Discussion
Over here, it should be labelled "Duty Cycle". If you look that up in the Bible or Service Manual it's a one-ended open port for measuring some electronic ignition value. (I just tried to look up what it measures in the service manual but couldn't find the reference to it.)
The ballast resistor is a thicker section of wire connected to the loom on both ends.
Grady
The ballast resistor is a thicker section of wire connected to the loom on both ends.
Grady
That depends if your car is running a ballasted coil rather than a 12V coil. It is common for the Ford to run ballasted as O.E. (the power for the 12V hot start jump comes from the starter motor). I have seen ballast wires (as Grady mentioned... they have male/male ends) in blue or grey tied in loops (they need cooling and are not normally IN the loom, they are also visibly thicker) to the chassis rails. The ceramic versions can be used for the heater one speed and dim-dip headlamps too (on some cars I have seen as many as 4). A@
Grady, I have spent time looking for a 'duty cycle' wire on the Ford 2.8 engine with no luck...any help on that would be great. I now have an 86 280DH (had an 83 back in the day) and all the wiring on mine is akin to the S Series 1 2.8 (I have an OE conversion to the purple relay from the Avant engine run sensor on this 86 car).
OP it would be good to know the year of your car and if it is the early black loom or the later coloured one... A@
OP it would be good to know the year of your car and if it is the early black loom or the later coloured one... A@
Adrian@ - Mine is an '86 too. I'm pretty sure the part is labeled Duty Cycle (or such). I think I'll be visiting the car later today and I'll double check.
I can't remember or find the reference to Duty Cycle. In the back of my mind I thought it was used for measuring Dwell but looking at the manual, Dwell is not settable. I'm sure I didn't dream it. I'll put more effort into looking.
And in answer to the OP's question, Yes, it just sits there, connected to nothing,
I can't remember or find the reference to Duty Cycle. In the back of my mind I thought it was used for measuring Dwell but looking at the manual, Dwell is not settable. I'm sure I didn't dream it. I'll put more effort into looking.
And in answer to the OP's question, Yes, it just sits there, connected to nothing,
Getting warmer. I may have gotten idea from Jim in New Mexico who said on the US forum:
I’ve attached my dwell meter to the duty cycle connection and set it at the recommended 30 degrees mark using the mixture adjustment screw. Runs great, and gets 20-22 mpg, depending on the type of driving.
and
My goal was to set it to allow the throttle plate to be closed as much as possible without stalling, and then set the idle speed with that screw. With that done, I set the idle mixture with a dwell meter connected to the duty cycle lead. Setting that required a readjustment of the idle speed, and once again the idle mixture. That was about it.
This 2017 thread had meandered around and we were talking about adjusting the "Do Not Adjust" adjuster and setting on the throttle. I'll reach out and sees what he remembers. Grady
I’ve attached my dwell meter to the duty cycle connection and set it at the recommended 30 degrees mark using the mixture adjustment screw. Runs great, and gets 20-22 mpg, depending on the type of driving.
and
My goal was to set it to allow the throttle plate to be closed as much as possible without stalling, and then set the idle speed with that screw. With that done, I set the idle mixture with a dwell meter connected to the duty cycle lead. Setting that required a readjustment of the idle speed, and once again the idle mixture. That was about it.
This 2017 thread had meandered around and we were talking about adjusting the "Do Not Adjust" adjuster and setting on the throttle. I'll reach out and sees what he remembers. Grady
Edited by Grady on Sunday 3rd December 17:29
Edited by Grady on Sunday 3rd December 17:30
Grady and Adrian,
I have that "Duty Cycle" wire on MCWEDGE, my '86 280i. It is not used to set the ignition dwell, although a dwell tach is connected to it to adjust the Duty Cycle, thus the mixture. Or vice versa. Here are the instructions from the TVRCCNA site:
You can adjust the mixture of the fuel by using a dwell meter. You need a long 3mm Allen Wrench also.
Hook up the dwell meter to the battery and the sensing lead to the "duty cycle" wire near the ignition coil It is blue and usually has a snap connector on the end to cover it. It should be labeled.
Set the meter to the 6 cylinder range
Run the car up to operating temperature
Insert the long 3 mm Allen wrench into the tube at the back of the metering unit. The tube is usually gold colored and may be plugged (but probably not, since these cars are old now). The tube is on the part of the metering unit that has injection tubing attached.
While the engine is running, gently turn the Allen wrench until the dwell meter reads about 30 to 32 degrees. Be careful and do not put pressure on the Allen wrench.
Rev the engine to 3000 rpm and hold for 10 seconds or so. After it returns to Idle, readjust if it is not holding about 30 to 32 degrees.
Hope this helps. I'll go take a photo of that wire lead and add it to this thread.
I have that "Duty Cycle" wire on MCWEDGE, my '86 280i. It is not used to set the ignition dwell, although a dwell tach is connected to it to adjust the Duty Cycle, thus the mixture. Or vice versa. Here are the instructions from the TVRCCNA site:
You can adjust the mixture of the fuel by using a dwell meter. You need a long 3mm Allen Wrench also.
Hook up the dwell meter to the battery and the sensing lead to the "duty cycle" wire near the ignition coil It is blue and usually has a snap connector on the end to cover it. It should be labeled.
Set the meter to the 6 cylinder range
Run the car up to operating temperature
Insert the long 3 mm Allen wrench into the tube at the back of the metering unit. The tube is usually gold colored and may be plugged (but probably not, since these cars are old now). The tube is on the part of the metering unit that has injection tubing attached.
While the engine is running, gently turn the Allen wrench until the dwell meter reads about 30 to 32 degrees. Be careful and do not put pressure on the Allen wrench.
Rev the engine to 3000 rpm and hold for 10 seconds or so. After it returns to Idle, readjust if it is not holding about 30 to 32 degrees.
Hope this helps. I'll go take a photo of that wire lead and add it to this thread.
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