Bad gas mileage just got worse

It should be under the dash. Not sure which side. Im betting its near the driver side pedals since that makes the least amount of sense.
 
It should be under the dash. Not sure which side. Im betting its near the driver side pedals since that makes the least amount of sense.

LOL, that is right, just above the gas peddle on Renix.

How has the debugging turned out?
 
I didnt get a chance to work on it today due to some issues with the youngest kid. I did score on craigslist today and bought a whole new wiring harness from a guy parting out a 1998 XJ limited for 35 bucks. It should be here tomorrow so I'll drop that one in and start tearing apart my old one and re wiring at work (because its that boring) just incase. Never know when you'll need it hahaha. Hopefully it fixes my problems. Hopefully we'll have good results tomorrow but who knows.
 
You can change how much fuel the engine is getting in closed loop, several ways.... MAP sensor adjuster and also ACT( Air Charge Temp) sensor adjuster........ Speed Density fuel injection works the same on Renix as it does on Chrysler SBEC or SMEC...... Here is my tail pipe emissions readings using the MAP adjuster only, I also own a DRB 2 and can watch the injector pulse width decline as I turn the knob on the MAP adjuster to simulate more engine vacuum, and all this is going on in closed loop....... Dont expect the MAP sensor adjuster to give you 40 mpg, but it will give you at least 3 to 5 mpg better then you are getting on a well tuned engine with a few miles on it.....

Here is my readings closed loop at idle and at loaded reading 39 mph on rollers.....Gutted cat, no muffler and just a tail pipe........All achieved with just a simple MAP sensor adjuster........

jeep%20emissions%202013.JPG



That will only change fuel consumption in open loop. Most of the time its in closed loop, getting feedback from the O2 sensors.

Unless the engine is modified leave the MAP sensor alone.
 
Ok folks here's an update:

Got the new to me harness in today off a 98 limited XJ w/ about 70k miles on the engine. How much you ask? 35 bucks plus shipping. Excellent deal. So I cleaned up all the connections and hooked it up. Not as easy as it sounds but it got done. Started it up and it was still running like complete crap. After smacking my head off the hood a few times I decided to let it warm up and put my tools away. Something dawned on me... I forgot to plug the number 6 spark plug back in. Yeah I'm retarded. Anyway I reset the computer and started it up again. MUUUUUUCH better. Took it around the block and my tires came loose when I hit the gas. I was pretty stoked. No more codes either.

In conclusion - Running at 730-770 RPMs, throttle response is much better, motor is still shaking a bit but not nearly as bad and lastly my gas mileage driving around base which used to go from 4mpg to 11mpg depending on how much stop and go I was doing went to 8mpg to 21mpg. Keep in mind the 8mpg is coming off a stop sign. Not too shabby. It should only get better from here also since the computer still has to adjust. I'll update with my highway MPG once I get a chance to get off base since I forgot my wallet when I left this trip.
 
I chased a bad idle on a V-6 Ford Taurus for weeks, that turned out to be a hard to reach, impossible to see spark plug wire that had come loose, and OBD-II never set a code!!!

Glad you got it figured out! Jeep gremlins tend to travel in a pack, like a wolf pack, LOL.

Now try those other CPS sensors, non dealer, and see if they were really bad off the shelf, or not, when you get bored someday.
 
Back
Top