Mk2

Covers 89-99 Golf and Jetta, 90-97 Passat, all Cabrios, Corrados, and EuroVans.

KE-Jetronic (or "CIS-E", which means "Continuous Injection System with Electronic control") is a variant on the much more basic Jetronic system. It uses the same ignition controller, but comes with a much more advanced oxygen sensor computer, and sometimes a knock sensor computer as well. It has several wiring variations, depending on the year, model, place of assembly, etc. It was used on various Golfs, Jettas, and GTIs (including 16vs) from 1985-1989. It was replaced by Digifant II on Jettas in late 1987, and Golfs in 1988, but it survived on 16vs until 1989. It had very primitive fault diagnosis (only on cars equipped with a knock sensor). There was no fault memory. Operating theory is a bit more advanced then basic Jetronic. While a vane meter fuel distributor still is used for basic fuel metering, a new Differential pressure Regulator is also used to fine-tune fuel control electronically. Coolant temperature, oxygen content, and basic throttle position (idle or WOT) are all taken into consideration. Knock is taken care of via a specialized controller (GTI/GLI only) that senses knock, engine load, and timing, which is adjusted to eliminate knock. The differential pressure regulator current can be the most telltale test applied to a Jetronic or Motronic vehicle to diagnose it's operating condition (provided everything else is in working order).

Motronic is a much simplified CIS-E system. It is similar to Jetronic in many ways, but also very different. It still uses a mechanical fuel distributor, but has much finer control of the engine. It has integrated knock, ignition, and oxygen sensor control in one control unit. It's coil has a power stage as well. It is also the first CIS system with integrated fault memory and diagnosis. This, coupled with the ability to be fitted with an EGR system, made Motronic suitable for installation in all 50 states (California having the EGR system and OBD fault warning light installed). It was only available on the 2.0 16v. Motronic operates very similarly to Jetronic, except that it is digital, and combines multiple functions into one control head. It takes into account coolant temperature, oxygen content of the exhaust, engine speed, vehicle speed, knock (via 2 sensors), timing, basic throttle position, and EGR temperatures (California only) to control basic fuel metering via the differential pressure regulator, fully control idle air, and adjust timing as well. It also has built-in cold start control (Jetronic relies on an external thermo-time switch and cold start valve). The differential pressure regulator current can be the most telltale test applied to a Jetronic or Motronic vehicle to diagnose it's operating condition (provided everything else is in working order).

Digifant I was developed by Volkswagen to answer growing smog regulations in the state of California (and thus, was only sold there). It had EGR capability, and fault memory and diagnosis built-in. It has a coil with a power stage, and no separate ignition control unit. It has individual control of the injectors (though they are still batch fired), and a throttle potentiometer for full throttle sensing capability, rather then just idle/WOT switches. The G60 version uses a CO potentiometer rather then a Mass Airflow sensor (also a different ECU is used, but the connectors are the same).