85 auto. Have code 43 popping up on hard acceleration sometimes. Can hear the knock or rattle that appears to be coming from the distributor. I have changed the knock sensor and the ESC module and I still get the knock. I have then put better gas and additive in plus gas line antifreeze in. Still getting the noise. Checked the grounds on the engine LH side below the valve cover to the frame all good, as well as the on the one on the LH side head at rear..all clear. have cleared all codes out a few times and it still comes back as soon as the noise appears(check engine light comes on and the code is set). Any suggestions before I pull the rest of my hair out :D . It almost sounds like a lifter rattling, can this cause it??? just a thought as the car is higher milage.

Thanks for any help Ron D

 

Code 43 happens when the ECM tries to force a knock during warmup but doesn't detect one. In the middle/late 80's when a higher octane unleaded first became available, code 43's were popping up all over the place, so GM issued a memcal replacement to correct this. You are actually hearing a knock though, so it's a bona fide code 43. Assuming the new knock sensor was torqued to the proper spec range, you most likely have a wiring problem. There are some excellent troubleshooting tips here:
http://www.applink.net/cct/tips/code43.html

 

What is the proper torque spec???? its tight but my books dont show a spec for it. it shows the other sensor's, but not the knock.

 

14 ft lb (19 N m)
It's hidden in the "driveability and emissions" section of the Helms manual.

 

Ron D

I have the same problem with my '85. If you read the owner's manual it states that only 87 octane is needed. I was placin 93 in the tank .
I purchased the car new and this happens everytime that 93 octane is pumped. I have also changed the knock sensor
and the ESC module. The problem still exists. I discussed this with a Chevy mechanic that deals specifically with TPIs
he told me that the system does try to detect a knock by advancing the distributor once during every start-up at close to full throttle.
The problem is that the 93 octane does not allow the system to detect detonation.

Seriously try to go to a mid grade fuel or back to 87 octane. The early TPI only have 9 or 9.5:1 compression so high
octane fuel is not really needed.

Pete

 

Thanks for all the tips guys. I put 92 octane in it with a boost and it still pings. I guess from what your saying this may not be the best thing to do. Darn it anyway. It almost makes one wonder if all the compter stuff really helps that much, as it seems cause more problems than it solves half the time :D

 

To add to the brain damage :D I have run a direct ground from the module to the frame and still no better. the car runs great once the code is set. I get no more ping or anything, just smooth acceleration all the way up. clear the codes again and the ping is back until it ping's again and then runs fine again. The check engine light is on full time when the ping happens. any more suggestions guys, I am minutes away from screamming very LOUD at the car

 

Ron,
I have also battled the Code 43 Demon. Here's my experience...

I had just recently rebuilt the entire car and was trying to get it road worthy when I started having problems. Code 43 was 1 of 4 codes I was getting at the time. What I learned is that the ECM is in Open Loop mode until the coolant reaches 195F... this assuming stock EPROM is still in place. During this time the knock sensor circuit is not active. How it can check for knock... or if it even does so is beyond me. Only after 195F will the ECM switch to closed loop. When the coolant is above this setpoint and the knock sensor detects detonation this signal is sent to the ECM via the ESC module. The ECM will then attempt to adjust the timing until the detonation is no longer detectable. If the ECM cannot remove the detonation it will set a Code 43 and put the car in "Limp Home Mode". When this happens a loss of power may be evident.

What I found is that I had the aux fan cooler and knock sensor connectors swapped when I was hooking the harness back up... easy enough because they are roughly the same length, same connector, and on the same side of the motor(85).

I would suggest you check continuity between the knock sensor and the ESC for starters. Thats how I found my error. Email me if you want to chat further...

 

Ron D, I also had this problem. After spending hours and hours and hours and well you know what I mean. I gave up and took it to a shop and another shop and another shop and well you know what I mean. It turned out to be two problems first the wire you need to unplug to check your timing was shorting out on a plug wire, and second and this is what gets me, no one out of 5 shops including me checked the timing it was 18 DEG off :confused: when the puter advanced the timing for the knock test the timing was just coming up to were it should have stared at so it kicked a code.
Long story short, Start with the basic check your timing.

 

I Have checked it and I think a little more adjustment and I'll have it. I have just moved the distributor abit at a time to see and the sounds are getting less and less every time I move it. I also added a large ground(over kill) to the module wire. With the combination of the two it seems to be getting very close.

Ron D

 

Well, I have checked and re check all the grounds and I still get the knock or ping in the distributor. I have gone so far as to change the distributor, cap and rotor. It had a crack in the magnet below the pole piece. It is jumping around with codes like there is no tomorrow. get 12 - no prob all is normal, 24 - no prob its not moving, get 34 off and on, no rhyme nor reason for that ??? its only once in a while, 42 once in while also and 43 most of the time. I am really starting the think the ECM is screwed.

As I said previously, When it sets code 43 it runs great and has no ping at all, anyone else want to make a shot in the dark here. I am just about ready to go :crazy:

Thanks to all of you that have put in there two bits - muchly appreciated, Ron

 

Check the wiring to the fuel pump relay located on the firewall driver side between engine and brake booster.This was one of the problems in my 85 there was a short their. Could also be this relay it's about $10.