Thread: Bosch K-Jetronic fuel injection

depending on where the injector(s) are mounted it works but its very old school...

The last ones I knew of that pulled that were the carby mount type jobs that took the place of the main metering jet.

Obviously it is a pulse system like the old Delco system on the VN comodore then.

If so they are not the most efficient but they are more efficient than a central injected system or even a carbi in most cases.

Im not entirely sure of the workings of them but I know thats the basics of the system.

The better system is the sequential system which is the Ecotech type upgrade in the VS Commondoor and is what is most comon nowdays.

Probably not much help but may be somewhere else to look for some answers.

From the sounds of things it isn't a pulse system.

Wikipedia:

Bosch's K-Jetronic (K for kontinuierlich, German for "continuous") was introduced in 1974. In this system, fuel sprays constantly from the injectors, rather than being pulsed in time with the engine's intake strokes. Gasoline is pumped from the fuel tank to a large control valve called a fuel distributor, which separates the single fuel supply pipe from the tank into smaller pipes, one for each injector. The fuel distributor is mounted atop a control vane through which all intake air must pass, and the system works by varying fuel volume supplied to the injectors based on the angle of the air vane, which in turn is determined by the volume flowrate of air past the vane, and by the control pressure. The control pressure is regulated with a mechanical device called the control pressure regulator (CPR) or the warm-up regulator (WUR). Depending on the model, the CPR may be used to compensate for altitude, full load, and/or a cold engine. On cars equipped with an oxygen sensor, the fuel mixture is adjusted by a device called the frequency valve. The injectors are simple spring-loaded check valves with nozzles; once fuel system pressure becomes high enough to overcome the counterspring, the injectors begin spraying.


So in considering an LPG conversion, would a older style mixer type system be fine?

Originally Posted by B92 8NW

From the sounds of things it isn't a pulse system.

Wikipedia:

Bosch's K-Jetronic (K for kontinuierlich, German for "continuous") was introduced in 1974. In this system, fuel sprays constantly from the injectors, rather than being pulsed in time with the engine's intake strokes. Gasoline is pumped from the fuel tank to a large control valve called a fuel distributor, which separates the single fuel supply pipe from the tank into smaller pipes, one for each injector. The fuel distributor is mounted atop a control vane through which all intake air must pass, and the system works by varying fuel volume supplied to the injectors based on the angle of the air vane, which in turn is determined by the volume flowrate of air past the vane, and by the control pressure. The control pressure is regulated with a mechanical device called the control pressure regulator (CPR) or the warm-up regulator (WUR). Depending on the model, the CPR may be used to compensate for altitude, full load, and/or a cold engine. On cars equipped with an oxygen sensor, the fuel mixture is adjusted by a device called the frequency valve. The injectors are simple spring-loaded check valves with nozzles; once fuel system pressure becomes high enough to overcome the counterspring, the injectors begin spraying.


So in considering an LPG conversion, would a older style mixer type system be fine?

G`day ,

i think you`ll find Rovers use the L type which basically pulse twice for each four stroke cycle or deliver the requied amount of fuel for each cycle in 2 doses .

We have 2 RRs on lpg 84/5 Torque Flite 3spd and 94/5 ZF 4 spd both dual capable , neither use much petrol ever ( never switched ) .
One is 4.0ltr with carbs , other as 3.9ltr hot wire .
The 4.0 has lpg mods the 3.9 has same extractors but nothing else and is longer so heavier both give similar economy on lpg with their different autos .
The ZF behind the 4.0ltr would give much better economy/power as would a manual behind either .

Old school lpg with oxygen sensor/s and therfore it`s own extra computer would be best for EFI cars which still make use of a distributor in my opinion .
Although neither of our lpg cars have this type if i was fitting a system it is the road i`d take .

The point not stressed in all this is that K jetronic is a MECHANICAL injection system, although very late ones had o2 sensor input loop. It does not have a computer.

K Jetronic depends on the depression of a plate to control the volume of fuel injected, hence the big round thing with tubes out of it.
There is no reason other than wear that it should not be economical , but they depend on the engine specs being exactly as designed for.
main problem areas are wear in the injectors (which have a spring like diesel injectors) and wear in the metering unit, which is quite expensive to fix and hard to find anyone who knows.

L Jetronic (Bosch flapper) is the parent of the ELECTRONIC system on the early Rangies, and LE Jetronic ( MAF sensor)is fitted to 3.9.
All are continuous injection.
Ther eis no reason that ciontinuous injection should be less economical than sequential, as over about 1500RPM sequential injection is spraying on closed valves some/most of the time anyway.
For a discussion refer to the Megasquirt site.
Regards Philip A
PS because there are few people not that can adjust K Jetronic, many people fit aftermarket electronic when they have a problem, as a full aftermarket system and tuning may be cheaper than a new fuel distributor.

Originally Posted by B92 8NW

foreword: I know nothing about fuel injection on petrol engines having only owned two diesel Land Rovers.

Needless to say I've been looking at a few vehicles equipped with Bosch K-jetronic injection. I'd have assumed that a fuel injected engine would only inject fuel on the intake stroke but someone has told me that K-jetronic systems spray fuel continuously the minute the engine is started.

I'd have thought that this would waste craploads of fuel - or have I missed something here?

Check this site here. http://www.diagnostic-assistance.co.uk/mech_inj.htm

Also, Google "K-Jetronic" and you will bring up a few links.

This was used on a lot of early Jags AFAIR amongst other Euro brands.