Saleen05797

I was talking to my installer/tuner (after I had a bad experience with a previous shop). The original shop has installed superchargers on a lot of mustangs and I don't think ever had this problem. My car stumbles when it is cold. It doesn't want to move at all. My tuner said everything checks out fine i.e. fuel pressure, fuel pumps, injectors, etc... but I believe he said the voltage or something drops to 0 when it is cold. He's still working on pin-pointing the problem and I'm waiting on a response to double check what is dropping to 0. Has anyone else had this problem? I have a 2.4 KB that's intercooled with a KB Boost-a-pump and 60 lb injectors. Besides that, stock engine. The problem goes away when the car heats up to normal temp. TIA

hammeron

is this a custom tune or the KB tune

Saleen05797

It is a custom tuned, but it has been tuned by 2 different shops, multiple times, and the problem still persists.

hammeron

ok. well my best guess at this
point, is intake air temperature sensor
or something with the throttle position
sensor

do you get any trouble codes at all

mygt500

Funny this was brought up. Mine does the same thing most of the time after my Whipple install and tune. Everything checks out fine and I too have 60# injectors. I think it has to do with the injectors and a sensor when cold. I solved the problem by letting the car warm up for about 10 minutes before driving. Have not had time to take back to the installer/tuner and most likely wont this year as I am getting her ready for winter and her long nap and will start in the spring. Any help would be great. Oh and I do not get any trouble codes and after warm up she is a beast!!!!!!!!! Hammer-I pulled 10 more RWHP out of her on a recent dyno run to make sure she was fine and forgot to mention this small problem. So she makes about 465 when the weather is in the 50's- 60's and 65 % hunidity.

Saleen05797

I do not get any trouble codes. Would the o2 sensors have anything to do with it? My previous installer mentioned something about them going bad, but I can not trust him anymore.

mygt500: mine is fine if I let it warm up too. I need it fixed asap so I will let you know what the problem is once we get it solved. I drive my car in the winter sometimes when the roads are clean...

mygt500

Thanks PM me too if you remember! I am all over the place and bookmarked the thread so I can get to it sooner than later J (mygt500)

hammeron

well as a reference, i have the stock whipple
supplied injectors (39's i think....) and the FRPP
tune.....i don't have the stumble issue


here is something out of the haynes manual:

"The PCM uses the data from the upstream oxygen
sensor, to calculate the injector pulse width."

Saleen05797

So does that mean it possibly could be the o2 sensors?

hammeron

well, since both you and mygt500 have the
same issue, i have to think it's the tune....

it just seems unlikely, that both of your O2
sensors would fail around the same time frame....