Frequently Asked Questions

Q. I have a chip fitted. This has improved the Torque but I still need to know if I can tow in overdrive or not. I tow a 2,300kg caravan behind a Nissan Patrol 3 ltr.

A. Manufacturers generally recommend ‘no towing in overdrive’. This recommendation would be based on the fact that the ‘overdrive’ gear ratio is usually not ‘as strong’ as the other gear ratios. Gears such as 1st, 2nd, 3rd, and 4th would be ‘magnifying’ the engine output to the wheels and be at slower road speeds and would have a ‘gear ratio’ looking something like 2.68:1. Very simply speaking, this example would mean for every 2.68 turns of the engine the wheels would turn only once or 100NM engine torque magnified to 268NM at the wheels.‘Overdrive’ ratio would ‘reduce’ the engine output to the wheels BUT this offset would mean higher ‘cruising’ road speeds at less engine RPM and would have a ‘gear ratio’ looking something like 0.92:1.

Very simply speaking, this example would mean for every 0.92 turns (less than one turn) of the engine the wheels would turn once or 100NM engine torque would now only be 92Nm at the wheels. Somewhere in the ‘overdrive’ equation 8NM of torque has ‘disappeared’ and it had ‘disappeared’ in the form of ‘absorbed mechanical effort and heat’ within the overdrive gear. Running then for extended ‘full throttle/heavy load’ times in this ‘overdrive’ gear could mean a build-up of extra heat in the gearbox which could eventually cause some sort of gearbox issue after time.  So...we agree with the manufacturers on their ‘NO TOWING’ recommendation also BUT remember that manufacturers policies are based on ‘blanket policies’ covering the ‘worst case scenario’.

In the ‘real world’ common sense should be used and if you are towing but on a ‘flat road’ with light throttle it could be classified as ‘safe’ in that particular condition to tow in ‘overdrive’. If you start finding though that your ‘foot goes down’ on the throttle for some time due to mountains of heavy winds then it would be ‘common sense’ to change out of ‘overdrive’.‘Automatic gearboxes’ and ‘towing in overdrive’ is usually a more simple task because ‘electronic controls’ are watching engine torque, throttle position, gearbox temperature etc. and  will pretty much watch everything and select the right gear, when needed, for you. In fact even if you are towing ‘safely’ but the load is too much for the gearbox warning light will eventually tell you if you have problems coming. So in summary use common sense when towing loads and if in doubt, stick to the manufacturers recommendations.

Q. On your website you state the output of the standard 5LE engine as 40kW but in the sales brochure for that vehicle the output is given as 71Kw, which one is correct? Why is there a difference between the quoted figures and the dyno figures?

Q. DPF (Diesel Particulate Filter) problems. I’ve heard that this new ‘add-on’ pollution control device is having problems and blocking up even with a stock standard vehicle. Will the DPChip make my vehicle's DPF filter block up?

A: Just to name only a few vehicles. Mitsubishi Pajero 3.2 common rail diesel automatics and late 2007 onwards Nissan 2.5 CRDs equipped with DPFs are certainly having their share of problems with blocking DPF filers in 'standard' form. The brains at DPChip have been in the Diesel industry for a very long time and have seen all the ‘craziest add-ons’ come along and luckily eventually go but we would have to call DPF technology the ‘craziest idea’ from manufacturers yet!There are 'BIG' problems with the DPF technology on a standard vehicle generally and our opinion is that it has less environmental benefits than is worth the headache.

The problem is that the 'idea' on paper (and maybe in a CAD design program in a designers office) seems OK but DPFs are very prone to blocking up from not coming up to 'cleaning' temperature enough and also the DPF is additionally hindered by sooty diesel and maybe other fuel related issues. Change injection timing and fuel control and it may further increase this problem.Another common thing associated with a vehicle having DPF technology on is that the fuel consumption is higher than normal. For example we regularly have customers call us asking why their new ‘same as the last vehcile’ 2008 model get worse than the last 2006 model they had? Thanks to DPF technology and the ‘every working’ cleaning cycle associated with it, the newer vehicle will use more fuel as it constantly tries to ‘heat up and clean’ the DPF filter.I'm not sure if you understand how a DPF filter works but in case you don’t it's like this:

Diesel Particulate filters (DPF) catch microscopic bits of soot that have not been eliminated by the Catalytic convertor. As with any filter (think of the bag in your vacuum cleaner) they have to be emptied regularly to maintain performance. For a DPF this process is called 'regeneration' – the accumulated soot is burnt off at high temperature to leave only a tiny ash residue. Regeneration may be either passive or active.Passive regeneration (cleaning) takes place automatically generally on highway-type runs when the exhaust temperature is high. Many cars don't get this sort of use though so manufacturers have to design-in 'active' regeneration (cleaning) cycles where the engine management computer (ECU) takes control of the process.

Active regeneration takes place when the soot loading in the filter reaches a set limit (about 45% which really isn't much) the ECU will make adjustments to the fuel injection timing or volume to increase the exhaust temperature and initiate regeneration. If the vehicle is equipped with an 'inlet shutter valve' this will also be closed to reduce air volume and assist with raising exhaust gas temperature in a ‘bid’ to ‘burn up’ the soot build-up in the DPF. If the journey's a bit stop/start the regeneration may not complete and the warning light will eventually illuminate to show that the DPF is partially blocked.  The condition of the DPF is measured by 2 atmospheric sensors in the exhaust system. One before and one after the DPF. The difference in exhaust gas pressure between these two sensors is used to determine how ‘blocked’ the DPF is (the more blocked the DPF the higher the exhaust pressure will be at the sensor before the DPF). It should be possible to start a complete regeneration and clear the warning light simply by driving for 10 minutes or so at speeds greater than 80km/h.If you ignore the light and keep driving in a relatively slow, stop/start pattern soot loading will continue to build up until around 75% when you can expect to see other dashboard warning lights illuminate too. At this point driving at speed alone will not be sufficient and the car will have to go to a dealer for ‘forced’ regeneration (cleaning) or even possible replacement of the DPF. This ‘forced’ cleaning can be quite traumatic to the engine and generally will require engine oil replacement!

If warnings are still ignored and soot loading continues to increase then the most likely outcome will be a new DPF costing around $2000.The most common type of DPF features an integrated oxidising catalytic converter and is located very close to the engine where exhaust gases will still be relatively hot so that passive regeneration is possible. There's not always space close to the engine though so some manufacturers use a different type of DPF which relies on a fuel additives to raise the ignition temperature of the soot particles so that the DPF can be located further from the engine. The additive is stored in a separate tank and is automatically mixed with the fuel whenever you fill up.With this type of DPF regeneration will be initiated by the ECU every 400km or so depending on vehicle use and will take 5 to 10 minutes to complete. You shouldn't notice anything other than perhaps a puff of white smoke from the exhaust when the process is completed.

So...that’s it in a ‘Perfect World’ but we all know the World ‘isn’t perfect! Usually the reason behind a vehicle bringing 'on' the DPF warning light may be the driving style/conditions remembering that this massively influences the 'cleaning now due' condition of the DPF. We have many DPChip systems running in DPF equipped engines and we have had only some that bring on the DPF warning 'light' and many that don't. Of the ones that have, the smart owners have had the DPF removed, the 'atmospheric' sensors re-installed in the pipe and have never had a problem again. The catalytic converter has not been 'touched' in these instances as we have never seen catalytic converter problems. It's not a requirement of most countries outside the EU laws yet to have a DPF and hopefully before it does become law to have, that technology is 'thrown in the bin'. Being Diesel Engineers by trade we hope the 'so called' manufacturers engineers come up with a much more sustainable/common sense approach to reducing 'ultra fine' diesel particles. We hope this answer helps you make an informed decision on the matter. Remembering that we have a 30 money back guarantee so there is really no risk to you at all..

If you have any questions that are not answered here please contact us.