tango2020

Last month I bought an 04 GT with 59000 miles on it. It's in great shape and looks like the previous owner took great care of it. It doesn't appear to have any mods at all. I bought it from a dealer and it was a repossession. I have noticed that if I use 87 octane it tends to knock only when it's cold (sounds like the valves) when rpms are around 3k. With 93 octane ....no knock. Because it's a repo I was wondering if it could a tune in it and perhaps the timing is advanced...any way to find this out? I had a 95 gt and this car feels way stronger than my 95.

sweger

congrats on your car! i just bought my 04 in december. i cant help you much, as i immediately started buying mods and have very little time (2 days) with my car in its stock form, which ishow it was when i bought it. i bought a diablosport predator and installed the 93 octane tune for 2 weeks, then for the last 3 days i washome (on leave from iraq) i put hte 87 octane tune on it. with the 87 it ran great, and didnt feel like much power was lost but was definitely noticable. maybe someone more knowledgable will chime in.

03svtcobra12

well heres an idea, if the car was tuned to run on 91 or 93 octane it more than likely will not run great on 87, my cobra runs like **** on 87 and i will never put that in it, idk how you can tell if its been tuned without a tuner though

sweger

yeah my dad told memy car was running bad when i talked to him last...i asked him what fuel he put in. 93...thought he was doing me a favor even though i asked him to only put 87 in it. no harm though.

cliffyk

It is highly unlikely is would ping when cold and not once warmed up. At 3k rpm when you hear the noise are you cruising, or at or near WOT? If you are crusing and/or not under heavy load then it's not spark knock.

tango2020

Thanks for the reply guys. When I hear the pinging or knocking is when I start from a stop and as the car is going through the gears (Automatic) as the transmission is changing to the next gear. That is at moderate acceleration of course...The car is cold. It's almost like the moment where the load is off the engine between gears. I don't know if that makes any sense but I just don't know if I should be concerned. When the car is warm it is fine. It's bad enough that my wife noticed it so I don't think it's just me.

tango2020

Maybe I'm just paranoid. It runs great with 93 octane so maybe I should not worry and just drive!

max427

two options. there is still a notch in the balancer to check timing the old fashioned way, with a timing light. but i doubt the tune (if any) changed the base timing. so really you could either:
first option- get a friend with an SCT to identify your vehicle, if im not mistaken there is an option there to i.d calibration. then you could cross reference with someone else with a similar model to see.

second option- a dealer can check your calibration, and reflash to stock if u feel the need. but nothings free, that would be at least a $100 stop in my estimation.

SteveMasterZerox9

AS to if there is a tune. Was it inspected any time lately for emissions becuase chances are if it is tuned it probably would not pass emissions since regualr tunes generally turn off the rear o2 sensors and things of that nature!!!

max427

the car will still pass emissions. the monitors come up as N/A, not as not ran, so it will pass. just like a car without an air pump, the air pump monitor will run N/A. all is well as long as cel isnt on. trust me