Important Wiring Question

[Nick88]

IDK, it may work, it may not. The Knock Sensor works on resistance so, if you loose, or change it, you may have issues. There's a reason GM did things, mostly expense but it could be "cross talk" between different sensors/components. What I was asking, did you check the ground wire from the ESC to its grounding point? If it's still good, why f**k with it? If you do, try to get it as close to OE as possible.

Im more concerned if the wire might have any breaks or chaffing inside the harness or hidden, and my opinion is extra grounding could never hurt, which is why I want to splice a new ground along with the old ground. I just dont want to have to deal with chasing down issues that are a bad ground that is hard to trace is all. I just was worried about adding another ground might short something or cause some issues maybe with another sensor but Im not sure how. Mostly worried about ecm issues. The knock sensor wire I want to replace because the heatshield for it by the trans is pinned between the hot trans bellhousing and the passenger exhaust manifold, with the wire touching the manifold side of the heatshield touching the manifold, so I figured i might as well run a new wire just in case that wire is shorting sometimes or melted in some way, causing timing to retard like how it is. Mostly I just want to rule out every possible cause before I throw an ESC at it for like $150.

 

[Scooterwrench]

On my 1988 k5 Blazer 350 tbi i want to work on the esc to narrow down a timing issue, I want to rewire the ground of esc to manifold and run a new wire to the knock sensor. I have a red wire, blue wire, black/red, and black wire running to the esc. Which wire is for what? Any help is appreciated.

What is the timing issue you're trying to fix?

 

[Nick88]

What is the timing issue you're trying to fix?

Ive been having an issue where when i start accelerating, the timing retards. So the truck ends up being completely dead basically under light acceleration. When I rev it slightly with timing light it advances and revs up then immediately retards and bogs a bit. I have a new distributor and ICM, new connector for ESC and KS, new KS, new wire to KS, new coil, and Ive made sure there is no exhaust rattles or anything that can show up as knocking. You can really feel it accelerating out of a stop because it kicks up good then falls on its face immediately.

 

[Nick88]

I just want to get the damn thing fixed, all my ignition parts are brand new it gets frustrating quick, im gonna try to add the second ground and see if that helps, I just replaced the KS wire to seemingly no effect.

 

[Nick88]

Alright, so I added a second ground point on the manifold off the esc and now i have code 43... I guess the esc is only supposed to be grounded through ecm?? I grounded the black wire, I believe that is the ground on esc connector/ harness

 

[Caman96]

So you asked for help. You ignored it. Now you have a new code.
My point being, you have an issue and your experimating.

 

[Scooterwrench]

Ive been having an issue where when i start accelerating, the timing retards. So the truck ends up being completely dead basically under light acceleration. When I rev it slightly with timing light it advances and revs up then immediately retards and bogs a bit. I have a new distributor and ICM, new connector for ESC and KS, new KS, new wire to KS, new coil, and Ive made sure there is no exhaust rattles or anything that can show up as knocking. You can really feel it accelerating out of a stop because it kicks up good then falls on its face immediately.

Ignition timing is supposed to retard during loaded acceleration. Put everything back the way it was then set the initial timing with the bypass wire disconnected. You can add as much as 6 deg. to your base timing but start out with 2 and see how it responds.

 

[Nick88]

So you asked for help. You ignored it. Now you have a new code.
My point being, you have an issue and your experimating.

I didnt ignore the help, I just firgured Id try it just in case considering it took me 2 minutes to do and 5 seconds to cut the wire and the code dissappeared and the wiring is exactly how it was again. Im not ignoring, Im just trying to make 100% sure before I replace another part, especially an expensive one, that I try every single possible way of anything.

 

[Nick88]

Ignition timing is supposed to retard during loaded acceleration. Put everything back the way it was then set the initial timing with the bypass wire disconnected. You can add as much as 6 deg. to your base timing but start out with 2 and see how it responds.

I set timing to 0 and 2 independently when I replaced the distributor. The timing retarding isnt like a regular retard its very heavy, probably over 6+ degrees retarding almost immediately, so I increase rpms but the truck is still at around 12-14 degrees of timing.

 

[Nick88]

Could it possibly be the ICM 4 prong connector behind distributor? If the connector is worn or corroded would that be able to cause an issue similar to mine?? Thats the last original pigtail in the ignition system, if its not that connector the only parts I can imagine it being are either the ESC or the ECM