TheEvilBain_TDB

My 2002 GT Ive noticed my rpms seem to be sticking and going up and down. while driving and coming to a stop The rpm will stay at 2k for about 3 seconds then drop down to normal idle RPM also some times while coasting or at a stop it will rev up to 2k back down to 1.5k back to 2k and down to 1.5k again. After doing this for a while it will go back to idle.

My other issue is I have a 3inch x pipe with Magnaflow mufflers and no cats. When cruising on the high way in overdrive my Service Engine Light will come on. When I run the code it says Catalyst System Efficiency Below Threshold (Bank 2) why would it be saying only bank 2 when neither cats or on it and dosnt that only come on when your cats start to get plugged up?

school boy

is your rear o2 sensers turned off?

TheEvilBain_TDB

How would I find out? When I bought this car I found out who ever owned it before has done the underdrive pully's exhaust gears. So Im woundering if they got it tuned and shut off 1 sensor and not the other o2 sensor? There is two right one for each bank.

school boy

did you recieve a programer? if you did, you might be able to turn them off with that. if not, the o2's may still be on. i use to know where to take the car to get them turned off but i have forgotten. i have my own tuning software now. i know any tuning shop cn do it but for a fee. a auto parts store may but i dont know

TheEvilBain_TDB

I wounder if the local muffler shop could do it then again if I dont have any cats they probably wont even work on my car.

MU71L4710N

scratch all that. your problem has absolutely NOTHING to do with your 02 sensors. the rear 02 sensors do not affect the way your car drives in any way shape or form. they are only there to tell you if your cats are working or arent. my guess is you have MIL eliminators on your car and they can act funky sometimes (if you had a tune that had them disabled, there is NO WAY you would be getting a code for your cats not working unless you've disconnected the battery recently because that clears the tune off) . the mil eliminators i have on my car shut my CEL off for maybe 6 months, then it came back on so i disabled them with my tuner. you can ignore the CEL if you want because the only thing throwing that code does is put a yellow light on your dash. Or if you want it off, you can get new mils, or you can get a tuner and turn them off. if you know how to solder you can make your own mil elims for about 5 bucks at radio shack.

idle problems are 95% of the time your IAC valve. 70 bucks from ford for a new one and a child can replace it, its 2 bolts and a plug or so connected to your air plenum.

and about them working on your exhaust. they likely will not touch your exhaust at all, unless your having cats put on if you live in a state where cats are required. sometimes you can find mom and pop shops that will do work cuz they really dont give a **** but somewhere corporate like mad hatter won't touch it if its violating federal emission laws.

school boy

i wasnt even addressing his idle problem yet. and if his cats are gone, the owner before him could of clear the code to sell the car. you just said scratch that and repeated everything i said about the o2 sensers. but tbd, the above about the iac valve is correct

TheEvilBain_TDB

Thank you for all the info. So that IAC sensor going bad still wont throw my CEL light on? I think Im going to just buy a tuner because my battery has been disconnected. Also I notice my car dosnt seem to have that much power. I was told I have 3.55 gears I have underdrive pullies the exhaust dont and when Im in second gear at 2 to 2.5 k and I floor it it seems sluggish dosnt even kick me back in the seat. My fox body had alot more torque and power then my 2002 gt so something isnt right. I do thank you both for all your help

school boy

disconnecting the battery will not erase the tune, if so, what about everytime you get a new battery? i have had my tune in my car disconnected the battery to wire up more gauges. do you plan to do any major mods to the car? if you are, check with your local tuning shop to see what they use so when they go to tune your car, you will already have the correct tuning unit. if you plan to tune it yourself, check out sniper. i use it and like it

TheEvilBain_TDB

I just wanted basic bolt on mods for this engine to try and get the most hp and tq out of it. IT has 142000 miles on it im looking for a wrecked gt on coparts with low miles and plan on swaping engines then build up the motor with 142,000 miles on it. Is there a way to see if my car has been tuned or chipped. I would probably have to tune it my self only place around me that might do it is ford.