240SX Auto Trans Shifting problem

[ILikeMy240sx]

This is my friend's 240sx with SOHC engines so I think that was 89~91... It has an automatic transmission that's having some shifting difficulties.

I does not up-shift until the car is reving at around 5500 RPM. Sometimes it seems like it doesnt up-shift until certain vehicle speed is reached regardless of engine RPM and the throttle position (why I have to drive the car to about 5500 RPM to reach that certain speed).

I ran the self-diagnose mode on the transmission by playing around with the O/D button and it did not give any codes because all the blinks were pretty fast and they were all same intervals. Also the transmission fluid is fine because we just changed the fluid.

Any thoughts?

[s13sr20chris]

check the fluid. that is a classic sign of low fluid level. engine running in park.

[ILikeMy240sx]

We checked the fluid level and the previous owner had put in crap load of fluid in there... way over the proper level so we drained it and refilled to the proper level so the fluid level should be ok tho...

[s13sr20chris]

oops, did not see that in your original post. try unplugging the dropping resistor. its by the airbox. its a little grey rectangular box thing with an electrical connector(2 wires iirc). that should max the line pressure. if that helps you know you need a pump or regulator or something. if not, you prob have a leaking clutch pack seal.

[onosqv]

When you say upshift until 5500, do you mean:

1) It feels like you are driving manually in D1, D2, D3, etc all the way up to 5500k

or

2) It feels like you are sluggish and slow and it is stuck in d3

and does it only do this when cold/warm?

When it does do it, is it like that the whole/rest of the trip, or just randomly?

[ILikeMy240sx]

Problem 1) as you described....

It does it ALL the time regardless of cold, warm, how much I travelled etc etc.

I will try unplugging that grey connector thing and see if that does anything.

[guyaverage]

Check your TPS (throttle position sensor). If that checks ok, read this thread:

zerothread?id=96505

[ILikeMy240sx]

guyaverage, thanks so much for that wonderful link! It was prob one of the most informative post Ive read here... I am going to go ahead and try that unplugging the rev sensor harness trick...

I hope this fixes his car so I can drive the dang thing around while I rebuild my SR.

thanks so much!