Hello,i don't post in here much but thought i would give it a shot.

I have a 4.0 manual 5 speed mustang and have been having rpm issues again.I have xcal/tunes,and i have tried clearing it back to stock then reloading the tunes.This seems to have worked for awhile the first time,then the issue came back after a few weeks.Trying the same reload doesnt work at all now.The issue is when i am coming to a stop,the rpms drop to 500 and nearly stall the car.

If i am in 1st gear with clutch depressed or into nuetral makes no difference.I watch the rpm needle drop down then up sometimes twice over,then acts like it finally catches up and gets back to the 750 rpm range.It is quite annoying.

I am ruling out that it is a tune problem becasue i have tried tunes from 2 different tuners,and this issue comes up.Also,this was a non issue at one point.So,what can i check or what would cause this?I have under 5k miles on the stang,thanks- I am avoiding the dealership like a plague///

 

Sounds like a problem others were having on their GT's, with the throttle body going bad. Could be related.

 

What happens in stock settings?

 

Thanks for the feedback.I don't really know what happens at stock settings.I have had the xcal,then jlt xcal combo since under 500 miles.What i meant was that i set it back to stock first,then immediately loaded another tune.That ensured that all prior data was wiped out for sure,and was just an added measure to try and resolve this.The odd thing is it doesnt do it each and every time,but when it does,it seems to keep doing it until perhaps the next start up.

In addition i have noticed there are some days i can go right out of first gear with no gas and i'm fine.Other days,i buck doing the same exact thing at same rpm,so i have to add gas for a smooth takeoff..I just don't get that,like the car has it's own personality and moods,lol-

 

Yea this sounds like a problem in the drive by wire unit on the throttle body. I'm suprised it hasn't thrown any codes yet. The way to fix it is convert everything back to stock and tell the dealership to check it out.

Buying an aftermarket throttle body will reuse the stock sensors. That's IMO the problem. They have done funkier stuff than that before.

CR
Tillman Speed

 

ok,i spose i will have to visit them.I hope they don't try and blame my other mods for anything,lol.I also have gears,true trac,alum driveshaft,springs,lcas,etc..Glad i don't have the x-charger on yet,lol