Early GM obd2 question.

Tech questions that don't fit above forums

Moderator: Team

Post Reply
crazyman
Expert
Expert
Posts: 976
Joined: Sat Oct 27, 2007 4:53 am
Location: Yorkville, Illinois (60 miles SW of Chicago)

Early GM obd2 question.

Post by crazyman » Sat Oct 23, 2010 1:27 am

The spark retard from the knock sensor. Does it pull it all at once, or is it variable retard based on voltage output?

Thanks.

In-Tech
Guru
Guru
Posts: 1510
Joined: Wed Apr 21, 2010 4:35 am

Re: Early GM obd2 question.

Post by In-Tech » Sun Oct 24, 2010 2:51 pm

crazyman wrote:The spark retard from the knock sensor. Does it pull it all at once, or is it variable retard based on voltage output?

Thanks.
What year/engine? I'll look up the code when you provide the info.
Heat is energy, energy is horsepower...but you gotta control the heat.
-Carl

In-Tech
Guru
Guru
Posts: 1510
Joined: Wed Apr 21, 2010 4:35 am

Re: Early GM obd2 question.

Post by In-Tech » Sun Oct 24, 2010 8:53 pm

Here's a screen shot of a '96 Chevy PU Vortech 350 knock attack table. As far as I know, all GM ecm/pcm's have an attack and decay rate. So, to briefly answer your question, it ramps up to gain control and then continually tries to decay it out as long as there is no knock. Hope this helps.
Attachments
KnockAttack.JPG
KnockAttack.JPG (100.65 KiB) Viewed 684 times
Heat is energy, energy is horsepower...but you gotta control the heat.
-Carl

crazyman
Expert
Expert
Posts: 976
Joined: Sat Oct 27, 2007 4:53 am
Location: Yorkville, Illinois (60 miles SW of Chicago)

Re: Early GM obd2 question.

Post by crazyman » Mon Oct 25, 2010 10:16 pm

Thanks In-Tech!

Post Reply