General Cable tuning

[SamBowcock]

Lo all,

Just looked at the German ebay concerning these cable add-ons that are supposed to give the jtd engines 20% more ps anyone have experience wit these?

FIAT Diesel JTD* ASA CR Tuning Box * +25%PS + 30%NM

http://cgi.ebay.de/FIAT-Diesel-JTD-...057657752QQcategoryZ72652QQrdZ1QQcmdZViewItem

That's the site if anyone is interested.

 

[polecat]

Ignore them. Do a site search for resistor for more info.

 

[Hellcat]

Can't get the link to open. If it's cheap then it will be just a resistor which tricks the engine into thinking its running cold. It therefore overfuels giving higher power, but poor mpg and potential damage.

 

[RS Pilot]

I had one on a diesel Freelander (not common rail, this was Bosch rotary) - it made a huge difference. These are not the air flow meter resistors referred to above. The one I had was adjustable through 3 potentiometers so you could control the black smoke under acceleration.

My recommendations for common rail (JTD) would be:-

1) If the main principle is increased fuel pressure leave well alone.

2) If you do go ahead, keep an eye on the boost pressure so you don't go over the top on the cylinder pressures. I have a friend who worked for Powertrain (went bust with MG Rover) and he let me know the max limits for the Freelander L series engine so I kept within them. If the company selling doesn't know these limits for your engine then be concerned.

There are obviously remaps for the JTD - the recommendations read the same for those too.

It is very easy to get more power out of modern diesels however the power comes at a cost and this is usually engine / transmission life and reliability.

 

[Marea147]

The variable resistor types, or the plug into the harness types normally work on areas such as the Fuel rail pressure sensor. Simply reducing the output from this will force the ECU to increase the pump pressure.
With a higher fuel pressue and the same injector opening time, you can increase the fueling. Go too far and you get black smoke, but you will get more power. This works quite well on Bosch EDC15, but EDC16 requires more sophisticated methods....
You can get a lot more power and torque though!!!!

What it does for bore wash or injector wear is probably irrelevant over 3 years/60K miles, but will shorten the life of the engine in the end....

There are several other methods as well, but in the end (assuming no actual physical engine mods) they all cause shorter engine lives, through higher cylinder pressures. The question is how short, and will you still be the one driving it when the bell tolls????

 

[polecat]

Just looked into this and it is a common rail pressure sensor resistor. It will permanently overfuel the engine.
You can get a fuel pressure regulator for about that price and do the job properly.

Example here http://www.fuelsystem.co.uk/pbv.htm not sure if they do a diesel version though.

 

[Marea147]

Or you can get a few variable resistors for pennies, splice them into the harness connector to the rail pressure sensor, and go twiddle until you just get smoke under load..... Yeee haaa.
This should work well for all older JTD engined cars (not MJTD, as this has a more sophisticated control system)

Cowboy tuning at it's best!!!!!!, but then that is pretty much what some of the "tuning" devices are anyway underneath the nice plastic boxes that they sell.....

Of course there are now more "professional" services on offer, such as re-flashing the ECU. Basically all they are doing is increasing fuel and boost levels to get more torque.

In some instances, i.e when it involves bypassing an emmisions device, or emisions limitation, such as in lower load areas, where you can get "free" fuel economy increases without necessarily causing potential engine damage, at the expense of the environment, however aside from this there is normally no such thing as "manufacturer slack", to account for engine to engine tolerances etc. in the full load regions. The limits are there for a reason, such as engine durability.

Still, as I said before it is fairly easy to get more power and torque, and if you only want to run the car for a few years before you sell it on to some poor unsuspecting soul, then go for it, as it is unlikely to go bang that quickly, and you probably don't drive full load very often anyway.....