• Welcome Visitor! Please take a few seconds and Register for our forum. Even if you don't want to post, you can still 'Like' and react to posts.

Engine dis/edis grounding........


shadetree

New Member
Joined
Sep 9, 2007
Messages
1,794
Reaction score
9
Points
0
Age
84
Location
East Texas
Vehicle Year
1994
Make / Model
Explorer Sport
Engine Size
4.0
Transmission
Automatic
What is ground? In the automobile application, it is a 0 voltage reference point, or a return path for current, or both. The engine is is most always at battery ground if wired properly.

Current/voltage has to come from somewhere, it cannot be generated from thin air without some type of device to do so. The vehicle has a battery to supply electrical power. The battery will have a positive connection and a negative connection. The negative connection in most modern applications is considered as ground. In early automotive designs, the positive terminal was used as ground.

The spark plugs are screwed into the engine block which is at ground potential, and the plug centers are attached to the ignition coil secondary wiring in a series circuit configuration. Although, the coil secondary in the dis/edis system is not physically connected to the block directly, the current path does go thru the sparkplug to engine ground completing the current path.

The attached diagram is from "How to Understand, Service, and Modify Ford Fuel Injection & Electronic Engine Control," by Dr. Charles O. Probst, SAE, page 125. Who is Dr. Probst?
http://www.bentleypublishers.com/author.htm?who=Charles_O._Probst,_SAE
It shows how grounding is achieved in this configuration. The engine block is the return path for current, hence, ground.

Those who are interested, and kinda understand electrical circuits can determine from themselves whether or not there is a ground.
 

Attachments

Last edited:


Bob Ayers

New Member
Joined
Aug 28, 2007
Messages
2,274
Reaction score
16
Points
0
Location
Durham, NC
Vehicle Year
1999
Make / Model
Ranger
Transmission
Automatic
What is ground? In the automobile application, it is a 0 voltage reference point, or a return path for current, or both. The engine is is most always at battery ground if wired properly.

Current/voltage has to come from somewhere, it cannot be generated from thin air without some type of device to do so. The vehicle has a battery to supply electrical power. The battery will have a positive connection and a negative connection. The negative connection in most modern applications is considered as ground. In early automotive designs, the positive terminal was used as ground.

The spark plugs are screwed into the engine block which is at ground potential, and the plug centers are attached to the ignition coil secondary wiring in a series circuit configuration. Although, the coil secondary in the dis/edis system is not physically connected to the block directly, the current path does go thru the sparkplug to engine ground completing the current path.

The attached diagram is from "How to Understand, Service, and Modify Ford Fuel Injection & Electronic Engine Control," by Dr. Charles O. Probst, SAE, page 125. Who is Dr. Probst?
http://www.bentleypublishers.com/author.htm?who=Charles_O._Probst,_SAE
It shows how grounding is achieved in this configuration. The engine block is the return path for current, hence, ground.

Those who are interested, and kinda understand electrical circuits can determine from themselves whether or not there is a ground.

Shady, the only current path from the POSITIVE battery terminal to the NEGATIVE battery terminal (GROUND if you wish) with the DIS/EDIS coilpack is in the primary windings, where open collector drivers GROUND the second primary winding terminal (the first is tied to 12V) which creates a di/dt that induces a voltage into the secondary windings. High voltage is generated
differentially across the two secondary winding terminals and the current flows between these terminals, NOT back to the battery from the engine block!

 

shadetree

New Member
Joined
Sep 9, 2007
Messages
1,794
Reaction score
9
Points
0
Age
84
Location
East Texas
Vehicle Year
1994
Make / Model
Explorer Sport
Engine Size
4.0
Transmission
Automatic
Shady, the only current path from the POSITIVE battery terminal to the NEGATIVE battery terminal (GROUND if you wish) with the DIS/EDIS coilpack is in the primary windings, where open collector drivers GROUND the second primary winding terminal (the first is tied to 12V) which creates a di/dt that induces a voltage into the secondary windings. High voltage is generated
differentially across the two secondary winding terminals and the current flows between these terminals, NOT back to the battery from the engine block!
I didn't say that the secondary connected to the battery. I was simply stating that power has to come from somewhere, and there has to be a complete circuit. This holds true for the secondary circuit in the coil as well. If there is no loop in the secondary circuit, it is an open circuit, and there is no current flow. The circuit is complete as indicated in Dr. Probst's schematic, and he does indicate grounding.:)shady
 
Last edited:

Bob Ayers

New Member
Joined
Aug 28, 2007
Messages
2,274
Reaction score
16
Points
0
Location
Durham, NC
Vehicle Year
1999
Make / Model
Ranger
Transmission
Automatic
I didn't say that the secondary connected to the battery. I was simply stating that power has to come from somewhere, and there has to be a complete circuit. This holds true for the secondary circuit in the coil as well. If there is no loop in the secondary circuit, it is an open circuit, and there is no current flow. The circuit is complete as indicated in Dr. Probst's schematic, and he does indicate grounding.:)shady

Shady, obviously you can't read a schematic! The current in the secondary winding flows from one secondary terminal to the other secondary terminal!
I've labeled the terminals + and - Once again, there is NO GROUND reference with the secondary winding, and no current flows back to the battery from the secondary winding. To get GROUND current, the secondary winding would have to have a connection to GROUND (like a center-tap) which it does not have!
 
Last edited:

shadetree

New Member
Joined
Sep 9, 2007
Messages
1,794
Reaction score
9
Points
0
Age
84
Location
East Texas
Vehicle Year
1994
Make / Model
Explorer Sport
Engine Size
4.0
Transmission
Automatic
Shady, obviously you can't read a schematic! The current in the secondary winding flows from one secondary terminal to the other secondary terminal!
I've labeled the terminals + and - Once again, there is NO GROUND reference with the secondary winding, and no current flows back to the battery from the secondary winding. To get GROUND current, the secondary winding would have to have a connection to GROUND (like a center-tap) which it does not have!
I am perfectly capable of reading a schematic. Keep your snide remarks to yourself. Again, I did not say it connects to the battery ground for current flow from the battery. I said the engine block completes the circuit. If the block is not there, there will be no current flow in the secondary winding as it will be an open circuit. The current is generated in the secondary from the collapsing magnetic field of the primary winding. If there is nothing attached to the secondary winding for a load, there will be no current flow. If there is a load, but the circuit is open, there will be no current flow. Being that the part of the circuit that completes the secondary winding loop is the engine block, this could be considered ground as it is fixed and does not change. If you don't mind, I will go with Dr. Probst schematic and not yours. And why all this is such a big deal to you:dunno::dunno::)shady
 

Bird

Member
Joined
Aug 6, 2007
Messages
252
Reaction score
5
Points
18
Location
San Antonio, Tx.
Transmission
Automatic
In a sense, you're both correct - in the Ford EDIS setup, the block only serves as a 'path' to complete each secondary circuit whereas, in 'most' of the other engine circuits, the block is a physical grounding point of the negative battery terminal. In the single coil systems the block is the actual 'ground'. In modern vehicle electronic control systems, the ground from the battery is usually provided through the pcm to trigger events such as injector firing, coil primary pulsing, etc.

Bird
 

Bob Ayers

New Member
Joined
Aug 28, 2007
Messages
2,274
Reaction score
16
Points
0
Location
Durham, NC
Vehicle Year
1999
Make / Model
Ranger
Transmission
Automatic
In a sense, you're both correct - in the Ford EDIS setup, the block only serves as a 'path' to complete each secondary circuit whereas, in 'most' of the other engine circuits, the block is a physical grounding point of the negative battery terminal. In the single coil systems the block is the actual 'ground'. In modern vehicle electronic control systems, the ground from the battery is usually provided through the pcm to trigger events such as injector firing, coil primary pulsing, etc.

Bird
Correct Bird, the injector coils are fired very similar to the coilpack primary windings.
 

shadetree

New Member
Joined
Sep 9, 2007
Messages
1,794
Reaction score
9
Points
0
Age
84
Location
East Texas
Vehicle Year
1994
Make / Model
Explorer Sport
Engine Size
4.0
Transmission
Automatic
In a sense, you're both correct - in the Ford EDIS setup, the block only serves as a 'path' to complete each secondary circuit whereas, in 'most' of the other engine circuits, the block is a physical grounding point of the negative battery terminal. In the single coil systems the block is the actual 'ground'. In modern vehicle electronic control systems, the ground from the battery is usually provided through the pcm to trigger events such as injector firing, coil primary pulsing, etc.

Bird
Correct, and in the conventional coil system, the coil is an "autotransformer." The primary and secondary windings are the same wire. The winding is tapped at some point to ground to make the primary and secondary circuits. As indicated in Dr. Probst's schematic, the block serves the purpose of completing the circuit, and has 0vdc, satisfying the definition of a ground. He designates each plug as positive ground and negative ground.:)shady
 

Bird

Member
Joined
Aug 6, 2007
Messages
252
Reaction score
5
Points
18
Location
San Antonio, Tx.
Transmission
Automatic
Good, now let's all gather around the kawana bush, hold hands and sing "kumbaya".



Bird
 

dennis461

New Member
Joined
Aug 18, 2007
Messages
356
Reaction score
2
Points
0
Location
Waterford, South Jersey
Vehicle Year
1996
1991
Make / Model
Ford
Jeep
Engine Size
3.0l
Transmission
Automatic
And,
Is it a clean ground or dirty ground?
Wait a minute, aren't the tires insulators???
 
Last edited:

shadetree

New Member
Joined
Sep 9, 2007
Messages
1,794
Reaction score
9
Points
0
Age
84
Location
East Texas
Vehicle Year
1994
Make / Model
Explorer Sport
Engine Size
4.0
Transmission
Automatic
And,
Is it a clean ground or dirty ground?
Wait a minute, aen't the tires insulators???
Damn, another out of work comedian wannabe.:Dshady
 

Sponsored Ad


Sponsored Ad

Members online

Today's birthdays

Member & Vendor Upgrades

For a small yearly donation, you can support this forum and receive a 'Supporting Member' banner, or become a 'Supporting Vendor' and promote your products here. Click the banner to find out how.

Latest posts

Truck of The Month


Kirby N.
March Truck of The Month

Recently Featured

Want to see your truck here? Share your photos and details in the forum.

Follow TRS On Instagram

TRS Events

25th Anniversary Sponsors

Check Out The TRS Store


Sponsored Ad


Sponsored Ad

Sponsored Ad


Amazon Deals

Top