Increasing Performance, Chipping a 24 valve?

[dave stewart]

Has anyone had any experience in chipping a 3 litre V6 24 valve (5058) series 1? Like all previous cars I have had, there are ways and means to improve performance whether it be improving the cylinder flow, increasing fuel delivery/burn or maximising exhaust. In this vein and with other cars that have computer style engine management using a new chip to change these performance parameters seems the go. I was wondering if such an option is available for the big citroen. My car is in perfect condition and the motor/5 speed gearbox is as strong as the day it first was fired up.

[Craigdp]

yep can be done try superchoips of daztec both are good daztec is a little better as it is programed for the car superchips is a programe for the model.

daztec is whats known as a piggy back unit (another ecu with your original)
superchips is just you original reprogramed

daztec gives more performance because its programed to suit the car and not the model.

[noz]

Hi Dave,

From my limited knowledge but some first hand experience you can break the chip mods into 4 categories:

1. The chips located within the engine ecu which do the injection control are replaced with the same chips containing slightly altered programme parameters. The reprogrammed chips are generic to the model and are not car specific. The original chips are 'locked' after they were programmed in the factory to prevent any changes. I believe the 'lock' is burned in and cannot be reversed.
2. The chips located within the engine ecu which do the injection control are replaced with new chips with some basic programming parameters pre-programmed in. A laptop running some software is then plugged into the car and the car taken for a test run under varying conditions (this may also happen on a rolling road). The software on the laptop continually monitors and tunes all parameters dynamically. In this case the final programmed parameters are unique to that car and relate specifically to the engine wear, sticking brakes, tyre diameter etc etc of that car.
3. No chips are replaced at all but a piggy-back device is plugged into the wiring harness between ecu and injection pump. This is the type I know least about so cant really expand on this. The device can be removed when you take the vehicle for a service at the dealers and replaced again when you get home. No-one will ever know. My guess is that it alters the injection timing but I have no proof of that.
4. A simple resistor is added in series with the air temperature sensor and makes the ecu think the engine is cold. It squirts more fuel in as it would if the choke was stuck on. This is the cheapest and nastiest of all the mods (ebay is full of them).

I have first hand experience of mod 1 and 3 above (but not on an XM) but not 2 or 4. In terms of expense they are 4, 3, 1, 2 cheapest to dearest (£20 - £350).

The basis of all of these mods is reasonably simple. The original engine designer aims for an engine of a given power and torque output. However, he can be sure of neither until the first engine prototype is built and put on the test bed. The engine is refined by introducing changes until they are happy with the engine. The engine is then put on a dyno and put through its paces to destruction. Every parameter is analysed and tuned dynamically. Once the performance/longevity envelope is established they then choose the settings which will ultimately reach the market place. To prevent masses of recalls for prematurely failed engines they essentially de-rate the engine to increase its longevity. All these mods are doing is giving you back some of the built in extra which was tuned out for retail sale.

The big question I've never been able to answer is "how much are the chips giving you back?". If you get it all back then it stands to reason the engine won't last 5 minutes. So how much between retail performance and ultimate performance do these chips offer? A friend has run a modified Audi A6 2.5TD (Bosch VP36 injection pump) for the last 5 years with no apparent ill effect. The car does not get thrashed (retired owner) but returns unbelievable fuel economy.

Can anyone else add anything to the technical detail?

Cheers

noz

[jorgy9]

Hi all, that's a very interesting topic.

It surprises me thought that those chips claim to improve economy as well (also Noz cites the example of his friend). All my life I've been listening about extra bhps etc, which makes sense, but now what, do they save petrol as well ??? I thought one of the things those do is they increase the amount of fuel injected, so how can they reduce consumption?

George

[xmexclusive]

Hi George

The chipping increases the torque so that if you drive in the same manner and at the same speeds as previously you will be using less accelerator to get the same result. This will use less fuel hence the economy from chipping. It is possible to chip specifically for economy as well as for performance.
Convincing your insurance company that you have chipped for fuel economy my be rather difficult.
There is also the chance that any one of us might buy a secondhand chipped XM without this being declared.

Regards

XMexc