Tr Magna Gear Changes Options

[eanott]

Hey there

I've got a 91 TR magna. When driving it has started to change gear all on it's own. It can drop back from top to 1st or second, it almost conks out.

I was told it could be the computer transmission controller thing (not sure of its real name)

I disconected the battery and left it for a minute and it drove OK for about 10 minutes. Then it started playing up again.

Any ideas?

Thanks

[KiT TeUnG 2549]

Its hard to say , a bad Throttle Position Sensor can also do teh same thing. If it seems to be shifting irratic and premature and so on , the TPS can cause this. now , when decelling , does the engine feels rough and as if its going to stall?

[eanott]

yeah. quite often i think it will stall, it did in reverse the other day. when idling it stutters as well

[eanott]

yeah. quite often i think it will stall, it did in reverse the other day. when idling it stutters as well


I disconnected the TPS and went for a short drive. The sudden jumping between gears didn't happen but when I got to about 40 km/h it started to rev higher. I assume it dropped back a gear, but it was much smoother that it had been. The car then changed back through the gears as normal.

This to me suggests that the TPS is playing some role but there might be something else as well.

Thanks for your advice. I will see what happens when I replace the TPS.

[KiT TeUnG 2549]

Yes , The computer reads the varying throttle position and helps the engine to adjust fuel delivery and fuel spray. Especially if it reads the throttle is closed while yu are in gear it helps the computer to adjust and open the Idle Air Control Valve to help keep the engine running while the throttle is closed and engine under loads such as being in gear , AC on , turning etc.

Also when driving The computer reads the varying signal of the TPS as its being opened and closed , to help accurately place and adjust shifting , as in down and up shifting in certain situations , as in accelerating and slowing down. A bad TPS can make teh car have uneven and irratic shift points , rough idle etc.