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FAO Capt Slarty


In some post you mentioned that you have information about the Renault Renix ECU. If it isnt too much trouble, could you please mail me it? As Ive been looking for info from everywhere, but have found nothing useable really...



Ok, I thought that if you had some files about it in computer which would be easy to send, but if it is on paper or in your head its bit more difficult
I would like to know about its working principle and about that diagnostics socket. Fastchip ( sell this info display which connects to diagnostics socket, and with that you can see all the variables which are used by ECU.
So I thought if I could make similar device myself. But then I should know more about the socket and which pin gives which information.
With some microprocessor it shouldnt be too difficult.

Hi Sir.. that is an intersting page.. I dont see any 172 info though as the ecu is very different from the 16v units.

I am not familiar with the 16v ecu, just the 172, and that is limited..

All I know at the mo is that the rom can be read by an eprom reader / programmer.

programming by the diagnostic port is possible but limited.

changing more than a certain percentage of bytes in the map will caus ethe ecu to fail due to a checksum failure (and the checksum is calculated at various points in the eprom / flash..

it would seem impossible to supply a chip for another unit.. you would HAVE to copy the actual chip in the actual ecu due to it being encoded with the key transponder for security.

I also have no info for the diag output or input yet for the 172...

Due to the security on the ecu, it would be a nightmare to program.. but no doubt someone may find a way around this eventually.

  Corsa 1.3 CDTI

OK sorry to sound a bit thick but on cars like the Audi S3 etc how comes if you just chip it you get an extra 30bhp or more ?

I cant see but adjusting and spark timing etc that it is going to make that much of a difference. What else does the chip do ?

What do superchips do to the 172 to add an additional 5bhp or so ?


ClioSport Club Member
  E90 LCI 330d

ChavyBoy -

That is because the S3 is a turbocharged engine and as such it is very easy to get more power and torque by simply "chipping" the ECU.

All the chip does in the case of a turbo car is allow more turbo boost and also adjusts the fuelling & igntition to match the new levels of boost.


Hi Chavvy.. no probs dood...

on a turbo car ie A3 t... then it is simply a change to the boost level and boost level cut off..

allowing a small increase in rpm can allow the boost to spiral up too. so 30 bhp is simple.. (but, the owner could do it himslef in a cruder way for 2 quid !!!! (with a brass tee piece, plumbers solder and a fine set of drills )

superchips can alter a limited amount of positions in the ecu fueling map and ignition map. These can overide the manufacturers data and richen up the mixture mid range and top given a small increase in power but hardly, if at all, noticable.

Manufacturers lean out the mixture on cruise and part throttle for both economy and emissions.. so you will lose economy slightly and emissions may increase.. all in all not really worth it on a N/a car.

  Corsa 1.3 CDTI

Ahh cheers now I know. Another question how is the boost controlled because you are trying to change something electronically that is a mechanical piece ? Does this make sense ?

No probs Koivis..


controlling the boost on a mechanical actualtor by electronic means is actually quite simple.

heres how it works.

if you can imagine a simple pipe from the compressor outlet (Boosted air pressure) connected to the wastegate valve.. then at a given pressure the wastegate will open allowing exhaust to bypass the turbo drive impeller. yep ?

this will hold a specific pressure and reach it as quickly as possible.

now.. if we introduce an electronically controled valve IN that pipe.. we can close the valve to stop the wastegate actualting - ie - it doesnt see the pressure..

to make it all work properly.. heres what we do.

the valve to use is a PWM solenoid.. PWM = pulse width modulated - basically you can turn it on and off rapidly and also control the mark to space ration - ie the period ON TIME to the period OFF TIME.. this allows you to control how much pressure the waste gate sees at any given time by varying the flow of compressed (boosted) air to the wastegate..

now what ya need to do is change the wastegate assembly or alter the spring internally so that the wastegate is operating at a lower pressure - ie - comes in earlier.. you now use the valve and pwm circuit to raise the actuation pressure to the desired level.. now you have control over the ramp up time - ie, you are not waiting for the preset 6-10 psi to come in. and the abrupt delivery of power, you can effectively cut boost at, say 3 psi, then allow it to build up in a controlled manner in any way you require.

Hope that helps.. the best ideas are the simplest LOL..

  Corsa 1.3 CDTI

Simple, so the mechanical part is then almost replaced by the electro mechanical part... I see simple yet effective.

well, yes, sort of.. the mechanical part is still there... just that you can trick the wastegate into seeing different pressures (always below - never above waht is available)

the lowering of the actuation pressure of the wastegate is the trick most often bypassed or missed by turbo add on manufacturers (as well as air temp control !)

By lowering the actuation pressure of the wastegate you have contrl over the ramp up time as said above.. this allows you to bring the turbo in progressively, and also then to allow any boost level you require.. up to TNB