Electrical Archaeology Part II

304065 · 01-15-2002, 04:10 PM

Ladies and Gentlemen,

The mystery continues. . . the PO installed an MSD 6AL box and tach adapter. The factory CDI box remains in place (anybody know what BHKZ stands for, auf Deutsch?) but the wires were unplugged and laying in the engine compartment. Believing as I do that unnecessary wires are not only confusing but a fire hazard, I removed the blue with yellow stripe, red and black wires that have a three-prong plug for the bottom of the CDI on one end, and go to the 14-pin connector, an abadoned distributor lead and into the console. These were in one harness and it was a simple matter to remove the pins from the 14-pin connector (and note the variation in my log book for future generations).

Here's the QUESTION: the harness running from the CDI box also had a braided ground connection that led to a tab on the bottom on the box, between the cooling fins. This ground strap divided into 2, one was connected to the coil bracket and the other to the left timing chain cover. My guess is that the engine gets an adequate ground through the trans strap, and these were merely grounds for the CDI box for interference purposes, but does anybody know if they are essential to proper operation?

A bonus question: There are two additional wires that stick out of the firewall ahead of the oil pressure sender: these are a small brown and white, and a small yellow. Anybody know what their function is? I checked the wiring diagram but am unable to find anything that would make sense.

Thanks in advance,

John

'88 Carrera 3.2
'71 E

Roland Kunz · 01-20-2002, 03:26 PM

Hello

anybody know what BHKZ stands for, auf Deutsch?

B osch
H ochspannung
K ondensator
Z ündung

The CDI wireloom can stay and just isolate the connectors.
Only the red wire is hot the others will not see power and the red wire has a seperate connector some 4" down the 3 spade connector. So leave it on and avoid geting dirt or something else in there. If you need it you just connect the red wire and the trigger contact and the CDI is back to buisiness.

The shielding from the engine to the CDI box is very important and should work propper.

If you have start problems or other ignition relatet then check the ground. Everything abouve 10 OHM isn´t good.

Other point with the CDI is that sparks runing back via the cables can jump into the ignition harness and hit the CDI box.

Bonus question:

71 E ?

brown white is normaly used for the cruise control valve actuator.
Yellow is the starter selenoid.

But it also could be a remaining leftover from the MFI coldstartdevice ( two temperatureswitches in the breather tower )

Well that is Early S Theritory

Warren really seem to have problems.

Grüsse

304065 · 01-28-2002, 07:06 AM

Ladies and Gentlemen,

In case anybody comes this way again, the factory ground wire to the CDI unit IS required for proper engine operation, even though the CDI box has been disabled. After removing the unit from the console and the associated wiring, I fired the engine up only to discover that it sounded like it was running on three cylinders- and on acceleration would throw tons of gray smoke. Thinking it could be the ground, I insalled a factory grounding strap from one of the motor mount bolts to one of the bolts on the chain cover-- and voilla, all six cylinders. Evidently the grounding strap on the transmission is not sufficient to properly ground the ignition.

John

'71 E (still running rich)
'88 Carrera (makes you appreciate Motronic)

Roland Kunz · 01-29-2002, 10:29 PM

Hello

Yupp

Warren told so, so must be.

Grüsse