As many owners of classic 911 Turbos (specifically 1978 to 1989 3.3 Turbos, along with 3.3 and 3.6 964 Turbos) will know, these 911’s run on the Porsche ‘Bosch K-Jetronic’ fuel injection system. The is a mechanical fuel injection system that supplies fuel to the engine via a pump, metering head and injectors. Sadly, as time has gone by, we are starting to see an increase in running problems with this ‘K-Jetronic’ fuelling system, along with hot and or cold start issues, all contributing to making ownership more arduous than it should be.  Fear of the car not re-starting after going for a blast, doesn’t make for a fun experience…

A primary reason that these awesome Porsches are starting to suffer these issues is typically down to lack of use. Lack of use means that condensation can build up in the fuelling system, causing metal components to corrode. This then manifests itself in uneven fuel flow to each cylinder, and often corrosion causing blockages within the system. We have evaluated many companies who claim to be able to overhaul or repair this OE equipment, but to no avail. Once the system gets to this stage, it is often past the point of no return. Historically (15/20 years ago) we would have been able to order replacement parts from Porsche to provide a fix, but service items and the system itself are no longer available from Porsche. Fret not, there is a fix that is tried and tested, and we have used for over a decade with many additional benefits – electronic fuel injection (EFI) conversion.

EFI Engine Conversion Close Up

Converting Turbos to run on EFI means changing the mechanical fuelling system to an electronic fuelling system. Our preferred solution being Motec Engine management. This is current generation hard and software that will manage the fuel to your engine at maximum efficiency. Physically, if you open your engine lid, the only aesthetic difference to the naked eye would be that if you peek in behind your intercooler the original Porsche airbox is replaced by a cone air filter. Inside the cabin and everywhere else, all else remains visually the same. So, what is the difference? Essentially the Motec system runs modern fuel injectors to supply fuel to the engine. These injectors are controlled by a modern ECU taking a vast array of measurements. The primary benefit of this is that if your OE ‘K-Jetronic’ system is faulty, this will get your 911 Turbo back on the road, and due to the modern software, the car will then offer far more reliability on hot/cold starts. There is the added option of having a fully mapped ignition system allowing for the removal of the mechanical distributor and CD box.

The flexibility of Motec means that should you wish to run a different exhaust, we can ‘map’ the car correctly to run on your new system – which means a smooth torque and power curve and all-around efficiency. If you decide to start modifying more seriously for big bhp via a bigger turbo or more aggressive cams, all of this can be tuned with greater precision via the Motec ecu. The capability of the modern ECU is quite exciting, meaning you could even opt for different throttle maps for wet/ dry conditions and the installation of a traction control system (with different settings for wet and dry) by utilising the ‘fly by wire’ throttle option for even greater control.

EFI Engine Conversion 930 Turbo

The more modern interface and EFI software we install, allows us to run quicker and more extensive diagnosis on your Porsche, should there be any running issues in future and even the option of remote access diagnosis much like a 2022 992 Turbo S!

So, if you are experiencing any strange running or starting problems with your classic 911 Turbo, feel free to give us a call to see how our engineers are able to assist getting your 911 back into fighting fitness.


To discuss your EFI Conversion, please contact our upgrades team on
+44 (0)1296 663 824 or send us an enquiry online.