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Thierry25 Thierry25 is offline
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Join Date: Feb 2009
Location: FRANCE (Besançon)
Posts: 310
ELECTRONIC CIS fueling & BOOST control


Few peoples here suggested to me to make a thread about my setup. Happy to share my small experience with you…

Just hope you will forgive my French touch English…

Prior to start this thread, I would like to thank Keith ( well-known here as 911ST). Actually he introduced the base of AIC idea to me….He was very patient with me and we exchanged many though by email. From this AIC base, from some thread here, I’ve got some additional idea and I built the following setup.

I own a 964 C2T 3.3 (1991). As many of these car( about 82 k miles), although a good maintenance, the engine suffered of several oil leak. Early this year, I took the decision to make a complete engine rebuild . So I brought my car to my favourite workshop here. (thanks to MJ TECHNIC FRANCE). In fact , as my idea was to lightly upgrade the performance of my car, we didn’t take any risk In order to do the right job and reliable car, we have changed many parts …

During engine rebuild...

In the mean time I sourced a pair of second hand X33 camshafts ( which are SC cams actually). The X33 option is known to increase the power from 320 HP to 355 HP on the stock car. These cams has been installed on my car and timed to 1mm. As the factory did with the X33 option, I polished intake and exhaust ports on each cylinder heads.

X33 ( SC) camshaft

Lastly, the air injection circuitry has been removed and the catalyst exhaust has been replaced by a direct tube. ( followed by a Dansk muffler).

As to the performance improvement, my goal was to keep the original “philosophy” of this car and to get enhanced road/ street performance. So my car is still close to stock version since I kept the original CIS , the headers, K27-7200 turbo , ignition and so on….

I just added the “electronic boost control function and previously mentioned modification to increase the power. In this way and thanks to the community , I knew the CIS limits would have appear quickly if the averaged boost exceed 0.9 bar ( sorry I am not used with the PSI ) .So I knew I should also optimize my CIS to get suitable results. My first idea was to use a separated electronic boost controller and to install a DIGITAL WUR . However, when Keith introduced the AIC Split second to me , when I saw it has 2 channels , I thought it would be very nice to combine 2 devices into a single box , a very affordable and user friendly controller.....

As I wanted to get a safe and reliable tuning, I bought an INNOVATE measurement system. ( data logger + map sensor + wo2 sensor + egt sensor ). (It works very well but I have to complain about the poor customer service…. )

In order to let you know more, here is the diagram of the fuelling and boost controlling system.

Actually the system use an AIC SPLIT SECOND controller. This very affordable controller has 2 injectors outputs with 2 distinct maps ( each output has it map). It also includes a manifold pressure sensor and maps are made according RPM / MAP.


The first channel is connected to a frequency valve ( Andial fueller plumbing) . As known by many here, the purpose of the frequency valve ( with it own map) is to trigger ( PWM / DUTY CYCLE) the so called PRESSURE CONTROL (PC) . In this setup, the WUR is not removed and the frequency valve operate on the PC in parallel.

FREQUENCY VALVE ( taken from ANDIAL KIT / ref BOSCH 0280150945)

The second channel ( with it own map) of the AIC is connected to an AEM boost pressure 3 ways electrical valve. This boost valve is basically plumbed to act on the top pressure of the wastegate. Here also, this electrical valve is supplied with PWM / DUTY CYCLE signal. As there is no PID device inside the controller, the map must be programmed in a special way . However, one advantage of this system is to allow a very friendly RPM mapping ( that’s true that a 250 RPM scale instead of 500 RPM would be helpful for the boost controlling function …anyway, it is a good toy !)

AEM 3 ways electrical boost valve

As you can see on the diagram, there is also an electrical valve between the manifold pressure output and the manifold pressure input of the WUR. In fact I installed this valve in order to allow me to return to original WUR setup. At beginning this was useful to discover the original behaviour of the CIS. ( and to make measurement with the datalogger) Now this valve stay closed all the time …I could simply cut the boost enrichment line but I prefer to keep it wired in case of problem. Unlike the famous adjustable WUR setup, this electrical valve is not triggered by an RPM switch (there is no need)

ELECTRICAL VALVE ( WUR line boost enabling / disabling )
965 C2T / 1991 3.3 TURBO
Old 06-26-2009, 03:35 PM
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