Big Red

Hey everyone, I sold my 06 V6 stang, now Im driving an 03 V6 Ranger with a manual tranny. My truck has the same 4.0L SOHC engine as the stang, but Im having a weird issue with it that I dont remember having with the mustang, but I have heard of it before I think.

Basically when I go to upshift my truck, I let go of the throttle and push the clutch pedal in, but instead of the RPMs dropping right away, they sometimes hang there for a second or two and then start to drop, other times it will just drop really slow. I let the dealer look at it and they replaced the Idle control valve but iut didnt fix it, so they said they think its an emissions control, the engine burning off excess gas to doesnt spit it out the tailpipe. It annoyed me so I went and replaced the throttle position sensor and the PCV valve, but its still going on.

So I just wanted to know if any of you folks experienced the same thing with your Mustangs with the 4.0 SOHC, I dont remember it with mine, but I havent driven it since september, so I dunno.

billybix76

Since no-one else is helping out I will dig in...

Its most likely the computer tune or O/2 senors. The ECM will, on a stock tune, "feather" the throttle and fuel flow to make smoother shifting, up & down, possible for grandma...and you may have bad overrich condition caused by failing upstream (front of the catalytic) O/2 sensor. I had a 98 Ranger did the same thing & changing the upstream O/2 sesnor helped the computer sort things out...And by the way the 4.0's in the 05+ Mustang and 03 Ranger only share basic block design and displacement, they are vastly different engines.......

luck!