High rpms

[heyrey]

I have a 89 240sx. The car sat for a couple of years I would start it periodically.I purchased a new battery, changed the oil and I drive it daily.What I have noticed is that when I am on the highway doing 60+ mph the rpms are between 3000 and 4000.

Any clue what the problem could be?

[DamonDread]

Single Cam?

[heyrey]

I'm not sure, How can I tell?

[SirSilvia]

mine does that too, I have a SOHC '89. I think it's the overdrive trying to pick in between the better gear. It's close to it's calculations for when it needs to shift (the right speed, RPMs, force against car like up hill or acceleration)

I might be talking out of my arse but this is what I gather. And of course I assume its automatic like mine is.We all know:1) If you are going up hill, there is a greater amount of force against the car because of the uphill climb so the RPM problem won't be there since the car is shifting. 2) Obviously while accelerating it's shifting because of the demand for more speed and such.

But on a near level road with consistent speed demand equals almost no additional load on the car. The Automatic transmission reaches a certain point where it either shifts or stays in gear, and it can't decide and make up it's mind.

OR

I was thinking my 4th gear is out and its trying to shift into it. Since I beat on my transmission pretty hard.

[numbnuts240]

I'm not sure, How can I tell?

it's an 89, it's definitely a single cam, unless it's been swapped. is it automatic or manual?

[heyrey]

auto, original engine

I don't remember it being that high in the past.

[TroubleBound]

I have a SOCH 89 Manual and i feel like mine does this too. I won't break 70 on the highway cause my car sounds like it wants to die. If im really hard on my car too and then come to a stop like at a red light, my idle is like 1500rpms, like 750 more then the 750 it is when i just get in it and start it. But after i sit at the light for like 10 seconds it slowly goes back down to 750. Its weird i don't like it. I want my DOHC back and my quiet fan. For some reason my fan is LOUD.

[SirSilvia]

750-900 is the normal Idle RPMs. Its higher if you have the heater/AC on.

[nissanman04]

Did you accidentally switch the overdrive off?

[SirSilvia]

Did you accidentally switch the overdrive off?

yeah op, that too.

or is it switching between 3-4k?