D-Jetronic FI points

B

Bwana

Well-Known Member
Messages
1,211
Reaction score
84
Location
Santa Fe, NM
Heading off to Amelia this weekend, I was thinking about the condition of the car. Of great interest is the TPS, which was replaced with a "better" one last year and the FI timing points, down inside the distributer. The car has either 80,000 or 180,000 km on it and I doubt the FI points have ever been replaced. And they look it.

I got a new set from BMW and finally decided to install them. What could go wrong? No adjustment, just a straight bolt in!

Well, the new ones didn't produce any fuel whatsoever. Many removals/installations and checks to no avail. I have to mention that I dropped the original 4mmX.7 screws that hold the points plate to the distributer into the bowels of the machine and so replaced had to replace them with brand new ones from Home Dumpo. Long story short, they were about 2mm too long and so either grounded out the points by touching the spring or held the points phyisically open (didn't check which). Result=no fuel.

I found a great guy here in town that is both helpfull and cooperative (!!!!) who checked a number of things including ignition and fuel injector operation. He sent me home with a list of "to do" things around the distributer which is when I found the too long bolts. By about 2mm.....sigh....

I had removed the distributer and checked everything inside (Petronix) which was when I found the bolt length. All back together with the inevatible "one tooth off" but after i got that sorted it fired up.(ALWAYS MARK YOUR DIZZY TIMING AT TDC BEFORE DOING ANY OF THIS. Remember, it turns like 1/4 turn because it has bevel gear drive and so is not a straight pull out). Still rough so back to the guy's shop for him to do further diagnosis.

We have to dig thru some of the books to refresh our memories of how the D-Jet works as opposed to other similar, but later, systems.

The D-Jet gives fuel pulses in two banks, 3 cylinders at a time, correct? What is the firing order of the BMW 6 cylinder?

Stay tuned!
 
Thanks for the support! Like I told Steve, we'll be there in a BMW, which one is still open :grin:
 
Firing order is 1-5-3-6-2-4

I am keeping the faith!

Last minute tranny mount installed and wine loaded up.

Crappy weather though...
 
Update

OK, here's the rest of the story. Apparently I'm my own worst enemy. When I installed the too-long-bolts into the points carrier and tehy contacted the backside of the points spring, it appears one of them took the power signal from the computer straight to ground and overloaded one of the power transistors. The circuit board even smells a little burnt.

EDIT: There are three pins on the plug from the computer into the points. The center goes directly back to the computer and the outer two are power signals (#21 &22) from the computer to fire an injector. We get 6.7 VDC on one of the outer pins and nothing on the other. According to the wiring diagram, there should be power on both outside pins.

I spoke with a couple of the acknolwedged experts here and both were of the opinion that these computers haven't gone bad for 35 years. I appear to be the first doofus in 35 years to have installed too-long-bolts :(

So now I'm in the market for a functional computer. There's an outfit in Germany that apparently rebuilds them, I may check it out.

http://www.eps-elektronik.com/index_en.php

Alternatively, we could fix the computer if we had a detailed wiring diagram, including wire colors and component specifications.

Does anybody have a wiring diagram of the actual computer, not just the car diagram?

Also, any faults in our logic? Any D-Jet experts jump in here and comment!
 
Last edited:
You must log in or register to reply here.
Back
Top