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Posted by: jc914 Jan 17 2009, 08:40 AM

On the FI Brain unit what does the top knob that comes out of the unit do. I have tried searching but i cannot find direct information on it.....
thanks

Posted by: Jeff Bowlsby Jan 17 2009, 08:56 AM

Idle mixture adjustment only.

Posted by: jc914 Jan 17 2009, 08:57 AM

Thanks for the fast reply

Posted by: gothspeed Mar 26 2009, 08:36 AM

Can a 1.7 D-jetronic be made to handle a bigger motor? It is my understanding that the 2.0 uses the same system, though most certainly uses a different fuel map. Has anyone uprated this D-jetronic for more engine capacity?

Posted by: roadster fan Mar 26 2009, 09:43 AM

Gothspeed take a look at the picture below. Not gonna have a fuel map on these boards since it uses all discreet components. The ECU's were changed over the years for improved performance (emissions, overrun, fuel enrichment, etc) but by changing the circuits on the board. The manifold pressure sensor is the key component in determining injector pulse width, as D-jet is a speed density system. It uses the Injector trigger contacts to measure engine speed.

Everything you want to know about D-jet ECU's is here http://members.rennlist.com/pbanders/ecu.htm#Introduction. Check out the other areas of his site for information about all the components of the system. Awesome.

Jim

Posted by: roadster fan Mar 26 2009, 09:47 AM

Oh almost forgot, the MPS has been adjusted by some people to handle the changes in engine build parameters. I think Bleyseng on this board still does this. There are probably a couple of threads here discussing this. Hope this helps,

Jim

Posted by: gothspeed Mar 26 2009, 10:48 AM

Awesome posts roadster! Is it possible the injectors themselves are the same as the 2.0? Mine is the 1.7 1973 D-jetronic CA and it seems to work pretty well except it loses some power up top, which may be the throttle switch or just the modest power of the motor . I like the fuel injection so I was thinking of adding a big bore kit and some mild porting to pep it up a tad. Other than that I am really liking my new 914 !!


I will look into that site to gain as much info as possible ............ thanks for the help!!

Posted by: roadster fan Mar 26 2009, 01:19 PM

Three different types of injectors IIRC, yellow top 1.7, green top 1.8, black top 2.0. I think some aftermarket ones mess with easy color identification.

Shouldn't be a problem to keep it D-jet, but you may have to get some 2 ltr D-jet parts depending on how much you change internally . The ECU, MPS, Injectors, Throttle Body, TPS, etc should be matched to work right. Some parts can interchange, but check out the D-jet site for compatiblity. Orange914 built a 2056, had the MPS adjusted, and said he was happy yesterday. I heard it fire right up after sitting for some time.

Jim

original poster sorry

Posted by: jc914 Mar 27 2009, 06:09 AM

Thanks for the Hijack the information provided is perfect

Posted by: Dave_Darling Mar 27 2009, 09:39 AM

Green plastic == 2.0 injector
Yellow plastic == 1.7 injector
Black plastic == early 1.7 injector, possibly from a VW application
Blue or purple == 1.8 injector

Aftermarket injectors can be different colors, of course.

--DD

Posted by: gothspeed Mar 27 2009, 10:41 AM

So seeing how the 2.0, 1.7 & 1.8 injectors are different colors, I would assume that can be interpreted that they have different flow rates? What other 'component' differences between the 1.7 & 2.0 D-jetronic are you aware of?

As I mentioned earlier I will be going with a 8:1 compression 96mm big bore kit, mild porting and maybe even a 2.0 cam if there is a difference ....