2 questions about chips and remaps

[ptkend]

I know these questions must have been asked before, but my search of all forums didn't turn up the exact answers, so can anyone answer these or point me to the right thread.

1. I think my car is stock, but where can I look to check ?

2. Does a chip = more BHP and a remap = more torque, or is it much more complicated than that (or am I just plain wrong) ?

Thanks in advance for your time.

[DaveP]

A chip and remap can be pretty much considered the same thing....

A remap refers to actually changing the code in the ECU - sometimes this is done by exchanging the chip on the board itself.

For your first point, you could open up your ECU and have a look, but even that might not tell you if you are not running standard code...probably the best way to tell is via logging with VAG-COM and comparing your figures with a standard cars figures.

[ZeroK66]

Re-map is commonly used if you have had your standard "Chip" re-writted by a computer (Basically).

Chipping has the same end result... but instead of re-programing the actual chip that is in the car as standard - the chip that is in there is replaced with one that has alraedy been re-programmed.

How to tell your car is standard or not... a boost gauge, a dyno run, VAG-COM as suggested... there are many ways, but they involve bits that you probably dont have right now.

[Dippy]

If you're new to the S4 then the only way you'd know it's chipped will be to do a FATS test (do a search). However finding another owner who has a modded S4 and asking for him/her to test driver would also bring a quick answer.

Adding to the above posts (and sorry if I over-simplify)
The engine is controlled by the ECU (electronic control unit) which is a computer with lots of inputs and outputs. These allow it to read data from sensors (e.g. to measure air pressure, air flow, temperature etc) and control devices (e.g. spark plugs, pressure from turbos, etc). There are a LOT of these sensors and devices, and nearly all are analogue (that is they have many possible values rather than the on/off of digital), and dynamically interact. So there are literally billions of permutations of sensor and actuator values.

Now to make the engine work properly, the ECU needs to control all the actuators properly according to the data it reads from the sensors. It is literally impossible to do this with a conventional program. Therefore the engine designers use n-dimensional maps. These are effectively look-up tables where the ECU matches the data read from the sensors and finds the pre-defined values which it uses to control the actuators.

So the term "remapping" applies to changing the values in these maps to tune the engine.

Whilst remapping is the process of tuning the ECU, the actually method of implementing it can vary. Like any computer, the ECU needs to hold the maps in memory. Since it must not be volatile memory (i.e. the maps must remain if the power is turned off), the maps cannot easily be changed. So they are held in "read-only memory". Such memory comes in the form of electronic devices which were originally called "silicon chips" because the manufacturing process takes thin slices (wafers) from a roll of silicon just like potato chips are made (the ones we call crisps, not the ones the Americans call fries). Because it is read-only, to remap the tuner needs to replace it with a new one containing the new map information.

Hence the act of changing the memory for one with a new map has become known as "chipping".

And since there is f-all point in chipping without remapping first, the two terms have become synonymous.

To your original question, in theory you could ask for a remap for less power and torque. Or maybe just to improve economy. Mapping is all about effort and compromise, and the stock map from the manufacturer is usually a big compromise. The target for most tuners is to increase torque across the rev range without excessive fuel consumption or loss of reliability. Some tuners also try to tune the torque curve to get a big peak power (remember that power is simply a function of torque and revs). This is for marketing only, because most punters just care about peak horsepower without actually knowing what it means.