Technical OBD/CHIP tuning diesels. What does it do?

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Technical OBD/CHIP tuning diesels. What does it do?


New member
Aug 3, 2002
Warrington, United Kingdo
There seem to be a number of people offering to increase the power output of your JTD or Multijet engine. How do they increase the power? There are some people selling a "chip box" that plugs in to the fuel rail. I presume this fools the ECU into increasing the fuel rail pressure by interferring with the signal from the pressure sensor. Is it really as simple as that?

One company offer a remapping service for diesels for £310 plus VAT. £355 seems like a lot of money for less than an hour's work. Does this have the same effect as the "chip box" ie increase the fuel pressure? Or do they increase the turbo boost pressure at the same time? What about the injection timing? (Very important on a diesel)

To be perfectly honest, I don't like the way these companies' websites are so vague about what they actually do. Phrases like "the engines parameters are altered for new ones" are used. If they don't want you to know, they should say "we've found a secret way to get more power". I'm an engineer, and I want to know just how much expertese I'm getting for my money!

These questions have probably been asked before, but I'm new to this common rail diesel world.
I suspect, they'll be doing simiar to what is done with petrol engines. When an engine map is written, it needs to take into account the running conditions that the car could face. Crap fuel, crap servicing, extremes of weather etc.
A remap will be optimized for the area it will be used in. Also with a turbo diesel, upping the boost pressure will give more power - and as long as its serviced properly won't have any ill effects.

It is not less than an hours work, as an engineer i'm sure you can appericate the amount of r and d that'd go into something as complex as writing an engine map.
Don't want to start an argument, but the Angel tuning website says this:

"To complete the work takes about 1 hour from start to finish including the pre and post test drives."

At 15 mins per test drive, this means about 30 minutes mapping. I presume they have a standard set of modified maps on their laptop, which they just download when they arrive. So you pay hundreds of pounds for what is effectively a copy of someone else's hard work, including travel expenses. It's not a rolling road session.

I suppose my real question is, how much effort went into producing the engine map? Most of these companies offer maps for up 100 different models. Have they had each car and each engine type on a rolling road for hours developing the map? Or are there a couple of basic principles for getting an extra 30 or more BHP from a turbo diesel that can be applied to all similar engines? I suspect the latter.

I'm not having a go at anyone, £300 for 30+ BHP is cheap tuning. I just want to know if anyone knows how it's done.
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The "hour" is of the customers time, to be available, the tuning can and indeed generally does take a lot longer, usually 2-3 hours depending on the manufacturer. Some cars, like the EDC16's can take 4 hours. Some cars can indeed be done quite quickly, but the average is a lot longer.

Development is done mostly when a new engine type is released or a new ECU type comes out. After that there is much fine tuning to each vehicle type.

All our maps are customised to suit the driver, car, journey type if required, generally though most companies will have something close to the correct balance anyway.

Most companies will loose considerable money on the first half dozen done, then start to claw back costs after that.

The equipment required to tune modern cars is expensive. You are looking at £25k plus to set up correctly. Then on top of that there is travel to the client, insurance, general business overheads, advertising etc. There is also training, other tools, taxes, accountants etc. - you may be an engineer but running a business is totally different, its not just take £300 and make £300 profit, if we make over 10% by the time it gets to the pocket its a bonus!

There are some cars you loose money on, and some you make on quite simply.

Tuning boxes are cheaper as they are simply a bunch of resistors put into a box, cheap components and build costs, but all they do is increase the fuel rail pressure and time the injectors are open for.

ECU remaping, the modern version of chipping, is alteration of sections of the data table used by the engine management program. The usual areas altered are ignition timing, injector opening time, fuel rail pressure, boost, etc. etc. This takes a lot of experience, training and time.

The information on the website is an advertisement of our services, very much like 99% of companies, its not a training manual for engineers.

Rather than ask for opinion on a website, why don't you give us a call and ask us, or another tuning company such as Celtic Tuning, Superchips, Revo etc.
As you are stating that you are an engineer you certainly are aware that there is a lot more involved.

The provider of the Millenium software had to spend about £40,000 in man hours to crack the coding for the Smart ECUs.

Once you start looking into the the cracking of the coding you will feel like station X. All you see is codes once you managed to get into it.

If you managed after many hours to get somewhere you have to start playing with it on the RR, which sets you back at least about 17k. You need a premises and staff etc.

Even if you have cracked the codes and manage to read from it and write to it after you have destroyed quite some stuff you have then to apply the procedure to every car. This is not the end of it. Some of the models (with the same engine) have several programs that are not interchangeable.

This is before any dealer has got the programs in their hands.

Even if it is only about an hours work or if it were only a few seconds. You wouldn't be able to do it for anything near that amount yourself.
Not trying to cause a war here.......but that would suggest that all the tuning companies you see advertising the remaps and power boxes have rolling roads to create the new 'calibrations'. Now I am 99% certain that this is not the case and the reason is - getting more power out of an emission certified diesel engine is VERY EASY - especially common rail.

I'm not going to say who I work for (for confidentiality reasons) however our engine controls group basically detune the engines to meet the NOx emissions for certification. With common rail, much higher injection pressures have allowed a substantial incease to driveability however the engine is still running in a substantially detuned state. Here comes the easy bit.....all the tuning companies need to do is optimise the characteristics that the engine manufacturers detuned and suddenly they are tuning gods!

What the tuning companies basically give you is an engine that no longer meets it's certification (MoT tests are easy to get through as the engine is unloaded). If anyone can prove me otherwise I'll submit your CV to our HR department. On top of that many of the new maps are also taking engine components past their design limits. Do you think that the tuning companies know the design limits for the common rail pump? Probably not but they are still increasing pump pressure. Or do you think they know what the combustion pressures the engine components have been designed around? I'll leave the engineers out there to make their own minds up.....what I can tell you however is that our 2.4JTD is as the original controls group programmed it from the factory and I do have the resource and interface tools to go in and change it.
I do know where you are coming from and agree with most things without making big comments on it.

Before we talk about tuning companies you need to define tuning. If you look at the maxpower version of the definition then I do agree that many of them do not know what they are doing.

Proper tuning companies are going about the tuning in a different way. When I do development work my first call is the factory data. Knowing during my fairly long time in the business many people all over Europe helps things.

Products need development and not just thrown together in good faith everything will go fine. Once developed they need undergo testing. This can't be done to the degree the car manufacturers can due to lack of funding.

Nevertheless a small company like mine is developing goods with the help of a number of specialist in the different fields plus the information we can get from manufacturers. Some of the projects seem to be ratehr small but we still take many months for development and use the best technical help available.

Part of my job involved over the years automotive consultancy, which makes me very aware that the work has got to be very extensive and detailed.

A rolling road facility is essential with the relevant instruments to evaluate the situation and ill development. I agree that a company that does not have a rolling road facility with the other technical aids available as a minimum equipment should be looked at with caution.