A noise filter on the ground to the block? Can this be possible?

[winchy2]

Hi guys,

Hopefully someone would have seen this at some point in time. I have been chasing ground issues for a long time. I finally saw that the one going to the left top side of the block although connected, had the ring bent and broke off when I wiggle it. I figured I would redo the entire ground line and started undoing the harness until I hit something that looked like a lot of wrapped electrical tape but it wasn't. It was hard plastic and I had already cut into it. I have no idea what it is and the electronics seem to sit between the coil ground wires. My harness was made by Painless Performance over 15 years ago. I just called them and they said they did not know what it was.
My gut tells me it may have been some kind of rudimentary noise suppressor. What I want to know is if it's safe to cut these electronics off and ground directly to the block. Maybe this will get rid of my ground ghosts.

IMG_7440 copy.jpg IMG_7441 copy_s.jpg

Thanks!

[dave w]

Maybe a RC Filter? I see a resistor, maybe the yellow part is a capacitor.

https://en.wikipedia.org/wiki/RC_circuit

dave w

[winchy2]

Thanks Dave. Maybe something along those lines. Thing is there are three components that I can see.

10K OHM Resistor
.033uF (Possibly a Coupling capacitor yellow)
Ceramic capacitor of unknown value brown (Possibly a bypass capacitor)

[1project2many]

Oh... this is a Vette application? I had a 95 at the shop once that had all sorts of ABS issues that weren't actually ABS issues. Turned out someone had removed the noise filter which was allowing the tach signal to show up on the RF brake wire which was tricking ABS.

https://www.corvetteforum.com/forums...lter-on-a-95-a.

https://www.corvetteforum.com/forums...this-part.html

[winchy2]

No, this '95 LT1 was out of a Z28 and these components seem to be attached to the ignition coil. I am leaning to just remove them but not sure if it is OK to ground the ignition coil to the block straight up. Anyone else has any other ideas?

[joukoy]

No, this '95 LT1 was out of a Z28 and these components seem to be attached to the ignition coil. I am leaning to just remove them but not sure if it is OK to ground the ignition coil to the block straight up. Anyone else has any other ideas?

http://shbox.com/1/95_ign_system_schematic.jpg

Coil is not directly connected to ground.

[winchy2]

Well, I think I am getting close to figuring this out. Looks like my '95 F-Body was wired as a Y-Body a while back. I found this diagram that now makes a lot more sense.

Y-B-Tach.jpg

With that info, I went onto looking for that darn filter, which I don't even know I need mind you, and found this device (tach filter)

newfilter.jpg

Which looks identical to the one I hacked up. Seems to be an original GM part. Now the question is, should I replace this or can I just join the wires and be done with this?

[joukoy]

Well, I think I am getting close to figuring this out. Looks like my '95 F-Body was wired as a Y-Body a while back. I found this diagram that now makes a lot more sense.

Y-B-Tach.jpg

With that info, I went onto looking for that darn filter, which I don't even know I need mind you, and found this device (tach filter)

newfilter.jpg

Which looks identical to the one I hacked up. Seems to be an original GM part. Now the question is, should I replace this or can I just join the wires and be done with this?

Remove or replace.
If you join wires, something will break (short circuit)

[dave w]

Everyone will have an opinion one way or the other.

Try without the tach filter, no cost? If something seems not right, spend money.

dave w

[1project2many]

No, this '95 LT1 was out of a Z28 and these components seem to be attached to the ignition coil. I am leaning to just remove them but not sure if it is OK to ground the ignition coil to the block straight up. Anyone else has any other ideas?

Right. The tach filter (also identified as a noise filter in some documentation) is connected to the ignition - connection. In the Corvette I repaired, a previous owner had opted for "I'll go without this device" which created significant electrical noise in the engine and chassis harness. The most significant effect of this unwanted interference is that the right wheel speed would seem to increase then decrease extremely rapidly which would cause the ABS system to release the RF wheel which resulted in a pull to the left. Lesson learned for me? Don't remove the noise filter.

The coil frame does not need to be connected to ground. The primary side receives power from the IGN+ wire and is grounded by the ICM. The return path for the secondary circuit is through the block to battery - to battery + to IGN+ to the coil.

The Corvette engines used a black, plastic encapsulated filter as in the links I posted. I have not had to chase this part in an F or B body application.

[winchy2]

All this makes a lot of sense now. And yes, I have been reading how detrimental it can be to remove as it is designed to smooth out the signal specially with HEI systems. Yet other people seem to be doing fine without it.
I am trying to find the same original GM but I may have to go with aftermarket if nothing pans out.