Ford fiesta 1300 cc imported from uk to Mexico, lately the car unexpected start to accelerate when stop and sometimes I had to cut the switch to avoid over rpms, I sended many times to the garage and they don’t find the cause because the fault is not always present, they change the oxygen sensor, work fine for a while then return, then they change the jack valve, (the one than regulate de rpm on low speeds) work for a while then return the bad function, any idea what could be wrong?, the map sensor, the mat sensor, the computer the jack valve again?

Rodolfo Cruz, November 2004

Hello Rodolfo, my name is Luis, in Mexico as well, but I write in english to be respectful to other readers. I have had the same problem several times. The first time, the Ford dealer in Saltillo, Coahuila took care of it, and explained to me that the Jack valve had to be replaced. The second time, about 20 months after the dealer replaced the valve the first time, the problem reappeared. I went to an independent garage in Ciudad Juarez... same diagnosis, same solution... replace the Jack Valve. Ran Ok for about 20 months. It is doing it again now, so I just bought the valve again. This time, I'll replace it myself. It doesn't look like it is complex. I know I have to disconnect the battery before removing the electric plug of the valve, and then unbolting it. I don't know if there is any calibration, or adjusting needed though. It doesn't look like it does, but if anybody out there knows, I would appreciate some comments.

Luis G. Guajardo, April 2006