Has anyone noticed a very noticeable difference in acceleration and responsiveness with the mustangs when the engine is "cold" vs totally warmed up? I've had my 2005 GT for more than a year and have always noticed that when it gets warmed up it is less responsive and slower than when its cold or partially warmed up but lately it seems the difference is more noticeable. I ignored it for a few weeks because the weather was so hot and I attributed it to air density etc... but lately its been in the 50's here in upstate NY (in the morning) and its still very noticeable. I have a JLT intake and a good 93 torque tune and when I first installed the mod's in June the difference between cold and hot engine performance seemed to be almost gone, but its back? Maybe its my imagination or maybe something in my cars computer has changed in the past month? I'll try re-loading the tune to see if it "resets" the performance. I just wanted to know if anyone else has noticed performance changes like this.
Thanks

 

I hate to say it, but yeah, I have noticed it too. Right after I fire it up (first minute or so), it just seems to have more bark and is more responsive to the loud pedal.

I too have the JLT2 CAI and a Bamachips tune.

 

Engine is tighter when cold. Knew a guy who ran at the track, would trailer the car and push it to the start line to keep it cold for the first run.

 

I asked Doug from BamaChips about it. He has an '05 GT also, but I got the impression he hasn't noticed it in his own car. (probably because it's always in the shop getting new mods ) Anyway, he said it probably has something to do with the fuel loop being open for the first few minutes of operation. Basically there's tons of fuel being dumped into the engine with little control from the computer. I asked about adjusting my tune so the car would run like that all the time, but he said even if he could, the gas mileage would drop like a rock.

BTW, my car does it too. As well as my '03 GT. Ideally there should be some way to make the car run in that "initial" mode with the flip of a switch. That way for everyday driving gas mileage would be OK, but when you really wanted the power, it would be at your fingertips. Must be nice to have a diesel truck nowadays since they can do that with an aftermarket tune.

I am very interested to hear what others have to say about this as it's always bugged me to know my car could have so much more power.

 

If you keep dumping raw gas like that into the engine you will:

1) burn out your catalytic converters

2) accelerate the cylinder wear since the fuel would wash the oil from the cylinder walls.

Probably not a good idea to have that mode going for very long. It's like a choke setting on the old carbureted cars - smelled like hell and was bad for the engine, but necessary for those cold starts.

 

Ive noticed it to. Especially on cold mornings or late at night after work. I can spin the tires nto even meaning to.

 

funny, i was thinking about this today on ym way home. There is a nice stretch of road right near my house and going to work i hit it hard and the car flyes, on the way hoem though, I hit it and its not the same.

 

someone who knows more about this will chim in im sure but heres why this is happening as best as i can explain

cold air is more condenced so more is fed into the engine when its cold thus giving us more hp vs warm air being brought in after it warms up or if its a hot day vs a cold day, thats why a ton of people use co2 or nitrous in there intake or on there turbos to force cold air into the engine to increas the hp

im pretty sure thats why we feel a difference between cold weather driving and hot

 

I notice it as well... I'm sure the fast idle plays a factor with is as well

 

That can also be attributed to cold tires.

 

I used to think it was the cold air, but the difference is there no matter what the ambient temp is. It's when the car itself is cold. No whether it's because of something the computer is doing or because the engine bay (air inlet tube, intake, etc) hasn't heated up yet, I don't know.

If it's because the engine bay hasn't heated up that just goes to show you how much we would benefit from a true CAI/ram air setup... IF someone would ever make one.

 

Thanks for all of the replies everyone. I wonder if anyone has dyno'd their car with a cold engine vs when they let the engine warm up?

 

I wonder if this stuff would help.
http://store.summitracing.com/partde...5&autoview=sku

 

You could try the "slowly press the accellerator to the floor right after the key is turned to the on position" then turn the key off, wait a few seconds then start the car" procedure. It seems to help my car just a little. Not sure what is going on but I read it here in the forums last Feb or March. My car computer is not modified at all though.

 

I refuse to believe its anything more than cool air being denser than heated. once the engine has been on for a few minutes the air under the hood drawn into the air box is warmer, less dense, makes less power.

 

I ended up reflashing my 92 octane torque tune for my JLT (the same tune that I was already running). I swear the car runs better again and the power difference has diminished to what it was when I first loaded the tune 2 months ago. I don't understand it but I will reflash againg if the power difference returns in the future since its so easy. I also did some searching on this forum and found some others have done the same thing (reflash) and gotten similar results last year.