Nissan Repair: High rpms and excessive fuel consumption, nissan liberty, automatic gearbox

Question
QUESTION: Hie
I recently purchased a used japaneese nissan liberty 2.0 cc 1999 model.On accelerating the car goes to revs of more than 3000rpms for speeds as low as 60km/hr.The vehicle cannot get to 140km/hr unless fully depressing the accelerator pedal,and by that time the revs will be around 7000rpms with a high rev sound always.A  computer diagnosis scan was done on two separate occasions, and in both instances the reports were saying that everything is normal.The exhaust does not produce any visible black smoke.Sometimes the gears take time to engage, and the light for power (normally activated by the power/AT/Snow button) frequently lights up even when travelling at low speeds.I have compared the way it is consuming fuel with similar nissan liberty cars and have realised that it is consuming double the amount of fuel especially on highways for speeds as low as 100km/hr.I have had the car serviced on several occasions with the filters,oils and plugs being changed.The last service included changing the ATF as well.One mechanic was talking of gear slipping with another suggesting the master solenoid in the automatic gearbox but I failed to understand the problem as their suggestions seemed conflicting.

Your advice will be greatly appreciated

Thank you

ANSWER: Hello -

This sure seems like the transmission is slipping. It would not show up as a trouble code, so you will not find it in a scan.

The only cure for this is a transmission overhaul. I am assuming you have an automatic transmission.

If you have a manual trans, then it is the clutch plate, disc and bearing that should be replaced.

Hope this helps -
aloha
calvin

---------- FOLLOW-UP ----------

QUESTION: Thank you for the prompt response.It is indeed a 4-speed automatic transmission.Is it possible to replace the gearbox with the one for a nissan primera, and what effect does it have on the overall performance of the car?I am in Botswana, and the gearbox for nissan liberty is not easily accessible.

Answer
Hi Hie -

The best thing is to replace with the exact same model. I know it is hard to find, but then a lot of times, although the mounting matches up, you may not have the compatibility computer wise and the Check Engine light might remain on.

I know it is not what you want to hear, but just trying to save you some time and money.

Hope this helps -
aloha
calvin