twin plugs

[TheTopher]

it doesnt turn off during starting. it turns off when the truck goes into closed loop (the engine is at running temp and computer begins to take info from sensors) so ur engine is hot enough to burn off the excess gasses on its own. when the engine is starting, both coil packs are used.

That makes a lot of sense.


After my earlier post I unplugged the driver side set of plugs and the truck also started. Plus that would also explain why it started running better when it warmed up...the misfiring set of plugs was disabled.

 

[shadetree]

After my earlier post I unplugged the driver side set of plugs and the truck also started. Plus that would also explain why it started running better when it warmed up...the misfiring set of plugs was disabled.

It has nothing to do with open/closed loop, nothing.

"Dual Plug Inhibit (DPI)
Both left and right side plugs fire at the same time when the engine is running. When it is cranking, however, only the right set of plugs fire. During cranking, the control module signals the DIS module through the Dual-Plug Inhibit (DPI) circut to inhibit or restrict the left set of plugs from firing."

From: Ford Fuel Injection and Electronic Engine Control, by Charles O Probst, SAE.
Page 126, last paragraph.
shady

 

[TheTopher]

That doesn't exactly do a very good job of explaining why my truck managed to start with only the "inhibited" set of plugs hooked up. Is there a failsafe of some sort?

 

[skyy_4life]

well i heard from the guys at atuozone (not like their smart) that it turns off when it gets warmed up.

 

[Bryan22]

i'm not gonna say either way on that. but i would look for a more informed source to quote than 'the guys at autozone'

 

[Sevensecondsuv]

+1. Most of the people I've been err, "forced" to deal with at autozone can't tell the difference between a dipstick and a battery.

 

[Sevensecondsuv]

There could be a whole host of reasons why yours started with the passenger side unplugged. I'll start with a few to get your imagination going:

1. The DPI circuit in the ECM has failed.
2. The DPI circuit in the DIS module has failed.
3. The DPI wire has corroded and become grounded between the ECM and DIS module.
4. You have the passenger side trigger wires plugged into the driver's side coil and vice versa.
5. etc, etc, etc