Loss of power at high rpm/high speed

[EthanJ24 Lurker Find all posts View Profile Close EthanJ24]

Hi,

I recently bought a 2005 Prado Grande Automatic Diesel (KZJ120R). I’ve put it into my mechanic and had a bunch of work done and a tune up and she runs smoothly around town but I’ve just recently taken the car on my first long trip. I find getting up to speed on the highway (110kmh) is no problem but she really struggles with anything more. The few times I tried to overtake, I’d accelerate hard and it would go from 2500rpm to 3500rpm but not really gain any speed and it would struggle at times maintaining speed up hill even with the extra acceleration.

Any suggestions?

Cheers

[GEEEXL Member Find all posts View Profile Close GEEEXL]

sounds absolutely normal

what was your last car?

this is a > 2 ton car with a very old-school diesel first seen in domestic cars from 1993, they are slow and thirsty

[Brett1979 Avid PP Poster! Find all posts View Profile Close Brett1979]

Very normal for an underpowered 4cyl 2 ton 4wd. We have a 150 series diesel at work with a few yrs on it & it’s a pig to drive at hwy speeds compared to my 120 petrol. No responsiveness & no guts around 100kmh. Similar to my old 90 series really.

[adrian5800 Advanced Member Find all posts View Profile Close adrian5800]

In standard form the KZJ120s are pretty breathless over 3000rpm, especially if the intake manifold is caked up with EGR carbon as well. The standard cast dump pipe on the back of the turbo is quite restrictive compared to the rest of the exhaust system. With a freer flowing exhaust, dump pipe and a bit more boost they can go quite well for a heavy old school diesel. Mine goes well but also is chipped and runs 18 psi boost.

[Tony from West Oz Lurker Find all posts View Profile Close Tony from West Oz]

Hi,

I recently bought a 2005 Prado Grande Automatic Diesel (KZJ120R). I’ve put it into my mechanic and had a bunch of work done and a tune up and she runs smoothly around town but I’ve just recently taken the car on my first long trip. I find getting up to speed on the highway (110kmh) is no problem but she really struggles with anything more. The few times I tried to overtake, I’d accelerate hard and it would go from 2500rpm to 3500rpm but not really gain any speed and it would struggle at times maintaining speed up hill even with the extra acceleration.

Any suggestions?

Cheers

If you have replaced the fuel filter and it is still the same, then you could have an issue with a leaking priming pimp diaphragm on the fuel filter housing.
I had the same issue and after my mechanic replacing the injector pump and injectors, the problem remained. I put a clear plastic hose on the fuel pipe from the filter to the IP and it had lots of air bubbles in it. I then put rhe clear hose in the fuel line from the tank to the filter and it had no air bubbles in it. I have a replacement fuel filter primer pump / filter housing on order for it.
will advise outcome when I fit it.