memcal/ignition module issue??
Thread Starter
Instructor
Joined: Jun 2010
Posts: 248
Likes: 2
From: Avon IN
memcal/ignition module issue??
Greetings,
My 1990 is throwing Code 43 whenever it starts. I have modified it with a 383, superram, afr heads and supporting mods. The chip is a pcmforless mail order tune. I have replaced the knock sensor, new plug wires and plugs, new cap, new coil, new rotor. Voltage at knock sensor is 4.97 and the ground is good. I replaced the computer around 4 years ago with an aftermarket.
While driving with a scanner hooked up I see absolutely no retard of timing when the engine light comes on. Car never loses power. One thing I have noticed is that every time the car is started it seems to have to relearn like if I disconnected the battery. It also stinks pretty bad.. but I think that has a lot to do with the tune and lack of cats. Idles fine around 1000.
I have read up on threads that have similar issues, I can't decide if I should replace the Ignition module or memcal or both. Or maybe it is something else entirely.
The motor was just rebuilt. Any help is appreciated.
My 1990 is throwing Code 43 whenever it starts. I have modified it with a 383, superram, afr heads and supporting mods. The chip is a pcmforless mail order tune. I have replaced the knock sensor, new plug wires and plugs, new cap, new coil, new rotor. Voltage at knock sensor is 4.97 and the ground is good. I replaced the computer around 4 years ago with an aftermarket.
While driving with a scanner hooked up I see absolutely no retard of timing when the engine light comes on. Car never loses power. One thing I have noticed is that every time the car is started it seems to have to relearn like if I disconnected the battery. It also stinks pretty bad.. but I think that has a lot to do with the tune and lack of cats. Idles fine around 1000.
I have read up on threads that have similar issues, I can't decide if I should replace the Ignition module or memcal or both. Or maybe it is something else entirely.
The motor was just rebuilt. Any help is appreciated.
Last edited by cypher85; Apr 10, 2015 at 12:33 PM.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
The PCM tests the knock system at startup. To see if this is the problem: clear codes, start engine, turn off engine, check for codes. If you have a code 43 it means the knock sensor or ESC (Electronic Spark Control) is not working.
I think the ESC function was moved into the PCM around 1990. Do you have an external ESC module? Does your MEMCAL have an ESC module? Maybe a better question to ask is: did your original MEMCAL have an ESC module and does the new one not have it?
For reference, this is what an external ESC module looks like:
The part on the left is the ESC module incorporated into the MEMCAL (you should be able to see it through one of the holes in the blue cover):
I think the ESC function was moved into the PCM around 1990. Do you have an external ESC module? Does your MEMCAL have an ESC module? Maybe a better question to ask is: did your original MEMCAL have an ESC module and does the new one not have it?
For reference, this is what an external ESC module looks like:
The part on the left is the ESC module incorporated into the MEMCAL (you should be able to see it through one of the holes in the blue cover):
Thread Starter
Instructor
Joined: Jun 2010
Posts: 248
Likes: 2
From: Avon IN
The PCM tests the knock system at startup. To see if this is the problem: clear codes, start engine, turn off engine, check for codes. If you have a code 43 it means the knock sensor or ESC (Electronic Spark Control) is not working.
I think the ESC function was moved into the PCM around 1990. Do you have an external ESC module? Does your MEMCAL have an ESC module? Maybe a better question to ask is: did your original MEMCAL have an ESC module and does the new one not have it?
For reference, this is what an external ESC module looks like:
The part on the left is the ESC module incorporated into the MEMCAL (you should be able to see it through one of the holes in the blue cover):
I think the ESC function was moved into the PCM around 1990. Do you have an external ESC module? Does your MEMCAL have an ESC module? Maybe a better question to ask is: did your original MEMCAL have an ESC module and does the new one not have it?
For reference, this is what an external ESC module looks like:
The part on the left is the ESC module incorporated into the MEMCAL (you should be able to see it through one of the holes in the blue cover):
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Drifting
Joined: May 2013
Posts: 1,736
Likes: 31
From: Reno Nevada
The ESC is on the memcal in your 1990, and if PCM for less provided you with a tune most likely it came with a piggyback adapter, and not a memcal replacement, so your original ESC is being used? See here to test said circuit:
http://www.chevythunder.com/esc_map_code_43.htm
http://www.chevythunder.com/esc_map_code_43.htm
Thread Starter
Instructor
Joined: Jun 2010
Posts: 248
Likes: 2
From: Avon IN
Sorry Cliff I should have said that the test you described was the first thing I did before replacing the knock sensor and checking the wiring. After I replaced the knock sensor I cleared the codes and 43 popped up again.
Thread Starter
Instructor
Joined: Jun 2010
Posts: 248
Likes: 2
From: Avon IN
The ESC is on the memcal in your 1990, and if PCM for less provided you with a tune most likely it came with a piggyback adapter, and not a memcal replacement, so your original ESC is being used? See here to test said circuit:
http://www.chevythunder.com/esc_map_code_43.htm
http://www.chevythunder.com/esc_map_code_43.htm
Drifting
Joined: May 2013
Posts: 1,736
Likes: 31
From: Reno Nevada
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