@@anthonidanowski9404 Shovel you shaming Comment up your Ass Buddy.... i studied this System over the Years, own all Technical Manuals and even Stuff from Bosch YOU would not even get your Hands on. Also Tools to fine tune that System. And even had Contact to a Guy who worked at BOSCH during the Invention of the System - his Comment: "the biggest POS we ever made...." Quote End. I learned plenty of Stuff from him. But in the End it´s an old, obsolete System full of Flaws. Yeah, mine runs perfect, but that does not make it more Lovable. Mine never had any Issue after i was done with my Cars fulll Restoration.... but that doesn´t make the System better. It´s just crap ! Yes, for it´s time it was "ahead", but pretty fast obsolete. That shows that it was just a kind of Learning Step in between to a better System.... KE and Digifant for Example. IF the K-Jet was so magificent, why don´t we still use it?
CIS is an engineering marvel of a time before EFI, don't forget that this was the best in the world injection solution at one point in time, my hat is off to BOSH for giving me such a magnificent system..
It's actually a really simple system. Testing the different components is easy. To anyone who has this on their car and wants to know exactly how to tune it and see whats going on, put a wideband O2 sensor in your car with an AFR gauge. Every time I do this, my cars run silky smooth.
It's the same thing on any car with any fuel system. drill and weld an O2 sensor bung into the exhaust at an acceptable angle. Add the wideband sensor and route your wires to the interior. connect your wideband gauge and monitor your AFR under all driving conditions. Be sure not to adjust anything when the engine is still in its warm up phase, IE, get the car to normal operating temp.@@nboy7
Had a problem in my Porsche 924 equipped with K-Jetronic years ago. It would start fine when cold, but crank and crank when warm. Turns out, I had a split in the air induction boot that was allowing air to bypass the plate so once it cooled down, the cold-start circuitry would kick-in and it would start fine. Replacing the boot made it all work wonderfully. This system is SO intuitive!
I'm a lucky person. Had my '91 MB M103 CIS-E system adjusted by a good tech in 1997. That was the last time anyone has ever touched it. I do routine maint. often - use good gas and do sufficient highway driving in order to keep clean gas flowing thru the system. I have read 100s of stories about people having trouble with their CIS system. Many are DIY types who buy all of the special tools needed to adjust its various components. Its my belief that in some cases, these DIY types have no clue what they are doing when they start to tinker.
This system is very reliable and I think you are right that people who have no idea what they are doing actually cause more harm when they start to tinker with the system. Rarely the fault is with the K-Jetronic itself. More like with vacuum leaks, leaking injectors etc.
I was given a '76 Audi Fox years ago. The car had been sitting unused for many years and needed some work to get it road worthy. I quickly had to learn this injection system. Once I had it all figured out, it was pretty reliable! And this was in the days before RU-vid and Google. All I had was a Haynes manual, and fortunately a nearby foreign car parts store run by an old German gentleman who used to work on Audis, VWs, Porsches etc...
Worked on a lot of these in Volkswagen cars in the '70's and 80's and a few early '80s Volvos. Cold and warm start issues were the most common thing I remember working on. If you could get them to start they ran pretty well. Drippy start injectors, bad cold start times and leaky check valves made life... lets just say interesting lol. I much more prefer the LH-Jetronic systems used on the Volvo 240's. The LH 2.4 was bullet proof!! Thanks for the flashback!
Hello Tony, Im having a problem with mu jetronic. It starts really bad when the engine is cold. Like really heavy. When it starts is stutters for like 10 secs and after that everything is fine. Do you have any ideas what might cause that problem. I have checked the spark plugs, injector leaks, changed the fuel-head (the one with airsensor hand), lambda, and fuel pump. Im out of ideas :( Have a good day!
K-jet is a much simpler system than EFI. However, EFI is much easier to diagnose. People hate it because they don't know, or don't want to diagnose it. With EFI, just a simple computer scan will point you in the right direction. K-jet was from the time of real mechanics. Back when you had to adjust valves, adjust points, adjust fuel system pressures, etc. Unfortunately with modern technology, everyone either has a husband or dad that is a so called "mechanic" just because they have a scan tool and some sockets. My hat is off to Bosch for this great fuel system. When tuned correctly it can support good power, the acceleration and response is amazing, the sound is unique. And it blows people's mind when they see the mess of fuel lines an hoses under the hood.
Yes, this is a really good point. I had a Chevy OBD0 TBI that I bought cheap. It ran okay at some points but crazy elsewhere in the range. The light was on. All the older mechanics that knew more about a short block than I will ever dream of were scared of it. I jumpered it and it flashed out some codes. It was getting false air and maybe a bad TPS or IAC. Something else, too, but can't remember. It only took $75 and a few hours to make it purr. So, yes, self-diagnostic can't be beat.
Big clue to lean running when they inform about gauze filter in tank. Caught me out with my 86 audi. The gauze clogs with rust and starves the pump. Look after your cars folks 😀
What cool 1970's video, I remember these kind of video's a school This was very informative and clear on how the K-Jetronic system works, wll come in very hand on my 1982 982
Brilliant explanation video. Well done for posting. Anyone with running issues should take notes - this vid could save you money and time. Check the basics first.
Thanks, I'll have to pick that up. I don't know if you have read this book, "Bosch Automotive Electric-Electronic Systems" but it really helped me understand FI as seen from Bosch's viewpoint. Obviously, K-Jetronic is completely outdated, but studying it really helped me understand. EFI systems have such a low part count that a beginner is left in doubt as to how it does what. With the old mechanical, every function has a part that corresponds to it. That book explains better than this vid.
I have this system in my Mercedes 380SE. It's so complicated that I'm scared to mess with anything on it. I always have to give it gas when I start it in the morning because of the stupid warm-up valve. Plus my exaust smells like pure gasoline.
Tom Butchen OK then how long would it take you to explain all the components and function of an EFI system in comparison? If you don't understand k-jet do you understand efi? CIS is more intuitivly understood than EFI IMO..
Ed Leclair I agree with you now. When I first commented, I didn't even know what a camshaft was. I did some work on my EuroVan with a VR6 and with so many sensors and computers for the EFI alone, it makes K-jet seem so simple. You can actually see every part working, instead of messing around with digital components. Yeah, it's less efficient than EFI, but would you give up simplicity for efficency? I sure wouldn't. My K-jet is still going hard, so much so that I blew my head gasket and I'm pulling the system apart now. K-jet only seems overly-complex for narrow-minded people who are too lazy to figure out the problem.
Why does my 87 have K jet but my 82 has L Jet? I'm almost certain my WUR is bad, it rattles. Makes me think I've got low pressure and it's just flowing back to the tank.
The Bronco I had with the speed-density type fuel injection never left me stranded...and what did go wrong with it was never a result of EFI failure...not saying it cant happen, or hasn't..but it never was for me. I wouldn't go to an audi if i was looking for reliability though. Mine had so many electrical issues that its a good thing the fuel injection was mechanical, or else it wouldnt have even drove.
I don't know if I would go so far as to say that TBI>CIS... especially since around '91, you would have had CIS-E, which would have had O2 sensor feedback, and also CIS is port injection.
trying to figure out why the injectors are spraying too much fuel into the cylinders. i think its because the plunger, thats controlled by the air flow meter, is stuck open causing it to send too much pressure to the injectors. im not sure if it is attached to the meter arm or if its pressed down with a spring, the video didnt mension either.
i am changing my bosch k-jetronic fuel injection of my passat variant cl to carburator Webber, anybody know if the admision is the same of audi AP1.6? thanks
I would honestly hate to work on a broken Jetronic ...I think all I would be able to do is take it apart, clean it, and put it back together and hope it works. EFI always seemed to make things easy (Even OBD-1, which you can also pull codes on just like the current OBD-II, even on the vehicles without the check engine light)....Most of the time its, pull codes, okay this sensor went bad, replace sensor, car runs like new. If not, you are at-least pointed in the right direction
the video says' all injectors spray fuel at the same time continuously'. what happen to the fuel sprayed into cylinders that are not at its compression cycle (or ignition)
Hi Vilhuer, do you know a skill mechanic who knows to service the KJ tronic of my Volvo 740 turbo ? B19ET is the engine and the car has been made in Sweden in 1984
If you have a choice to avoid E10 petrol, do so. It is the devil for all older fuel systems that are not specifically set up for it. I don't imagine K-jet being any happier with E10
No computer, absolute air density sensing! At the mechanical tolerances we can machine to these days, I would like to see a non-computerized mechanically analog car built that the CIA can't screw with and use your own car to kill you.
Nah, my bronco ii had muiltport fuelinjection, 100% electronic. The only thing was that it ran from a MAP sensor instead of a mass air flow like vehicles that shortly followed it. Hell, in 1991, the Ford 4.0 had the mass airflow sensor and already has distributor less ignition. Im surprised audi was still using this ancient setup in 1991.
We were all victims of this terrible, mechanicle, unrealiable, fuel gazzling bosch shittronic system. Looking back at it now, it brings back memories though.
My old audi had this bullcrap. It is literally mechanical fuel injection. Crazy concept for a petrol powered car...especially since my audi was a 1991 and had mechanical fuel injection, yet my other vehicle, and 1987ford bronco II had electronic fuel injection. Which is obviously better and more sophisticated
I have a Merc 123 estate quietly rotting away in the yard. Every six months or so I amaze my friends by putting a battery on the car and it fires first time every time. If it wasn't so rusty I'd trust it to take me anywhere. Mot testers have no soul.
Jerking your chain a little there, man. I just have to take up for Bosch. I shade-treed on old Mercedes when I was a teen and love all things Bosch. Never had any trouble with Ford EFI, but it always worried me, whereas with the MB, I knew I had carburetor-style reliability with FI precision.
for my w116 mercedes a change the original part accumulator bischoff 1164700516 for this new part 1264700116 for a good start when the engine is hot ! bye !
I horrible moment in automobile history I hate this system the price for a fuel distrbutor can cost 1,000$ PLUS for new and rebuilt ones are disaster waiting to hapen
Stay away from ethanol fuel, stick to as pure gas as possible add an additional filter to the fuel distributor inlet down to a few microns I think 5 or 6. Your system will be worry free. Ethanol eats the seals up and particulate matters clogs the micron size slots where fuel goes through. Never let vanish build up in your system, store your vehicle with fuel tanks of pure gas. Long term Headaches solved.
Thanks this shitty BOSCH invention i have problems with cold start. I have been to lots of electricans, mechanics, even audi center. Anyone doesnt know whats the problem. Nice job BOSCH
most likely your fuel filter is clogged -if you struggle to blow though it its clogged . If the car has been left for a few years the warm up regulator (the boxy thing with two fuel hoses and electric connection) is clogged up .Take it out when cold, clean with carby cleaner and blow it out . It must be cold or you won't be able to blow through it .It's basically a choke system - cuts off when hot . The K-jet system is pressure sensitive so anything that stops the pressure getting up to spec can cause problems. The injectors are really sprayers! very little moving parts . Hope this helps.
There is nothing wrong with this system. At the time it was a major advancement over carburetors. Even now I consider it superior to carbs. The system is shitty though if its not maintained properly, and taking it to skilled mechanics/VAG specialists who aren't 100% skilled and confident in CIS is just throwing money away. In most cases VW/Porsche enthusiasts who toil endlessly on these systems are a better bet than current VAG mechanics, as they know the troubleshooting better, and also how to deal with the scarcity of spare parts.
Most techs these days will have no idea how to work on or diagnose CIS, they are not trained in old systems like this. You need to take it to an old timer who worked on these cars when they were new.
Both of Ford's systems (speed-density and mass-air) from the 80s and 90s are inferior to Bosch, which had Motronic and coil packs out back in the 70s. Even the mass-air Ford system squirts fuel on one bank of the V8 then the other. This approach is virtually a continuous squirt. Furthermore, if anything screws up, you are on the side of the road with your thumb up your butt. K-Jetronic is deliberately mechanical for those of us who have owned F-series Fords and want D8-dozer type reliability
K-Jet fanboys: "K-Jet is the best, so reliable. So tunable." People who actually know about engines: "Yeah? Now go do a turbo conversion with it." K-Jet fanboys: "Ah, well. Umm..."
Japanese were smart. They made the best vehicles without using this SHIT made by Bosch. Sorry but at that time Japanese were using a good old reliable carburetor.
