.

You would need the OPDA with cam sensor, the flexplate, crank sensor from the 06 at a min on the 01 motor to work with the 06 PCM.

 

[JustDandee]

4.0 now just can't figure out lack of power issue. Daughter,son,buddy all run 4.0s with higher miles and all are WAY more powerful in 2wd or 4wd hi. Only reason 4lo is better is due to 4:1 t case going to replace fuel pump this weekend. Had an issue with it last ride

Seems like you have some comparables- large tire rigs too? I am thinking I would look at doing a compression check on the engine. But also have heard a 9” consumes some power compared to stock.

 

[06melanore]

Check the compression to see if the rings are shot.

Unless it was abused, it shouldn't even be close to worn out at 100K. Got 280K on mine.

You would need the OPDA with cam sensor, the flexplate, crank sensor from the 06 at a min on the 01 motor to work with the 06 PCM.

Have a complete donor pcm wiring etc

 

[06melanore]

Seems like you have some comparables- large tire rigs too? I am thinking I would look at doing a compression check on the engine. But also have heard a 9” consumes some power compared to stock.

Was like that before I swapped to the 9in

 

[macleanflood]

Emissions laws? State inspections?

Plugged cat?

I love my 97. After 98 they all got too complicated for my tastes.

Checked for a cracked head on the 01 donor?

-Mac

 

[06melanore]

Emissions laws? State inspections?

Plugged cat?

I love my 97. After 98 they all got too complicated for my tastes.

Checked for a cracked head on the

Emissions laws? State inspections?

Plugged cat?

I love my 97. After 98 they all got too complicated for my tastes.

Checked for a cracked head on the 01 donor?

-Mac

No emissions and head seems good

 

[JKP]

Remove the oil cap and look down. If you see TUPY, the head has been replaced with the good one. If not, you have a head prone to cracking. They crack and leak directly under the oil cap.

 

[macleanflood]

No emissions and head seems good

Excellent.

This sounds like a pot/fire situation.

If you've got lots of time and patience go for it with the understanding that the "new" engine is worse or the same... necessitating swapping back in the original guys and perhaps rebuilding your original engine.

You might want to consider stroking your engine to a 4.7 or putting @Jezza turbo kit on it.

-Mac

 

[lBasket]

There isn't really an enormous number of things that would make it super underpowered and not throw a code. It kinda sounds like you need to figure out if anything is different/wrong your engine or if you have different expectations than your friends?

If you have a bunch of similar rigs that you think run better maybe you can compare LT/ST fuel trims to see if there is any noticeable difference. Can you check timing advance on these maybe check out stuff like that and see if yours is doing anything weird.

 

[06melanore]

There isn't really an enormous number of things that would make it super underpowered and not throw a code. It kinda sounds like you need to figure out if anything is different/wrong your engine or if you have different expectations than your friends?

If you have a bunch of similar rigs that you think run better maybe you can compare LT/ST fuel trims to see if there is any noticeable difference. Can you check timing advance on these maybe check out stuff like that and see if yours is doing anything weird.

Going to do compression ck and fuel pressure ck this weekend. Will post back results

 

[06melanore]

Ok so installed new bosch fuel pump, air filter, and spark plugs. Haven't drove yet working on new battery mount. got a plan for tomorrow to get it out under load in 2wd/4wd hi and see if anything has changed. Compression ck was within spec 140-160 all cylinders. Only concern is 1 spark plug 3rd from the right. Should the color of this point me in some other direction? Injector?

 

[JKP]

That would be about the only reason for it to look so different.

Actually all of the ones in my 06 look like it, not the others when I change them.

Have you changed the O2s?

 

[06melanore]

That would be about the only reason for it to look so different.

Actually all of the ones in my 06 look like it, not the others when I change them.

Have you changed the O2s?

No cats on mine

 

[JKP]

O2s have nothing to do with cats. If you eliminated the O2s, problem found as they control the mixture.

 

[06melanore]

O2s have nothing to do with cats. If you eliminated the O2s, problem found as they control the mixture.

Correct. No I haven't changed them. Wouldn't they throw a ck eng light ?