Wife's led foot or something causing poor milage-95 Cherokee

ronpapworth · #1 (**permalink**) 10-07-2003, 07:42 AM

Tested the milage a couple times. She is getting right around 11 MPG. Sprayed out the throttle body that was pretty gunked up, but can't really see into the air regulator port on the side of the TB. I am assuming the is some sort of wire in there that may need to be cleaned better? Pulled the O2 sensor and it didn't look out of the ordinary. I was going to bench test it, but have never bench tested a 4 wire sensor. And it appears the code puller plug is an OBD 1 as I have a square plug on the right side of the drivers feet. Here are my questions:
1. Should I pull the Air regulator off the TB(star head bolts) and spray it out better?
2. Does anyone know which of the wires I touch the multimeter to on the 4 wire o2 sensor to get a reading when I hit it with a blow torch on the bench?(2 black, a grey and a white)
3. Am I looking at the right plug for the engine codes? I was told a triangular plug is OBD2 on the 95 and the square one is OBD1.
4. Is anyone in the Cincinnati area with an OBD 1 scanner that could hook me up? Because I never take my cars to the dealer and would love for some one to pull the codes on this thing for less than 80.00.

Thanks all.

Bounty__Hunter · #2 (**permalink**) 10-07-2003, 08:23 AM

Your Jeep is OBD1. I don't think you'll be able to pull any codes unless the check engine light is on. If it's on, you may be able to pull them yourself using a specific key cycle.

I'd suggest replacing the o2 sensor if you never have, it's $40 and is probably due in a Jeep that age.

The throttle body is simple to remove for a better cleaning, it's just 4 bolts, couple wiring connections, and throttle linkage. Then you can remove the IAC motor and housing (4 tamper proof torx bolts) and give everything a good cleaning.

Don't forget a good tune-up, I'm sure you've already covered that base. I've found that the best mileage is achieved by improving your driving habits, slower acceleration from a dead stop and slowing the top speed down to the speed limit. You'd be surprised how much gas you save driving 10mph less.

ronpapworth · #3 (**permalink**) 10-07-2003, 10:08 AM

Interesting. So there will be no codes if the check engine light isn't coming on... makes sense!

yes, you are correct, I went through it when I got the Jeep last November and did plugs, cap, rotor, wires and all the fluids, and of course air filter.

Is there a gasket I need to get before I pull that TB off?

I'll make sure I have a torx bit the right size as well. No delicate parts to work about in the air thingy?

Trust me on the driving habit thing, she's like a mule. stubborn. I would govern the thing if I didn't think she would pull out in front of a Semi one day and need the juice...

MudderChuck · #4 (**permalink**) 10-07-2003, 03:39 PM

I get about 25% better mileage, if I keep it under 2000 RPM or so. Save the pedal for special occasions.

XJNick · #5 (**permalink**) 10-07-2003, 08:16 PM

Quote:

So there will be no codes if the check engine light isn't coming on

Not always true. Sometimes you can only retrieve the codes that light the Check engline lamp through a key on-off cycle. There are codes that will NOT light the check engine lamp. It is likely that you can only retrieve these through a scanner. An OBD-II style plug is a sort of a D-shell shaped connector and has 2 rows of 8 pins totaling up to 16 pins max. (you may have less than 16).

Late '95 - early '96 was when OBD-II began being implemented, so some vehicles were OBD-I and some were OBD-II that were made during that time.

-Nick

graewulf · #6 (**permalink**) 10-08-2003, 06:01 AM

out of curiosity, running bigger than stock tires? this will affect your mileage.. i just went from 225/75/15 to 30x9.5x15... lost about 2MPG

Benskate1 · #7 (**permalink**) 10-11-2003, 12:38 PM

bad milage, run some of that 99 cent fuel injector cleaner, its just strongly alocholated gas it works a little. PCV valves, clean em or put new ones in, yes replace the o2 sensor, clean ye olde air filter, is your exaust full of crap? you might need a new catalatic converter or muffler.

with that fuel injector cleaner stuff the way to make it work good is not to follow the directions, wait till its almost out of gas and then pur the bottle of that stuff in, then run it at high rpms and it will run all the crap out of fuel system.

sparkyshotrods25 · #8 (**permalink**) 10-21-2003, 03:55 PM

turn the ignition from the off possition to the oon position 5 full times without starting it,let it sit in the on possition and watch the check engine light.When it starts blinking one after another count how many and write the # down.it will stop for a second or two and start again(this is the second number for the code) when it stops blinking for around five seconds this is a new number too the next code.Haynes manuals better explain it,but thats how you pull codes from a crysler ,i think it more than likey is timing ,tune up,o2 sensor ,and type or gas.sometimes it is the driver.lolbest of luck