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Username Post: 86' K5 ESC Problems        (Topic#200653)
K5buddy 
Lurker
Posts: 6

Reg: 10-10-08
10-10-08 11:14 AM - Post#1539061    

I recently bought an 86 K5 BLazer with the LE9 305 H.O. in it and 86k. My truck ran perfect for the first two weeks but when I filled up with Shell gas, I keep hearing a pinging/kocking noise under load. It gets really loud. My Grandpa had a similar truck that would run the same on Shell gas but I dont think thats the problem. I learned that these engines have Electronic Spark Control (ESC) with a knock sensor. The ESC controls the timing (Retards or Advances when necessary). Is it possible that the ESC Module suddenly went bad or maybe the knock sensor? I'm getting VERY poor gas mileage (7-8mpg) and this noise is driving me crazy. Any Suggestions would be very helpful. I'm also looking for a parts place that sells the knock sensor and ESC module.

 
Vaughn 
"12th Year" Gold Supporting Member
Posts: 14669

Loc: Colorado Springs, CO
Reg: 08-08-04
10-10-08 01:56 PM - Post#1539176    
    In response to K5buddy

Try a higher grade of gas, until you have time to fix it.

If you also have the early computer control (ECM), you may be able to pull trouble codes off of it. The just-prior-to-TBI trucks had this computer control, and your truck is the last year produced with a carb before the TBI came out.

Yes, your ESC chip (inside distributor) may not be working right, and so might your knock sensor. The ESC chip has a habit of going bad, and creating a lot of problems. That is what I would replace first, if you don't get a trouble code or you don't have the ECM. The knock sensor would be next.

Get AC Delco replacement parts from Napa, you don't want the cheap Autozone or Checker parts, they are not reliable.

Don't attempt to get junkyard parts - especially on the knock sensor, they are year specific - if you get the wrong year it won't work at all.

 
Bad Bowtie 
Senior Member
Posts: 4469
Bad Bowtie
Age: 41
Loc: TX
Reg: 07-04-03
10-11-08 08:53 AM - Post#1539629    
    In response to Vaughn

Or you could bypass the ESC all together which is what alot of us truckers do. Simply unplug the harness running from the right firewall going to the distributer and splice 2 wires together on the distributer side of the pigtail. I think it is the brown & pink wire? I might be wrong though as it has been some time ago that I did this to my '83 Silverado. You can use the "SEARCH" function above and find the exact 2 wires to splice together, as this mod was discussed less than 4 months ago...
GMC. We are Professional Grade.

http://www.cardomain.com/id/2004VHO


 
Smokey 
Senior Site Adminstrator
Posts: 17447
Smokey
Age: 65
Loc: "Small town USA"
Reg: 12-06-99
10-11-08 04:29 PM - Post#1539853    
    In response to K5buddy

First thing to do is unhook the spark control computer lead from the pink wire and hook the pink wire directly to the dist. cap. Make sure you plug it into the cap at the BAT terminal. The second thing is to locate the 4 wire connector that feeds into the ignition module. There's a brown (D), green (C), white (B), and black (A) wire there. The letters in () are on the black clip that the wires come out of. You cut the green (C) and black (A) wires between this clip and where they go into the distributor. Then all you need to do is solder the 2 cut leads from the dist/ignition module together, i.e. the green and black ones, (make sure to tape the exposed wires) and now your HEI distributor will function just as a pre ESC model does. I did this and it has been running fine for well over a year now.

Dan

Note: Here is a photo I made of the plug which goes to the ESC control and feeds the ignition, which Dan mentioned above. I labeled the wires which need to be cut and showed which wires are A, B, C and D.



That's it. Of course you will need to adjust the timing when you get it running. This mod converts your truck back to a regular HEI ignition, without all the electronic controls. You will have to monitor your spark knock yourself since you won't have the ESC to do it for you. If you have ever had an older vehicle you know how to do this anyway, why do you need the ESC to do it for you?

Thanks go to Swerve for this info
'67 427 Chevy C-10
'79 454 surburban
'89 454 1 ton dually
'03 V-Star 1100


In Memory of CT's Mike McVeigh and Ron Schrapp (aka rons56)


 
Petroholic 
Contributor
Posts: 839
Petroholic
Loc: Moses Lake, Wa.
Reg: 08-12-05
10-11-08 09:28 PM - Post#1540069    
    In response to K5buddy

I don't know where you are from, but out here in WA. state, most the Shell stations have gone to 10% ethanol.
I've got a 07 Silverado Classic w/flex fuel that pings a tiny bit on the 87 w/10%. Seems maybe they haven't got the blends down right yet.
If I'm buying the ethanol, I get the 89 midgrade or 92 super, and it goes away.



 
Petroholic 
Contributor
Posts: 839
Petroholic
Loc: Moses Lake, Wa.
Reg: 08-12-05
10-11-08 09:31 PM - Post#1540072    
    In response to Smokey

Great post!

I was just asking questions about this on another thread.

Thanks!

Is the EMC going to cause problems, like check engine lights?



Edited by Petroholic on 10-11-08 09:32 PM. Reason for edit: No reason given.

 
Smokey 
Senior Site Adminstrator
Posts: 17447
Smokey
Age: 65
Loc: "Small town USA"
Reg: 12-06-99
10-12-08 02:04 PM - Post#1540424    
    In response to Petroholic

  • Petroholic Said:
Is the EMC going to cause problems, like check engine lights?



I'm thinking you mean the ESC
But no, none not at all.
'67 427 Chevy C-10
'79 454 surburban
'89 454 1 ton dually
'03 V-Star 1100


In Memory of CT's Mike McVeigh and Ron Schrapp (aka rons56)


 
Petroholic 
Contributor
Posts: 839
Petroholic
Loc: Moses Lake, Wa.
Reg: 08-12-05
10-12-08 08:47 PM - Post#1540728    
    In response to Smokey

  • Smokey Said:
  • Petroholic Said:
Is the EMC going to cause problems, like check engine lights?



I'm thinking you mean the ESC
But no, none not at all.



No. Meant ECM.
Will it cause problems?



 
Smokey 
Senior Site Adminstrator
Posts: 17447
Smokey
Age: 65
Loc: "Small town USA"
Reg: 12-06-99
10-12-08 10:13 PM - Post#1540773    
    In response to Petroholic

Nope. Just make sure you go back and set the timing.
'67 427 Chevy C-10
'79 454 surburban
'89 454 1 ton dually
'03 V-Star 1100


In Memory of CT's Mike McVeigh and Ron Schrapp (aka rons56)


 
K5buddy 
Lurker
Posts: 6

Reg: 10-10-08
10-24-08 09:26 PM - Post#1549410    
    In response to Vaughn

FYI!! ESC is NOT in the distributor...It's under the passenger side dash and looks very similar to an ECM. I just got done replacing it and my truck is still running like poopoo.

 
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