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D-Jet is electronic, K-Jet is mechanical. Do both have ECU (Electronic Cintril Unit)? If they both have an ECU, what then makes one 'electronic' and the other 'mechanical'?
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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D-Jet was analog electronic. Yes it had an ECU.
K-Jet is mechanical because fuel pressure opens the injectors. There is no ECU.
Only K-Jet cars with the Lambda Sond system had the frequency valve that Phil mentioned. Also this is where the oxygen sensor originated. This is an emissions control system and it has a control unit. But it monitors the fuel/air mixture. It does not control the fuel injection.
Early K-jet cars did not have the Lambda Sond system.
--
'79 242, '84 DL 2 door, '80 DL 2 door, '89 DL Wagon, '15 XC70 T6 AWD
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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I had an early version of a Volvo 245 - a 1975, which had a 240 body and a B20 engine, with the same K-Jet that ran in the 140s. The K-Jet without a Lambda Emissions control system.
The add-on that Phil described - the Lambda Sond Emissions Control, with a CAT as part of the exhaust, came in with the B21 engine.
The first 240s with B21s did not have Lambda systems or CATS. 77-78 I think was the transition to that emission control system.
The K-Jet is, as noted entirely mechanical---and was a welcome replacement to Carburators.
Used in BMW and Porsche... too.
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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I think the 911 Turbo was one of the last cars to use K-Jet, but I'd rather a pair of IDA's on any of the air cooled 911's.
What have you got against carbies on old cars? SU's & Webers all day long please.
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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There’s a fairly concise article on Wikipedia that describes the fundamentals and evolution of the Bosch Jetronic systems https://en.wikipedia.org/wiki/Jetronic
There you’ll also find a reference link to a more detailed writeup on D-Jetronic History and Fundamentals
Google “jetronic images” and you’ll find all kinds of schematics and pics to go along with that. Click/tap on the images to take you to all kinds of interesting sites, some more Volvo specific.
The new fangled D-Jet injection system as used on the Volvo 140E, 164E/ES and 1800E/ES series in the early 1970s quickly gained a reputation for being a bit trouble prone, leaving a few owners I knew pining for their previous SU carbed Amazons. By the time I was ready to trade in my beloved 122S, Volvo had just come out with the first iteration of the purely mechanical K-Jet system (called CIS then) in my shiny new 1974 144GL, an extremely reliable car by comparison to the 1971 and 1972 142E my business acquaintances had that I often got to ride in.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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K-Jet was always called K-Jet, well...K-Jetronic. That was the Bosch name.
No doubt you know CI is for continuous injection. I prefer CI to CIS, using the latter to refer to the constant idle system.
I worked on a D-Jet car once. It was a Volkswagen Type III, the car on which D-Jet was first used. I recall the system had numerous ground points, most of which had been disconnected on this car for some reason. Once I got that all reconnected the car ran great. Not that they weren't a pain in the ass but that's all this one needed.
But I wonder how many people gave up on them because of faulty grounds?
--
'79 242, '84 DL 2 door, '80 DL 2 door, '89 DL Wagon, '15 XC70 T6 AWD
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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It does make you wonder how much of those D-Jetronic issues were things like simple ground faults and how many were failures of the analog electronics. As long as they didn't act up, one of the main selling features for the average owner, especially of the female persuasion, was that you no longer needed to fuss with a choke.
Yes, I should have said CI (Constant Injection) fuel system, not CIS (Constant Idle System).
Just for jokes, I dug out some old 1974 140 brochures I've had buried. They talk about the new and improved "CI fuel system (Continuous Injection)" being introduced into the GL models with no mention of the word "Jetronic", probably preferring to avoid any association with the previous D-Jetronic electronic issues in the E/ES models.
To quote one brochure,
"The GL's two litre fuel injected engine runs on regular grade gasoline. Without carburetors. Without a choke. For '74 a new fuel injection system is introduced. It works on a principle of constant injection. As engine speed increases and more air is inducted, more fuel is injected. It is as simple as that."
1974 was also the year Volvo introduced the big square safety bumpers, the first incarnation of SIPS (Side Impact Protection System), the gas tank more safely positioned above the axle, an electrically heated driver seat and child-proof rear door locks.
Possibly the biggest weakness of the 140 series was rust. Probably the #1 reason you see so few of them these days, far worse than the 240s.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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I had a mild 164 & I am struggling to think of a bug in the D-Jet system. The only 'bug' I can think of is people flooding the things because they didn't RTFM.
K-Jet on a B20E can deliver a lot of fuel for a performance engine, but the runners on both B20E & B30E manifolds are very wrong.
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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“ because they didn't RTFM.”.
Yes, still to this day, many say, “carbs are better”. D Jet runs just fine if it’s maintained and people take the time to RTFM and learn something new, er, different. And they think driving a 50 year old car won’t cost a few dollars?
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi,
I'm not of the 140-160 era or the "D" Motronic system and only can speak of the K-jet and LH Bosch fuel management systems.
This is all called "Evolution."
The K-jet is the more mechanical one over the LH one that came on board in the USA around 1983 with the addition of turbo charging.
The K- jet used the oxygen sensor and a frequency variable, electrical pulse valve, of which, was controlled by an ECU built around the exhaust emissions input signal.
The LH was the further enhancement of the Lambda combustion control system that started, in the USA, around the 1977-78 240 years?
The frequency valve was replaced by, the common thing, for today, called fuel injectors!
The K-jet used pressure and flow injectors, of which, the fuel pressure and air flow, was controlled by temperature dependent mechanisms and mechanical calibrated components.
One has to remember or "realize" that many things were in flux in the Seventies, with the onset of getting better mileage and the rest of the non-Volvo world downsizing. Gas guzzlers or land yachts, as they are called today!
Turbos were brought to the motoring public, to keep those with behemoth sized engines, into car buying!
If they still wanted, to afford or feel their right foot kick their heads back or even to just keep up!
The engines also lasted longer for the average consumer and a bonus was being able to maneuver around the "railroad box cars" to the next traffic light!
This whole affair lead to the non sense of "rice rockets" (motorcycles) and high revving, tire burning circle makers of today's generation!
Things do change and electric is on the way!
The future, looks to bring us some transportation innovations and more mindset changing criteria!
Intelligence and stupidity will always be in a swirl around us, as I guess, it's in our DNA to keep us from getting too bored with each other!
Even Harley Davidison named their first major change in engines an "Evolution" that was designed in cooperation, by Porsche!
Before that, HD use to checked with the Smithsonian Institute to do that!
Now HD has an Electronically Controlled, "Electric powered" Motorcycle.
That is, if you have enough "Change" in your pocket!
$30,000! Complete with uncontrolled options like heating or air conditioning?
Phil
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