Spark advance question (LT1)
Thread Starter
Melting Slicks
Joined: Sep 2003
Posts: 2,269
Likes: 118
From: N. Babylon NY
Spark advance question (LT1)
Hi,
I have been chasing a code 43. I looked in my shop manual but can not find what the spark advance should be on a 1992 LT1.
With my Autoxray scan tool it shows at idle spark advance at 23-24 degrees with 0 knock count.
When the (code 43) comes on, the knock count goes to 1-2 degrees and when I rev the motor spark advance goes up to 39-41 degrees.
This isn't right is it?
Thanks,
Steven
I have been chasing a code 43. I looked in my shop manual but can not find what the spark advance should be on a 1992 LT1.
With my Autoxray scan tool it shows at idle spark advance at 23-24 degrees with 0 knock count.
When the (code 43) comes on, the knock count goes to 1-2 degrees and when I rev the motor spark advance goes up to 39-41 degrees.
This isn't right is it?
Thanks,
Steven
Thread Starter
Melting Slicks
Joined: Sep 2003
Posts: 2,269
Likes: 118
From: N. Babylon NY
Just wanted to add something,
Sometimes with the Engine light on (code 43) the Autoxray shows 0 degrees of knock retard and normal spark advance (timming). Other times (with light on) it shows 1-4 degrees of knock retard. When light is off everything scans normal.
Thanks!
Steven
Sometimes with the Engine light on (code 43) the Autoxray shows 0 degrees of knock retard and normal spark advance (timming). Other times (with light on) it shows 1-4 degrees of knock retard. When light is off everything scans normal.
Thanks!
Steven
Safety Car
Joined: Feb 2002
Posts: 4,212
Likes: 10
From: Sun City West Az
Are you running headers? If so, I have heard that the knock sensors may be picking up some of the vibrations. I'm running JBA shorties and have had my 92 throw code 43 several times. I changed out both sensors and so far so good. 
Thread Starter
Melting Slicks
Joined: Sep 2003
Posts: 2,269
Likes: 118
From: N. Babylon NY
ittlfly,
Thanks!
Running stock exhaust. However there is a slight exhaust leak.
I have been chasing this for a while now. I thought it could be the wires as they were arcing. When I changed the wires with Taylors 8mm it was fine for the first drive (about 1 hour) next day light came back (code 43). I noticed that the new wires were also glowing and arcing in some places. And yes all the wires are neat and not touching anything. I called Taylor and they said it could be a bad set and to return them. Now I am going to try a stock set of A/C Delcos.
Also I checked the circuit and all checks out.
Thanks again,
Steven
Thanks!
Running stock exhaust. However there is a slight exhaust leak.
I have been chasing this for a while now. I thought it could be the wires as they were arcing. When I changed the wires with Taylors 8mm it was fine for the first drive (about 1 hour) next day light came back (code 43). I noticed that the new wires were also glowing and arcing in some places. And yes all the wires are neat and not touching anything. I called Taylor and they said it could be a bad set and to return them. Now I am going to try a stock set of A/C Delcos.
Also I checked the circuit and all checks out.
Thanks again,
Steven
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Race Director
Joined: May 2001
Posts: 14,165
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Originally Posted by bogus
timing advance is a function of the optispark.... makes me think it could be weak.
You have to look at all the conditions involved when the retard occurs. What is the MAP pressure like? RPM? Coolant Temperature? Intake Air Temperature?
Unfortunately the spark advance / retard functions are complicated.
