online manual

[Claude]

http://www.scribd.com/doc/26457170/1991-Ford-Festiva-Manual

this has a lot of good info, just thought if you havent already found it.,

[Levitan]

I think 1.3 starts at about page 100.

[JohnGunn]

WOW! What a valuable find. It will take a while to get comfortable with it, but already I've found something extremely interesting.

In the following picture taken from page 149, they give resistances for the full range of movement of the throttle. But the footnote says, "Capri only. Festiva uses throttle position switch."

When you look inside a Festiva TPS there appear to be only two switches to signal when the throttle is fully closed or fully open. In addition, there is only one wire going from the TPS to the computer. Could it be that our TPS only signals those two conditions and can't be responsible for all the driveability problems it is commonly blamed for?

John Gunn
Coronado, CA

[sipderdoc]

thanks!! I was looking for that manual

[FB71]

WOW! What a valuable find. It will take a while to get comfortable with it, but already I've found something extremely interesting.

In the following picture taken from page 149, they give resistances for the full range of movement of the throttle. But the footnote says, "Capri only. Festiva uses throttle position switch."

When you look inside a Festiva TPS there appear to be only two switches to signal when the throttle is fully closed or fully open. In addition, there is only one wire going from the TPS to the computer. Could it be that our TPS only signals those two conditions and can't be responsible for all the driveability problems it is commonly blamed for?

John Gunn
Coronado, CA

yes John, our TPS only signals closed throttle and wide open throttle. However, if misadjusted, the idle switch will not close, and the PCM will increase IAC, advance spark, and raise injector PW slightly, expecting to see a significant change in VAF. All of this causes idle issues. This is because in closed throttle and WOT, the PCM is in open loop mode, ignoring the O2 sensor, and working only off of built-in look-up tables. In part-throttle mode, its in closed-loop mode, watching and responding to the smallest changes in the O2, which will drive idle to be erratic.

[Claude]

hope it comes in handy

[JohnGunn]

yes John, our TPS only signals closed throttle and wide open throttle. However, if misadjusted, the idle switch will not close, and the PCM will increase IAC, advance spark, and raise injector PW slightly, expecting to see a significant change in VAF. All of this causes idle issues. This is because in closed throttle and WOT, the PCM is in open loop mode, ignoring the O2 sensor, and working only off of built-in look-up tables. In part-throttle mode, its in closed-loop mode, watching and responding to the smallest changes in the O2, which will drive idle to be erratic.

Thanks, Jim. There's no substitute for someone who really knows.

John Gunn
Coronado, CA