power loss even with lots of newer stuff...

so even though i have 4.88s and and a ton of new sensors over the past year i still dont have tons of balls and i dont get it, some of the guys on stock gears seem to have more power on the same 33's?!
here are my guess's:
1.clogged cat (doesnt rattle though)
2. could my tcu not let my tranny rev high enough? in 1-2 (aw4) when its in the power band its fine....seems like its shifts too early most of the time, why is that??? seems it used to have more power in 3 with 3.55s than in 3 with 4.88s
3. something with the egr maybe? i think solenoid isnt sending out vaccum through last time i tested it...
4. something else?
5. could a bad alignment cause too much drag??

new stuff within the past year to year and a half:

02 sensor
distributor and cms
plugs
(used) bigger plug wires
exhaust manifold and gasket(old one was crakced)
coolant temp sensor
vacuum harness and all vacuum lines...
tps
cps
alternator
battery
super huge ground and hot wires for the battery and alternator( 0 or 2 guage)
new IAC
new muffler
i plugged off the old disco axle, i capped the vacuum lines and zip tied the caps as well..., could i maybe have a vacuum leak through there?
ps pump
19# ford injectors
4.88s
oil changes
drained tranny and refilled(not a full flush, but seemed to help a tad bit)
cleaned the hell out of the MAT sensor
rustys air tube


all of these things seem to help temporarily, and when the jeep isnt so loaded at sea level its faster for sure, but there seems to be something holding it back...


3 years old:
radiator , hoses, water pump....

ran mopar CCC through the combustion chamber a few times...
could i have messed up the 02 sensor?

also, at higher rpms it has balls, its just that it seems to want to downshift from 2 to 3rd way early, like at 2300 rpms? the tps is adjusted correctly.
could this be a tranny cable too loose thing too?

If the "trans" fuse is blown in the fusebox, your AW4 trans will be stuck in "comfort" mode and exhibit the symptoms you are describing. If the fuse is blown, I would suspect a shorted trans mode switch. I've had 2 of them do this to me. Easy fix. Remove the switch and jumper two wires , the one that's tan and the one with the stripe. The black is ground. Leave it alone.

Are your brakes dragging? I've been having that problem on my 88. The front brakes will drag and I have a pretty noticeable power loss. Also, is your tps adjusted correctly? Mine isn't right now and it bogs down/doesnt shift like it should.

js_customs said:

Are your brakes dragging? I've been having that problem on my 88. The front brakes will drag and I have a pretty noticeable power loss. Also, is your tps adjusted correctly? Mine isn't right now and it bogs down/doesnt shift like it should.

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can you even adjust your tps? i was planning on buying a new one cause my xj gets stuck in od after 45 mph and when i first drive away it bogs down for a few seconds then gets back to normal

latenights said:

can you even adjust your tps? i was planning on buying a new one cause my xj gets stuck in od after 45 mph and when i first drive away it bogs down for a few seconds then gets back to normal

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I've heard of it on the Renix models but not sure about HO models.

Run a compression check. The 4.0 builds up alot of deposits on the valves over time and you may have leaky valve seats. I resurfaced my head and lapped the valves to remove the deposits and it made a noticable difference in power. Also run Marvel Mystery oil in your gas to prevent any further deposits.

cruiser54 said:

If the "trans" fuse is blown in the fusebox, your AW4 trans will be stuck in "comfort" mode and exhibit the symptoms you are describing. If the fuse is blown, I would suspect a shorted trans mode switch. I've had 2 of them do this to me. Easy fix. Remove the switch and jumper two wires , the one that's tan and the one with the stripe. The black is ground. Leave it alone.

Click to expand...

when you say the trans mode switch you mean the one in the dash for comfort and power? and if it shorted then i should bypass it and just wire into constant "power" mode? that sounds great to me! and then connect the tan and striped wires and it will keep it in power mode? that would make sense that it is stuck in comfort mode
ill check that out tonight...

and i do run MMO. my engine runs very quiet and smooth and idles and no stumble, its also very ballsy in the powerband, its that often it wont stay in the power band, unless we are wheeling, then in 1-2 it has tons of power....it will down shift too early, like from second to third it will shift at around 2300 rpms! i would think maybe 2600-3000 would be more appropriate...especially when going uphill fully loaded into the mountains....

could the 4.88s be doing anything negative? that is, since i didnt change the speedo gear could anything be reading off? or anything else like that?

how do i know if i have brake drag? would it be a caliper slowly going out then?
should i just bleed the system one more time and see what happens? also put the tires in the air and spin em maybe?

If you installed 4:88's and didn't change the speedo gear then you are definitely getting wrong speed readings. To check for brake drag, jack it up and turn the wheels by hand. They should turn with no drag or noise from the brakes. Also check your front brake pads for uneven wear. When the caliper sliders get gummed up the caliper gets cocked and the pads wear crooked. Another cause of brake drag is when the pads wear into the slides on the knuckles. I have had to weld up the grooves in my knuckles and grind them back flat before. When this happens the pads can drag on the rotors.

yah i know my speedo is off , its roughly 15mpg over for speeds under 70mph, so when it says 70 im going 55... when its says 80 im going 66 ish. i was thinking if maybe there was something that read the speed from the speedo and used that to calculate shift points or is it purely a mechanical guage that only goes from the case to the gauge.
ill check for brake drag and check the tranny fuse, maybe try to find the tcu and check its grounds, spray some more mopar CCC thru the intake and let it sit and clean out...maybe spray some through the spark plug holes to clean up any more deposits???

I didn't happen to notice where you said you adjusted the throttle body pressure cable for the AW4.

i didnt adjust that cable yet! joe peters i was just thinking that too....do i just pull it out further???
i plan to maybe hit that up tonight!

And yes, you understood my description of the power/comfort switch and fuse correctly.

blondejoncherokee said:

i didnt adjust that cable yet! joe peters i was just thinking that too....do i just pull it out further???
i plan to maybe hit that up tonight!

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Here is a good thread on the adjustment: http://naxja.org/forum/showthread.php?t=1015963

thanks ! bookmarked and read!
im gonna jump on it now!

im very interested in the guy that posted about adjusting the renix tps to 10%. does he mean 10% higher voltage or 10% lower voltage? im assuming he means voltage , as in, the voltage to calibrate the tps...

blondejoncherokee said:

im very interested in the guy that posted about adjusting the renix tps to 10%. does he mean 10% higher voltage or 10% lower voltage? im assuming he means voltage , as in, the voltage to calibrate the tps...

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On the adjustable Renix TPS reference voltage is 5.0 and the TPS should be set for 0.8 on the manual transmission. So, if your reference voltage measures, say 4.85, you would want the TPS voltage to be the same relationship: 0.8 / 5.0 = 16 %, so for 4.85 you would want TPS voltage at 7.76, or 16 % of the reference voltage.

I'd start by checking pulleys on the serpentine belt and look for any that have a lot of drag

i adjusted the tranny linkage cable and it seemed to help alot, also, the tranny setting was on comfort for some reason so i put it back on power. that seemed to do alot.
on the tps on my auto it is supposed to be 0.8 at closed throttle right and 4.8-5 at WOT? right?