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Go back to Citroen C1 1.0 12v


There are a number of chiptuning options for the C1. With my other car (Opel Speedster) I didn't have good experiences with chiptuning.

To get more power from an engine you need to get more oxygen into it. The ECU in an natural aspirated engine only controls the amount of fuel added to to oxygen, not the oxygen itself. However, the engine in the C1 has variable valve timing on the intake camshaft (vvti). This allows the ECU to vary the opening time of the intake values. If the control of the vvti has not been optimally programmed (targeted to economy instead of power) there might be a way there to get more oxygen into the engine. By matching the amount of fuel to it there should theoretically be a gain there.

Below is a diagram of the amount of variation the ECU can make on the intake camshaft relative to the exhaust camshaft. The duration of the intake camshaft is 230° and the exhaust camshaft duration is 222°.


To get a fair comparison (just like all the other tuning changes on my other car) I did a before and after measurement of the power. Basically this process is pretty simple. You determine the mass of the vehicle and use a datalogger to register the acceleration of the mass. From this data you can then calculate how much energy was used to accelerate the mass.

So it is important to determine the mass of the vehicle. I use a set of Longacre Racing Vision scales for this. I made a setup on the nice flag garage floor to weigh the C1.



The total weight of the vehicle: 849kg


After weighing I installed my Race Technology DL1 datalogger in the C1with a direct connection to the revcounter signal.


After logging a number of full throttle accelerations in 2nd gear I processed the data in the Analysis software from Race Technology. I set the corrections to compensate for the weather and of course inputted the cars information. Using Analysis I made the following graph of torque and power for the standard car.


The measured values seem to fit nicely. A front wheel drive car usually has something like 15% loss of power between the crankshaft and the wheels. This measurement shows 60hp at the wheels, so adding 15% gives 69hp at the crank. I've repeated the measurements a couple of times and they were consistent.

From Analysis I also got the acceleration times in 2nd gear:

30km/h - 80km/h in 9,23 seconds.

The last thing I did (multiple times) is a to speed test. On the GPS I consistently hit 170km/h (without wind on a flat road).

After much searching, comparing and mailing I eventually ended up with Ziptuning. They've got a lot of information on their website on the C1. The give the following specifications for the car:


They also got a dyno graph ontheir website with the name: dyno_Igo_C1_107_1.0.jpg which indicates it is for the Aygo, C1 and 107 (with interesting spelling). The graph looks as follows:


When examining the graph it looks like there is a significant amount of air being added throughout the rev range, so more fuel can be added and the torque curve is lifted. This confirms the theory about there being margin on the calibration of the vvti system of the engine. Also it shows that the revlimiter is being raised from 6500 rpm to 7000 rpm.

Finally I took a day off and made an appointment on Friday the 4th of September 2009. After about a 2 hours wait the car was ready. After paying I drove home. I didn't notice any change, and after doing all the measurements again I didn't register any difference. Even the revlimiter was still at 6500 rpm.

After calling and mailing a lot I finally got a new appointment on the 2nd of October. I took a half day off, but when arriving the appointment wasn't in the agenda. And they couldn't do anything to fit me in as the hardware wasn't there. So we ended up making a third appointment, this time for Saturday the 17th of October, so I didn't have to take a day off work. The 15th I got a call requesting to move the appointment. Fortunately it could be moved to the 16th, although I had to take half a day off again. After checking the car they said it was now reprogrammed with some adjustments to the pre-injection (I thought only direct injected cars had that?), and everything should be fine.

Coming home I did all the measurements again, but no difference. Again, the revlimiter was also still at 6500 rpm.

After calling again and again, mailing, waiting, trying to give them information on what I found, Ziptuning finally came up with the idea that the wrong software was programmed in the car. My car had been programmed with the software for cars after the facelift (2009), while my car is from 2005. Eventually we made a new appointment for November the 21st in the new building to sort everything out.

Coming home again with the newly programmed car I did another set of performance tests. It was clear there was a difference this time, the revlimiter was at 7000rpm. Unfortunately the rest of the power measurement gave the same values.


Verifying the measurements with the acceleration time of the car also gave me the same value:

30km/h to 80km/h in 9,56 seconds

Lastly, I also tried top speed, but it also still was the same at 170km/h.

Below is a graph of both measurements together. I clearly shows the difference in revlimiter, but no difference in torque.


Another thing which showed up while reading the standard diagnostics information from the ECU. The fuel trims are a lot higher then they used to be. The long term fuel trims I see now are near -16%, while originally they were around 0%.


This indicates that the values in the base fuel table in the ECU have been increased quite a lot. However, the ECU has to correct for this due to the feedback it gets from the lambda sensor to get acceptable exhaust gas quality (for more information on this, see my blog article on chiptuning the z22se).

Of course I sent my findings to Ziptuning. But unfortunately I wasn't very happy with the response they gave me. The final part of their email was (translated to English):

It is good to hear there is a noticeable change.
We wish you much pleasure with the tune.

Again our apologies for the extra time we had to invest.

I'm very disappointed by this reaction from a company which positions itself as a professional tuner.

In summary, you pay EUR 399,00 and take a lot of time off from work plus 2,5 months of agony and you end up with:

  • revlimiter raised by 500 rpm
  • more fuel
But the claimed amount of power and torque are nowhere to be found.