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Discussion Starter · #1 ·
Hey everyone :D

I bought a used 06 gt and everything was fine till a month later the engine light came on. Went to auto zone to have it checked out,they said my 02 sensor was slow to respond.So i replaced it and reset the cpu.Then a week later the engine light came on again.this time 3 of my 02 sensors were slow to respond.So here is my question.Could the first owner of the car got into the cpu and mess it up?other things i noticed are my car idles at 1000 rpm and i can't turn posi-trac off and my car runs lean.you can smell it at times inside the car.

thanx
 

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Sounds to me like the car has a performance tune in it. Did it come with the hand tuner? Does it have long tube headers? What mods? You may end up having to go to the dealer for a re-flash back to stock if it has a tune in it and no hand tuner.
 

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+1 ^. you need to find out if it was tuned, kinda what it sounds like.
 

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Hey everyone :D

I bought a used 06 gt and everything was fine till a month later the engine light came on. Went to auto zone to have it checked out,they said my 02 sensor was slow to respond.So i replaced it and reset the cpu.Then a week later the engine light came on again.this time 3 of my 02 sensors were slow to respond.So here is my question.Could the first owner of the car got into the cpu and mess it up?other things i noticed are my car idles at 1000 rpm and i can't turn posi-trac off and my car runs lean.you can smell it at times inside the car.

thanx
Were the any of the 3 sensors that threw a CEL the same one as you just replaced or the other 3? Yes your idle is a little high. Your posi-traction can't be turned off, it is a mechanical function that works based on the torque applied to your axles. Unless you are talking about an E-Locker rear end. And how do you know it's running lean? Are you getting any detonation/knocking when you put a load on the engine. If you are smelling unburnt fuel in your exhaust it is probably running rich, not lean.

Conjecture: The bad O2 sensors is causing the car to run rich. Or the CPU detects a problem with the O2 sensors and is running it rich to be safe like on cold start up before the sensors would get up to temp.
 

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Discussion Starter · #5 · (Edited)
Were the any of the 3 sensors that threw a CEL the same one as you just replaced or the other 3? Yes your idle is a little high. Your posi-traction can't be turned off, it is a mechanical function that works based on the torque applied to your axles. Unless you are talking about an E-Locker rear end. And how do you know it's running lean? Are you getting any detonation/knocking when you put a load on the engine. If you are smelling unburnt fuel in your exhaust it is probably running rich, not lean.

Conjecture: The bad O2 sensors is causing the car to run rich. Or the CPU detects a problem with the O2 sensors and is running it rich to be safe like on cold start up before the sensors would get up to temp.
the o2 sensor i replaced was one of the three.Your right i meant the car run rich.I'm almost certain the car has been tuned.The car came with a JPL cai and OBX long tube headers.Do the hand-held tuners come with stock tunes or just the high performance?one more thing,car only has 29k miles
 

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Usually a hand held tuner comes with several octane performance tunes. As soon as you install a tune the unit becomes married to your vehicle until you reinstall the factory tune. A lot of people will install a tune and sell the hand tuner which is useless to the buyer except for maybe checking trouble codes. If that's the case then your car is unable to receive another custom tune until that hand tuner is plugged in again or you have a dealer re-flash the PCM to stock, then buy another hand tuner if you want a new performance tune.
 

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Discussion Starter · #7 ·
Usually a hand held tuner comes with several octane performance tunes. As soon as you install a tune the unit becomes married to your vehicle until you reinstall the factory tune. A lot of people will install a tune and sell the hand tuner which is useless to the buyer except for maybe checking trouble codes. If that's the case then your car is unable to receive another custom tune until that hand tuner is plugged in again or you have a dealer re-flash the PCM to stock, then buy another hand tuner if you want a new performance tune.
did not know that thanx.
 

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Discussion Starter · #8 ·
My car came with a JLT CAI if i go to the dealer and place stock tune back on car will car start?
 

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If you flash it back to stock you will need to put the factory air box back in even though it will start and run. Stay off of wide open throttle with the JLT on there with the stock tune.
 

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Maybe I'm missing something. I don't think the OP has a tuner, does he? It sounds like the original owner had a tune it and than removed the tune and put the car back to stock. Now with those mods you are running very lean without a doubt. The JLT and the longtube headers need to be tuned for ASAP! It's not safe to be running it like it is. Also the reason why you're getting that error is because of the longtubes. Once you get a tune it'll be fine. What you need to order is a custom tuned SCT Xcal3 and you'll be able to tell the tuner what kind of mods you have and he'll write the tune for them.

VMP Tuning - Buy Ford SCT & GM Custom Handheld Flash Tuners Performance Economy Towing: Custom Tuned SCT X3 Flash Tuner for Ford Vehicle from VMP
 

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I was thinking the same thing except that it's common for guys to install a custom tune, then sell the tuner (locked) for code reading purposes. Either way, he needs to get the stock tune back in, then retune for the CAI ASAP like you stated.
 

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Also, shouldn't the rear 02 sensors be turned off in the tune because of the long tubes?
yet he's still getting a code from at least one of them.
 

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I will have an unlocked Diablo Predator Tuner here in a couple of weeks if you are interested.
 

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Discussion Starter · #17 ·
Picked up sct tuner today from Modular Depot. They did a custom tune and it fixed all the problems. Thanks everyone.
 

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Thats good that you got the problem solved.The fact is that people remove their tunes from the car because dealerships and so on don't give extra cash for a hand held or the owner plans to reuse the tuner on another vehicle.One of the downfalls with buying a car thats modded you never know whats up with the tune.By the way where did you purchase your sensors from and how much were they.
 

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Discussion Starter · #19 ·
Thats good that you got the problem solved.The fact is that people remove their tunes from the car because dealerships and so on don't give extra cash for a hand held or the owner plans to reuse the tuner on another vehicle.One of the downfalls with buying a car thats modded you never know whats up with the tune.By the way where did you purchase your sensors from and how much were they.
o2 sensor were from autozone $60.Only replaced one.
 
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