robguitargod1

I've searched, but still can't really find a clear answer. So I did the 703 injector swap, and am not getting TERRIBLE fuel mileage! After a little searching I noticed I'd never reset the computer. So I held the battery cables together, but I still fell like my MPG is pretty bad.

Question is, can an O2 sensor go bad without triggering your check engine light? Also, is it possible to throw a code but not indicate it by triggering your check engine light? What I mean is, I suspect my O2 sensor is bad but my check engine light isn't on. What are the chances that an OBD scan will see a code?

Txssp

Well it is usually recommended that You replace your O2 sensors every 60-70k miles. It is possible that your sensor is on it's way out but still working just enough to not trigger a CEL. You might want to look into starting to replace sensors if they have never been replaced such as the Air charge sensor, Idle air control, Throttle position sensor, and maybe the map sensor. All these get carbon build up on them and degrade they're performance over time. But in the end it's still just a jeep your never going to see high 600 miles to a tank LOL.

djb383

Is the CEL bulb test working?

robguitargod1

bulb test? You mean watching it flash when you start the car?

VTJeep

i recently threw a liteny of parts at my jeep to get it to stop this weird hesitation thing. and each time i replaced something, there was a small imrovment, but nothing that seroiusly made a difference. the only thing left is my o2 sensors, both front and rear. they are pretty cheap and easy. however the trick was just how much moneys did i wanna blindly throw at it? i started as basic as blowing out gas lined and then progressed to plugs/wires, cap/rotor, TPS, IAC valve, and then pulling off the TB, dissasembling it and hitting it with carb cleaner. after this the problem was pretty much gone. the only things i didnt do was to replace the coil, and o2 sensors. andi might still, as all of these parts do add up to the overall preformance.
long story short: simple and cheap first!!! imho

robguitargod1

Cheap O2 sensor?

djb383

Yes, it's on a couple of seconds at start-up then goes out. I was thinking maybe CEL bulb burned out thus falsly showing no CEL when there actually was one.

VTJeep

yes.

robguitargod1

What do you consider cheap? I found one for $54.

VTJeep

rockauto parts.com

Gee oh Dee

Someone here who has a writeup of the swap suggested that you must turn your headlights on in a certain way to truely "reset" the ECU.

I don't know if its true, or if it really works, but its worth a try as there is no cost in doing so.

Try searching, I know you'll find the thread.

Nevermind, found it for you...looks like you've seen the thread already. Even posted in it.

Did you ever try this????

https://www.cherokeeforum.com/f2/703-784-injector-swap-write-up-66456/

robguitargod1

Well I did some headlight stuff. From what I read i held the bat cables together for 30 seconds, turned key on, turn headlights on for 30 seconds, turn headlights on, turn key off, then start vehicle.

VTJeep

i think it goes...
>bat terms together for 30 sec.
>turn ignition to ON pos.
>turn headlights on/off
>turn ign. off
>50 starts to reset...
at least i think... there might be a step im forgetting... or adding... idk...

Gee oh Dee

I posted the link and the instructions from it.

robguitargod1

Thanks. I posted in the thread too.