kissthis66

When I got my 94 Cherokee SMOG'd the tech told me my rig didnt have an on board computer that would display error codes such as Check Engine light and what have you.

When I was searching the web today I ran across these JET performance chips: http://www.jeep4x4center.com/jeep-ch...mance-chip.htm

Can I use the one of these JET chips for my Cherokee? Its a 94 Sport 4x4 4.0L 5spd man

Thanks for helping a noob out! =)

Gee oh Dee

Chips are garbage.

Mycherokee96

Go to a different garage.....thats not an answer you should get out of someone who repairs auto's for a living. The modis I have at work has a DLC, (diagnostic link connector) for jeep......I use it all the time on my 94 YJ....4.0.......there's a 3 prong plug for it ...

rompnXJ

they told u ur 94 has no pcm and cannot store codes??

flip the key 3 times and be like well whats this haha.
and the pcm is in plain sight wtf is wrong with ppl.

VTJeep

Two things
First, wtf mechanic told you ya didn't have a computer???
Second, idk about chippin it.. Nominal gains unless the rest of your motor is tuned..

Edit- there are ways to free up existing ponies.. Do some searchin..

kissthis66

Its the first time I've ever been to a SMOG mechanic, so I just picked from the local phone book.

I know of the little things I could do to get more ponies out of the motor, its just this is my first rig that has a computer that would even allow a Performance Chip, so was just wondering if anyone else has tried them out and noticed any reasonable gain? Basically was the bang worth the buck?

Is the PCM that long looking black box on the right side of the motor compartment? If I remember correctly its next to the air filter??

@Mycherokee96 - where is the 3 prong plug located or where should I be looking, inside or outside?

Sorry for the noob questions, but this PCM is all new stuff to me.

Thanks for the help on this everyone!

VTJeep

Ya know I cant speak from experience with the chip.. It's not to say it wont give you any gains, cause it will. Things like a new filter will give you an increase.. But as for bang for buck is concerned, I think it's gonna come up a bit shy.. Real ponies cost about 30/ea so idk, theres my 02 on that.

Edit- I think your correct with the PCM location. On GC's it's behind the glove box, I think, but xj's are under hood. There is a chance I'm wrong!!!

montanaman

What that doofus mechanic was trying to tell you is that the computer in your car doesn't hook up to his OBD-II diagnostic tool. OBD stands for "On-Board Diagnostics."

Starting in 1996, almost all vehicles came out with OBD-II, which was standardized across the industry. Any OBD-II scanner can read codes off any OBD-II vehicle.

In your 1994 jeep, you have OBD-I, which requires a vehicle-specific scanner, or a different method (linked below). If something is wrong, your "Check Engine Light" (CEL) will come on. Then you get the code and it will tell you what the problem might be.

First, test your CEL. Does it come on when you turn your ignition on, then go off after the motor starts? If so, it is working.

Next, go here and learn how to get your diagnostic codes when your CEL lights up:
http://www.jeepforum.com/wiki/index....k_Engine_Codes

It's really very easy. You just need to turn your key on, off, on, off, on in a 5-second span. It will then cause your CEL to start blinking. Count the blinks for the proper code number. Read those few paragraphs linked above for a better explanation.

Hope this helps.

VTJeep

good info!

kissthis66

@montanaman - WOW SO SO HELPFUL!!!! Thank you so much!

kissthis66

so I just got home and ran the test to see what codes it would give me and according to the the link provided ( http://www.jeepforum.com/wiki/index....k_Engine_Codes ) it came back with the following:

12 Memory Standby power lost (Batt or computer recently disconnected)

15 No speed/distance sensor signal

21 Oxygen sensor signal out of range, possibly shorted

So:

12 - I haven't disconnected the computer or battery in months so any thoughts as to why its generating?

15 - I have a manual/gear driven speedometer, I know the gear is missing from the TC because the guy I bought it from told me he put in a NP231J and didn't have the gear for the speedometer to work. I've just been to lazy to run down to the junk yard and pull one. If and when I put that gear in the TC should this code stop generating? Or would it be something else?

21 - I passed SMOG a few months ago with flying colors so do I need a new O2 sensor?

Thanks again for the help everyone!

VTJeep

12: don't know for sure, but it could be an older code not cleared. Easiest/cheapest way to know is to have the codes cleared and see if anything pops up again. This is true for all of em, btw..

15: I imagine that installing said gear would solve this..

21: if you do indeed have a true code read that it's the o2, then it is very possible that one, or both of the sensors are bad.. Most likely the bank 2, or downstream is the culprit. But do both if doing one..

That said, have you checked over system to make sure all wiring, grounds, harnesses, etc. are in good shape. And have you wheeled in it thru water lately,

montanaman

12: Try clearing codes as the other guy suggested. I believe that when you pull the codes the first time, that resets your computer and starts fresh again.

15: Your year of XJ is supposed to have a sensor-driven speedometer, not a gear driven. It sounds like the guy you bought from installed an older T-Case that uses Gear-driven speedometer cable. Your computer is expecting information from the speed sensor and not getting it. Normally the sensor bolts onto the Tcase. I don't know if you can convert an older T-Case to sensor. I honestly don't think that getting the gear will get rid of your code. Does your speedometer work now? If not, it's because the previous owner didn't convert your speedometer to gear/cable drive to match the TCase he installed. Another possibility is he just didn't understand about speed sensors, and didn't connect it properly? I don't know ... you'll have to crawl under your vehicle and look for your speed sensor on a wire somewhere on the right side of your TCase. Also look at the numbers on the round metal tag on the rear of the case. One of those numbers--either the serial number or assembly number--will tell you what year your tcase was manufactured. Do a google search or look in a Chilton's manual. I forget how to parse those numbers.

21. First of all ... the previous post was misleading ... you only have ONE O2 sensor. Only 1996 & later XJs have 2 O2 sensors. There is a procedure for testing your O2 sensor with a multi-meter:

http://www.naxja.org/forum/showthread.php?t=1012701

Click on the link above and start with "EcoMike's" second post. That will tell you how to check your O2 sensor.

Good luck.

Gee oh Dee

Mine is under the dash just above my right knee essentially. Shiny silver box. I think most are there.

kissthis66

I disconnected the battery for about a half hr, hooked it back up and the codes are gone. I drove back and forth to work today and normally after about 5 min the CEL would come on but hasnt so far. *knock on wood* i think its fixed lol.

so back to topic at hand, would you buy a Chip for your jeep to help on gas/mileage/power/torq/etc.?