D-Jet write-up?

xing6666

xing6666

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I've done a Google search on this and come up with some sites that generically overview the Bosch D-Jet, more specifically on Mercedes, but I'm wondering if anyone has a comprehensive write-up specifically oriented to the D-Jet setup on the e9 CSi's. As the metalwork begins on my car, I would like to use the time to brush up on the technical aspects of this car that differ from my e24 and this is one of those areas. Thanks in advance.
 
THe D-Jet in the e9 and in the contemporary Mercs, Volvo (1800) and Volkswagens are more or less the same. Even betweeen 4,6 and 8 Cylinders. The FI in most any Jaguar V12 is basically the same thing as well, even when it´s labeled Lucas. A writeup of any will tell you most things you need to know.

Other than that the blue books will give you even more, including set-up and dignostic procedures and data specifically for the E9.

There also once was a book by a Mr. Roger Bywater (a Jaguar development engineer) on fuel injection that covered fuel injection and particularly the D-Jet very well. I don´t know if it´s still available anywhere.

Also, the D-Jet is a pretty simple (and mostly reliable) thing. The only thing prone to failure is the pressure sensor and the pickup in the dizzy. Other than that, it´s pretty much bullet proof (of course you need to make sure the fuel lines are fresh, all gaskets are in order, the TPS is working etc. but that´s just standard FI maintenance)
 
True story about Dinosaur-Jet.
After the car being stored for about 30 years I put the 12V back to the original ECU.
I was prepared this box could/would become a roaster and in advanced I got a set of carbs as a backup for the coming "on the road again".
What happened after a few seconds to filling the fuel lines the original (renovated) csi engine started up like nothing!
I had my garage door closed because I didn't think it would start!
First of all I open the garage doors and wondering what happened.
Since that day the D-jet never ever let me down.

Ain't that a love story? :-)
 
Well I'm about to do the same. My car has been sitting for close to 30 years. This week I replaced all the fuel lines and injector rubbers, pump mounts etc tested them, reinstalled. Within a day or two ill be ready to attempt to fire it up. I'll let you know.
 
The D-Jet has the advantage of having no ram, no rom, no bios, no Firmware, no OS, no battery to hold memory, not aven a single IC.
Only discrete transistors, resistors, capacitors. All from a time when those were built to last and then properly soldered onto a really fine circuit board by pros.
So why were you surprised?
The only things in D-Jet that can fail are the pressure sensor, the Throttle Position sensor and the trigger unit.
But do go ahead and change the fuel lines, please. Would be a shame if the car fires up just fine and then burns down a little later...
 
Brendan said:
http://www.amazon.com/Bosch-Fuel-In...11746620&sr=8-1&keywords=bosch+fuel+injection

I have this one and it's very good, covering all Bosch models. Huge help getting my K-jet 924 running.
Click to expand...

Fantastic, I'm going to purchase this book - thanks for the pointer.

The car is actually already running fine. It had been sitting for quite some time and was given a new battery and some new gas and fired right up. My desire to know about the system is purely as a matter of understanding a system that I am not familiar with. I understand it is not that difficult to understand but they can be finicky when it comes to vacuum issues.

In regards to vacuum - has anyone changed to a Schrick cam? The next question you are going to ask is: "which one?" This I do not know - which I understand is an important detail. Apparently this car had "one" installed and as far as I could tell, it ran alright. I had a discussion with Jime Rowe of metric mechanic and his personal experience is that higher overlap cams do not work well with D-jet systems, precisely due to the fact that more overlap leads to lower crank case pressures than would be found with a stock setup.

I am going to try to and figure out what was put into this car, but does anyone have any experience with any of the schrick cams? 280, 284 or otherwise? I'm deciding whether I should yank it on the rebuild or not (and no I'm not doing a crazy rebuild, just a overhaul/refresh).

Thanks,
Kai
 
Well, after nearly 30 years she fired up. Injection seems fine, including cold start injector, Amazing. I have a few other things to work out before driving, but the fuel management seems A ok.
 
Have been reading through the book - what a great resource. I'm annoyed at myself that it took me this long to try to understand our fuel injection systems. I had been told that D-jets were mechanical fuel injection, but I see that is not at all correct. That you again for this brilliant resource!
 
Well xing sounds like a book I should also read, as my d-jet isn't as sorted as I originally thought. I also would like a better understanding. Good subject.
 
Definitely. I actually learned a LOT about Bosch systems in toto - most of the concentration on pulsed injection is centered around L-jet. Once you have that down, he concludes with d-jet (since it was already way old technology, even when this book was published in 1989). L-jet was derived from d-jet, but once you understand L-jet, d-jet is easy as is motronic (which is essentially L-jet with ignition timing and some other stuff added on). It's kind of information dense - it took me a good two days to read through the first 30 pages and really understand the info, but I am SO glad that I did it. Should have done it 10 years ago.
 
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