Timing change???
Thread Starter
Drifting
Joined: Oct 2001
Posts: 1,444
Likes: 4
From: Hawthorne NJ
Timing change???
Set the timing with the EST bypass wire disconnected, when I got 6 degrees, I locked dist, then replugged EST bypass wire. Should I have seen the timing mark move?
Just wondering...
Just wondering...
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 412
From: WV
Yes , as soon as you plug the EST wire back in the computer takes over the timing .....WW
Thread Starter
Drifting
Joined: Oct 2001
Posts: 1,444
Likes: 4
From: Hawthorne NJ
Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
Not necessarily...if the ECM needs to advance or retard it CAN after the EST is reconnected...its not necessarily a GOT to kinda thing at that moment, after all, if the engine is running fine, there is no need. The ECM needs to see some new data before it makes any changes anyway, like o2 or MAF or TPS change...etc then its motivated to move the timing as needed.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
On my car the ECM sets the timing to 20° BTDC at idle. That will cause the timing mark to move toward the 12:00 position on the harmonic balancer. I just took a peek at mine and it moves about an inch.
Last edited by Cliff Harris; Sep 12, 2013 at 02:31 AM.
Thread Starter
Drifting
Joined: Oct 2001
Posts: 1,444
Likes: 4
From: Hawthorne NJ
When does this happen? Are you just checking at a random time, not unplugging the EST, and you notice the timing is about an inch above the timing tab?
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
I have a timing tape on my harmonic balancer. I just did a timing chain replacement and did not set the timing then (been meaning to get to it -- just forgot). Your post reminded me so I went to the garage and adjusted the timing to 6° (it was 4°). Then I reconnected the EST connector and rechecked the timing and it was 20°. Surprised me because I thought the ECM added 20° to the 6° for a total of 26°, but that was not the case. I looked for the timing mark but couldn't see it because various things were in the way. I moved around and was able to see it about an inch above where it is with the EST connector open. I tried to take a picture but the timing light doesn't put out enough light for my camera.
Another way to look at it is that the timing moved by 14° so that would be roughly an inch on the circumference of the harmonic balancer. It's late and I need to get up at 4:00 AM tomorrow or I would calculate the amount...
Another way to look at it is that the timing moved by 14° so that would be roughly an inch on the circumference of the harmonic balancer. It's late and I need to get up at 4:00 AM tomorrow or I would calculate the amount...
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