please help. no idea

[BUKI]

okay, figure this one out!!!

So, im on the quest to figure out why my mileage  has been so horrible, approx.  8-10 mpg.  The jeep is a 2.5 wth 33s and has been  running very rich lately.  black smoke, and the smell at startup, it smells as though you could light the tailpipe and have flame throwers.  I have now changed ALL sensors with new ones, except for AIT.  I just ordered one up.
until it gets here i thought i would try something I stumbled upon. A webpage said you could remove the ait and jumper the lead with a resistor. 4700 ohm.  to trick the ecu into thinking it was very cold or something.  anyways I went to the source and picked up a set of resistors for 5$. and put it in.  the jeep not only runs, but waaaaaaay more power.  probably 20-30 horse at wot between 2600 and 3800.

Now relax, i am not saying that this is what everybody should do.  More than likely the IAT is just way far gone. and replacing it (whenever it gets here) will do the same thing.  the weird part is,  cold starts still really rich and mileage still same.

any ideaz.  I have changed everything, cap, rotor, wires, plugs (3 sets of different kinds), coil, tps,idle motor thingy, coolant temp, now IAT, map, 02.
hundreds of dollars later still no difference. 
I have another computer, my wife is picking it up from her sisters house tonight.  Ill throw that in tomorrow.
what am i missing??? :'( :'(

[2grand4u]

this way sound dumb but what is a AIT 

[BUKI]

air intake temp sesor, or IAT intake air temp sensor, or MAT manifold air temp, or IAC intake air charge... etc, etc

[2grand4u]

thxx

[barmanjay]

Maybe your injectors are due for replacement?

Doesn't IAC solenoid mean intake air control solenoid

[BlackYJ]

What about the cat and o2 sensor?  When the cat goes you lose tons of power and it smells

[barmanjay]

Well,.. sounds like its no good and better get rid of it to me for $100

[BUKI]

it was nice to meet you barmanjay, and again no you can not have my jeep

the 02 was changed last week and there is no cat, never had one when I got it.  but this problem has only just begun about early spring, been chasing it ever since.  oh, I forgot fuel filter and pump changed, as well as pressure regulator diaphragm thingy.
she has great power, and no drive-ability issues, thats why its so weird.  approx 100-150 kms per tank 50 odd dollars.

[hps4evr]

you said you were chasing the problem since spring. what happened in the spring that could have caused a change. did you do any mods or perhaps do a repair that could have gone bad?

[BlackYJ]

she has great power, and no drive-ability issues, thats why its so weird.  approx 100-150 kms per tank 50 odd dollars.

The same thing actually happened to my Jeep.  I went from getting about 425 kms per tank to about 250-275 kms.  After two trips to the local Certigard, one to the Dealership, and $1200 later it was not really any better.  Now over the past couple years it has fixed itself and I am back to about 400 kms per tank.  They flush my coolant, flush the fuel lines, did an intake cleaning, etc, so I feel your frustration

[frenchy]

Change the thermostat in the spring?

Still have the TB spacer, 4.0l, bored out stuff on top?

[BUKI]

no, new/old throttle body from 4l.  But I did change the t-stat in late winter, you may have something.  ill chek it tomorrow.  Thanx frenchy

[cLAY]

No CAT? What year is it? Some years had an O2 sensor in the CAT. If someone cut out the CAT and didn't weld a bung back into the replacement tube to put the O2 sensor back in then the ECM won't be reading that sensor and will continuously run in rich mode.

Had some friends that did that, cut out the CAT and didn't put the O2 back in. They too complained about poor mileage and power. I talked them into taking it to a muffler shop and having the O2 sensor put back in. Mileage and power returned afterwards.

[mike s]

seems the 2.5 is poor in all fields. low power AND poor mileage. 250 km per tank is all i get. last i checked about 12mpg. no codes, everything new, tan coloured plugs and no soot in tail pipe. runs fine just lousy mileage and i'm only on 31's

[BUKI]

I changed the t stat yesterday it was a 180, can tire said it suposed to be a 195.  does this sound right?  i didnt think it was supposed to be that high.