[Dr Donut]

First off I would like to say hello to everyone, after visiting this site a few times I decided it was time to register and join the group. I recently purchased a 98 gt (my first mustang) and have a few questions about the 02 sensors. Getting cel for all 4 02's, the rear two are not hooked up, the front 2 are so I am assuming that they are bad. Being a newbie to the mustangs I wanted to get some input before I start changing things. The car runs pretty good, just seems to be a little off sometimes like the A/F mixture isn't perfect. Wanted to know how important the rear 02's are to this as I have no cats, and the best way to proceed in remplacement etc...

List of mods ( that I know of)

2 1/2" duals w/ xpipe, no cats
cone filter, (not a cai)
fuel maximizer chip(thinking this does more harm then good)
75mm edelbrock tb
ford racing wires w/ e3 plugs (new)

Just want to get the girl running right for the summer. Planning on doing a build on the engine this winter. Sorry for the absurdly long post and thanks for the help in advance. (p.s. car is an auto for now)

 

[Shelbydog!]

If you are running catless the rear o2s need to be shut off via tuner or MIL eliminators. If you are still having a/f it could be a number of things. I would take that "fuel max chip" out asap and see what happens.

 

[Dr Donut]

was thinking the chip should be removed, will see what that does, I was planning on getting a tuner in the near future, but i may try the mils eliminators w/ new front 02 sensors, till then as the tuners are a bit pricey.

 

[nkausch]

The mil eliminates cause my buddies 96 to run extremely lean. Dunno why. So just a heads up there.

 

[Dr Donut]

Seems like running without cats causes a lot of issues...

 

[drakkhen20]

not really, you just have to have the right equipment if you plan on going that route. take that stupid fuel maximizer crap off. you have a aftermarket throttle body on there and a fuel saver chip. that doesnt do any good together because the chip messes with the a/f ratios and your timing advance/retard. go get a handheld tuner like sniper or sct. id recommend sct as you can shut off the rear o2s or get a tune that will compinsate for the lack of cats. also change both your front o2s just to make sure thier not bad so that issue is eliminated.

 

[1996 GT]

MIL eliminators and new o2's up front. That should solve it.

 

[98REDGT]

MIL eliminators and new o2's up front. That should solve it.

I have a 98 as well. Catless x pipe into flowmasters. Mil eliminators on rear sensors and i have no problemms at all. Change both front o2s. And put in some copper motorcraft plugs and youll be good to go. You can find how to make mils on line. I made some, but my car came with ones from american muscle already.

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[97S281]

The mil eliminates cause my buddies 96 to run extremely lean. Dunno why. So just a heads up there.

Does he have them on the front instead of the back? The rear sensors only report the catalyst efficiency to the cpu. They don't control the AFR, that is done by the front sensors.

 

[Dr Donut]

Ok I'm going to order the mils eliminators from AM in the next week or so, and remove the chip the previous owner had installed as well as replace the front o2 sensors. AM has the ntk sensors for 50 bucks, summit has the bosch for 33, don't think I want to spend the money right now on oem ones. Just wondering which would be better and if I could use the old front ones for the rears as I would be running the mils and both sites list the sensor as front and rear. Thanks for the input as well

 

[Hotshot_98GT]

DO NOT WASTE YOUR MONEY ON MIL ELIMINATORS!!!! Just save up a little more and get a tuner!! You can turn off the O2s AND gain a few hp

Seems like running without cats causes a lot of issues...

:no been running catless for 4 years strong!

Does he have them on the front instead of the back? The rear sensors only report the catalyst efficiency to the cpu. They don't control the AFR, that is done by the front sensors.

Yeah seriously! The only thing no rear O2s will even cause is a Check Engine light. They don't control anything, just monitor the catalytic efficiency! :yes

 

[Dr Donut]

DO NOT WASTE YOUR MONEY ON MIL ELIMINATORS!!!! Just save up a little more and get a tuner!! You can turn off the O2s AND gain a few hp

Kind of what I was leaning at to begin with, will just do the o2s and remove chip for now, I'm pretty sure i can find a thread on a good tuner, SCT im sure is the way to go but they have a few different models listed for these cars, Ill have to do the research and see which is best, I already know I'm not spending 800 on the touchscreen one

 

[nkausch]

Does he have them on the front instead of the back? The rear sensors only report the catalyst efficiency to the cpu. They don't control the AFR, that is done by the front sensors.

I dunno. It started right after we put them in and yes we are positive there not mixed up. Although to be fair it could be something else all together( and most likely is)

 

[Hotshot_98GT]

Kind of what I was leaning at to begin with, will just do the o2s and remove chip for now, I'm pretty sure i can find a thread on a good tuner, SCT im sure is the way to go but they have a few different models listed for these cars, Ill have to do the research and see which is best, I already know I'm not spending 800 on the touchscreen one

SCT and Diablo are supposed to be good from what I've read. I have a dyno tune though, so I'm not positive. Good luck

 

[Dr Donut]

SCT and Diablo are supposed to be good from what I've read. I have a dyno tune though, so I'm not positive. Good luck

I would like to do a dyno tune but for a car with just bolt ons it seems rather pointless. That will come after the motor build

Again thanks for all the help and input guys, seems like a real good community on this site.

 

[Dr Donut]

Happy to report that after removing that damn fuel max chip and letting the battery sit unplugged overnight. After driving about 30mi or so I am now only getting codes for the rear o2's, car seems to run much better, still going to change the plugs over to the motorcrafts, and I need to get a new battery will prob grab an optima.

 

[bigjohnstud4200]

I just went to a catless prochamber; i was running with the rear o2's hooked up until I received my email tune for my predator. While running with rear o2's hooked up, I had a noticeable odor of unburned fuel. It wasn't extremely bad, but I noticed it every time I got out. Now that my tune is installed, the smells is rarely there. I think the MPG's are also increasing however. New front o2's were installed.

 

[Dr Donut]

An sct is next on the list after some front tires.

 

[xandraxal]

Id go with ngk tr6 plugs

 

[1996 GT]

Id go with ngk tr6 plugs

I'm not sure why most people are convinced TR6's are going to be better for your car when your a/f mixture is virtually the same and compression is the same. Run a TR55 is you want to run a copper plug or a TR55GP for a platinum.

If you did a PI swap and bumped your compression, or head work, boosted or using nitrous then yes i would use a TR6. :yes