Rolling Road Test

[mjpetersen]

Last week I took the plunge and got a Power Box installed in my 97 LWB Maverick TDI. I originally decided to get the Power Box because I tow an equipment trailer with a mini-excavator and I was looking for more get-it rolling power. Low end grunt to get a load on its way, is what was promised with the power box by Vtech. After the install they did not have time to put it on the rolling road (Dyno) to see the effect of the box on the power. Today I actually got the test done and I have mixed feelings about it. :nenau

Disappointment , in that my truck is just weak. Without the box it is developing only 81 hp and 167.3 Nm of torque. No wonder I needed more power--my Mondeo was better. So now I have to try to find out why my truck has no grunt. It is developing about 2/3 of what the TDI should be 81 instead of 125 hp.

Happiness, in that the power box really does help with the optimal setting increasing the output to 110 hp and 236 Nm which is a 30 hp and 59 Nm torque increase. That is a very significant improvement and gives me great hope that when locate and fix the problem there should be a great kick in the power department.:sly

Both HP and torque fall off significantly after the peak, and it should not--it should be more flat before dropping off. So now I just have to find out why?

I have eliminated the EGR and flap in the intake, There is a new K&N filter in the original filter housing. I see that there is a small leak at the rubber hose connection at the inter-cooler, I have not checked if I have a mini filter, so that is something I should do. The fuel filter was new in January. I have cleaned the MAF (Hitachi). I will have to take a bit of time to pursue this and I do not have time right now. But it is going to be on my mind until I do.

Advice gladly accepted.

Mike

 

[stinka]

is that power figure adjusted for transmission losses ?

 

[makeitfit]

As your power curve falls off after 3000 rpm it's probably not the maf as at that point there's so much air coming in it's not doing anything. So I'd be looking at fueling issues, pump, filter and poss pressure relief valve. Check fuel lines.
Turbo boost level could do with measuring ie the waste gate actuator could be set or become low. About 12 psi I think it should be :thumbs
You could also plug in a lappy and do a live data log of sensors to see what's going on in real time.
Good luck :sly

 

[mjpetersen]

I forgot to ask about transmission losses, but I thought of it. I think that the computer compensates for it, but how much and how would it know that? :nenau

Mike

 

[mjpetersen]

I have been thinking of the pressure relief, because sometimes I do have to crank it a bit before it fires when it is cold. I read in a thread here somewhere that is a classic sign of a leaking relief. So that is something that I will check.

Mike

 

[solarman216]

I have been thinking of the pressure relief, because sometimes I do have to crank it a bit before it fires when it is cold. I read in a thread here somewhere that is a classic sign of a leaking relief. So that is something that I will check.

Mike

If you are talking of pressure relief of the turbo then this will have absolutely nothing to do with cold starting, the turbo will not even be spinning at this time let alone producing pressure, poor cold starting will be more to do with glow plugs, or poor fuelling/pump, Rick

 

[makeitfit]

Diesel pump Pressure relief valve. It's meant to keep a certain pressure in the pump in order to squirt the juice through the injectors I thought. If it's weak then there wont be enough fuel for hard work. Apparently you can restrict the return fuel line to check if it's doing it's job properly. So if you get more fuel after restricting the return then it's the relief valve. All of 17 quid :thumbs

 

[solarman216]

Whoops, misunderstood, Rick

 

[arcascomp]

Diesel pump Pressure relief valve. It's meant to keep a certain pressure in the pump in order to squirt the juice through the injectors I thought. If it's weak then there wont be enough fuel for hard work. Apparently you can restrict the return fuel line to check if it's doing it's job properly. So if you get more fuel after restricting the return then it's the relief valve. All of 17 quid :thumbs

Here's a thought - sorry for the thread hijack! - if we run these trucks on veg the fuel is thicker, and I certainly see a drop off in higher revs when running 100%. Could the relief valve be the issue here as it's 'set' to balance fuel of diesel's viscosity not veggie? All the more reason I need to build my bio plant!

 

[makeitfit]

I think the fuel gets pretty warm pretty quick in that there pump. Once the fuel been to the tank a few times all should be well.

 

[geoffdown]

is that power figure adjusted for transmission losses ?

That fig will be at the wheels and the 125bhp as stock engine will be at flywheel. Car company's like to give u the biggest number so that will be at flywheel :augie so with that I would say there is nothing wrong with u truck.

 

[mjpetersen]

I would be inclined to agree with you, except the map shows a drop off after 3000 and that should not be--it should continue out pretty flat. So the map indicates that it is loosing power when it should not.

Now where that problem is located is the goal of mechanical investigation. Right now it is in the theory stage. It would seem that it lacks fuel. The exhaust did not get real dark with smoke so it would seem that the problem is lack of fuel rather than a lack of air. Therefore the normal culprits that might be involved in fuel starvation--relief valve on the pump, mini filter, fuel filter, or a restriction or leak in the fuel line.

There is a slight leak at the hose connections to the inter-cooler so that is one thing that I will do to keep all the wind in the intake.

Mike