DPS filter

Any warning lights or error codes?

Quite often if you don't have a means to read any error codes via the OBD2 port such as a Scangauge or Ultragauge you will have to get a dealer to inteogate the ECU for codes.

As John asked, any CRL (check engine light) on ?
Might be yellow engine shaped light or similar on dash.
This indicates a fault code is recorded, and usually with the basic OBD2 port reader, you can find the code easy enough, most advise the fault too, or it can be googled.

Are you getting any other issues besides lack of power ?
All dashboard features work ?
4wd lights etc ?

Check all fuses Stuart, these can cause all sorts of issues if you have one blown and don't realise it.
Eg. My Ranger had a blown Brake light / Horn fuse blown recently on the way home from a Madigan trip, turned out Mr Ford was smart enough to wire the TCM (transmission control module) into that circuit, an essential piece of electronics, and in a further brainstorm failed to note this in any wiring info.
The CEL / code came up on my reader, but alas all the issues associated with it were too complex for me to work out until the comfort and means of home.
Even the RAA at Coober Pedy were stumped.
900km run home in limp mode. Fun.

So check all functions on vehicle, gloves, other elects etc, if something isn't working, pull a fuse and check, remove and check all fuses anyway.

Oh and I think you mean DPF, diesel particulate filter ?
If this is the issue, you might need to replace, as many just throw a DPF warning light, and you just need to give them a good highway speed run to clear them.
Limp mode for this ? Haven't heard of it.

your vehicle won,t have a Diesel Particulate Filter too old
they are only on common rail engines think you will find
mechpete

Hi Stuart and Gunny, as your rodeo is a 1993 model, their will be no computers, ecu's, electronic's or expensive stuff. As the 2.8 is old school the problem will be
most likely mechanical eg. compresson, turbo or blocked exhaust, or fuel eg. pump, pick up, injectors or filter.
Cheers, Wayne.

With a diesel, first thing I would look at is blocked fuel filter.
Then check the air filter and ducting to the inlet manifold for blocking etc.

Then check for air in the fuel system being sucked in towards the injector pump, an air leak will knock off the performance of a diesel pretty quickly.
common problems are perished priming pumps that sit on top of the filter housing.

Do these have the bosch ve injector pumps on them, if so they can sometimes leak air via the throttle shaft O ring, they also have another fine mesh filter screen just underneath the idle stop solenoid that can also block up.

then look at turbo, injector pump etc, but cover the basics first.

hope this helps
Cheers

Trains

Stuart and Gunny
As your vehicle is a 1993 model Holden Rodeo 2.8 TD the only electronics that effect the engine operation is a computer controlled glow plugs, and an electric solenoid for engine start/stop. I am not sure what you mean about going into limp home mode as, as I recall, there is no such warning or operational system in these vehicles.
Any loss of 'get up and go' will come down to some sort of mechanical issue, and could be as simple as a blocked fuel or air filter, or even that there is a tappet adjustment required. That breed of vehicle is very much affected by incorrect tappet clearance, and yes I did own a number of 2.8td Isuzu vehicles. Old or poor quality engine oil will also be another possible cause, and only use 15/40 oil, do not be tempted to use any 'thicker' oil just because it may use some. When this engine was first released in the Jackaroo the oil spec was SAE30, and the use of multigrade oils caused glazing of the bores and oil useage.
Also any loss of boost pressure will have a marked effect on performance, so check all hoses and even the inlet manifold gasket (oil leaks from these areas would be a give away). Whilst a blocked exhaust is a possibility it is extremely rare, a leaking exhaust manifold to either head or turbo would also cause your problem.
And finally it may pay to have the injector pump timing checked, as I have found them to be out (retarded) by just a couple of degrees, and a reset has made a very noticeable change in the performance and fuel economy.
Hope this is of assistance.
Regards
Athol
Retired Motor Mechanic and past owner of similar vehicles.

Isuzu powered Dmax, Colorado and Rodeo vehicles do not have Diesel Particulate Filters as yet.

I'm another one for the fuel filter, air filter blocked, or maybe some air inlet hose is collapsing(if they have one) or maybe a collapsed muffler internals causing a blockage.
Diesels that old have minimal electronics and no engine management electronics.
So basically it is an air pump, they suck in as much air as available, inject a predetermined amount of fuel and bang, then blow it out the exhaust.
If it has lost its get up and go, it has a restriction on the inlet, or it is not getting enough fuel, or it has lost compression, or it has a blockage getting rid of it all.lol
So the last two posts,IMO were spot on.