Sucking gas and low power

G

Gasman1979

New Member
Joined
Jun 19, 2024
Messages
14
Location
Arkansas
Hello all. I’m new to the Wrangler world. I owned a tank of a Cherokee many years ago. Anywho on to my issue(s). My 1997 TJ 2.5L is idling pretty rough. I noticed today if it sits and idles for a few minutes it is extremely sluggish almost like it it loading up on fuel. A quick scan today showed long term fuel trims way off. It was at -22 but the short term was bouncing from 0 to -2.0. I ran to town and filled up. Town is about 16 miles away. Coming back I burned 1/4 tank of fuel ! I am running 31x10.5 tires so I don’t believe I am over taxing the 4 angry squirrels under the hood. I can barely maintain 65 mph as well. A few details before I release this to the interwebs for advice. There is no CAT. It has been cut off. My O2 readings are surprisingly normal at around .65 volts up and down stream to not have a converter. It does have a 4” rough country lift which is coming off this weekend. (I don’t care for the way it handles) the guy I got it from said he just did the timing chain about 3 weeks ago. I’m pretty good with later model engines but this thing is a dinosaur 😂. My Snap On Modis almost laughed when I plugged it up today. Speaking of, there are no codes. My fuel pressure is around 48 psi running and does droop a bit when the gas is revved. But only a pound or so. I know the fuel pump is showing signs of weakening but I think is in spec. Also to note right before I got it it had a tune up, plugs, wires, cap and button, coil. All looks new. I’m thinking possibly the guy couldn’t figure this out and now it’s my problem. Any thoughts or ideas before I start chunking parts at it ???
 
  • Like
Reactions: TurboTJ
Plugged cat probably...pull your O2 sensors to deliberately cause an exhaust leak and see if it runs better. You can also use a laser IR thermometer to look at temperatures.

-Mac
 
GregBelleville said:
Midway thru that wall of text he said the cat was cut out. 👍
Click to expand...

Yessir. Cat was removed and straight piped by a previous owner. That was going to be my first guess till I rolled unde
GregBelleville said:
Midway thru that wall of text he said the cat was cut out. 👍
Click to expand...

yessir. That was my first guess until I roll d under and seen it straight piped by a previous owner. I think imma replace the upstream O2 and see what happens.
 
My upstream O2 sensor gave me issues similar to this even without codes pertaining to it. It would idle rough at start up until it warmed up then it would run decent. Changed out the old one with a new NTK sensor and it was night and day with the idle at cold start up. This is the part number for the 2.5L upstream sensor.

IMG_8718.jpeg
 
Gasman1979 said:
I know sir. I’m trying to sort out WHY it is rich.
Click to expand...

I had a cracked exhaust manifold on my 97. Replaced it and my mileage went from 8 to 12.

Not all of my exhaust made it to the O2s so they told the PCM to richen the mixture.

If you want to see if you have exhaust leaks get a bottle of seafoam...start the engine, unplug the vacuum line to the brake booster...keep it running by revving the engine on the throttle body...dip the hose in the seafoam. It'll make a lot of smoke.

You can also get a smoke generator and plug that into your vacuum lines to check for vacuum leaks.

I'd say check exhaust first.

-Mac
 
Top Bottom
Back