timing question

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Aug 20, 2008 | 09:46 AM

heck

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Heel & Toe

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timing question

set the timing on my fresh 406 to 6 degrees base timing with ECM wire disconnected, then battery disconnect / reconnect, question is when I plug the wire back in / restart and watch the timing, what should the advance be at around 2500 RPM? I'm seeing 40 + degrees advance by the ECM, is this normal? That much sounds bad to me but there is no knock or ping, sounds fine.................any thoughts?

Aug 20, 2008 | 10:39 AM

1bigjim

Intermediate

Joined: Jun 2008

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[QUOTE=I'm seeing 40 + degrees advance by the ECM, is this normal? That much sounds bad to me but there is no knock or ping, sounds fine.................any thoughts?[/QUOTE]

I am going through the exact same thing, I am seeing 38 degrees and it jumps around. Did your idle jump up when you pluged the ECM wire back up?
I have a high idle issue (1,000 out of gear) and thought it was the timing.

Aug 20, 2008 | 10:52 AM

heck

Thread Starter

Heel & Toe

Joined: Nov 2007

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idle RPM increased slightly and smoothed out a bit, b I am idling around 700 - 800 RPM, just don't know why the advance goes so high when revving

Aug 20, 2008 | 12:26 PM

byebyeL98

Safety Car

Joined: Sep 2003

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From: Orange County NY

St. Jude Donor '10-'11-'12-'13

It depends on whether you are running a stock or custom tune. Either way, at 2500 rpms under virtually no load, 40 degrees is probably in the ball park.

At higher rpms (3000+) and very light loads, I run over 40 degrees of total timing with no issues.

Aug 20, 2008 | 01:39 PM

JAKE

Le Mans Master

Joined: Feb 2000

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From: Kempner Texas

Remember, part throttle timing and WOT timing are different. At part throttle you can see OVER 40 degrees BTDC under certain conditions.

Jake

Aug 20, 2008 | 10:09 PM

Iroc57

Melting Slicks

Joined: May 2007

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From: Warwick RI

Quote:

Originally Posted by heck

idle RPM increased slightly and smoothed out a bit, b I am idling around 700 - 800 RPM, just don't know why the advance goes so high when revving

The computer must advance the timing similar to the weight did on old distributors. 38-40 advance at 3K was not out of the ordinary. Don't sweat it

Aug 20, 2008 | 11:15 PM

rodj

Le Mans Master

Joined: Aug 2000

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From: Australia

Quote:

Originally Posted by Iroc57

The computer must advance the timing similar to the weight did on old distributors.

Exactly , that is why you have to disconnect the EST plug while setting base timing so it is not being advanced by the ECM

Aug 21, 2008 | 08:21 AM

heck

Thread Starter

Heel & Toe

Joined: Nov 2007

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Thanks guys, finished the fine tuning last night, left the timing alone thanks to your input, put the scanner on and everything looks great! no codes and in closed loop! woo hoo 406! power

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Aug 21, 2008 | 09:13 AM

Kubs

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From: Akron Ohio

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I am replacing the cam in my '90. This is my first cam replacement on a computer controlled car. I see you guys are talking about unpluging the ECM?? Wont it not run without it? What are you talking about more specifically?

Thanks (sorry for hijacking)

Aug 21, 2008 | 10:29 AM

#10

heck

Thread Starter

Heel & Toe

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To set the base timing you must unplug the wire to the ECM, this eliminates the computer from advancing it and allows you to get a true reading.

Aug 21, 2008 | 11:57 AM

#11

Kubs

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From: Akron Ohio

2025 Corvette of the Year Finalist - Modified

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2023 C5 of the Year Finalist - Modified

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St. Jude Donor '09-'10-'11

Quote:

Originally Posted by heck

To set the base timing you must unplug the wire to the ECM, this eliminates the computer from advancing it and allows you to get a true reading.

Is this on the dist.? Which one is it?

Aug 21, 2008 | 06:24 PM

#12

rodj

Le Mans Master

Joined: Aug 2000

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From: Australia

Quote:

Originally Posted by Kubs

Is this on the dist.? Which one is it?

Black plug on single wire (tan / blk ??? ), comes out of loom on firewall behind dist

Aug 21, 2008 | 06:59 PM

#13

Sinister87

Racer

Joined: May 2004

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From: VA

If you go buy a Haynes manual it does show a picture along with the location, you should buy a manual period good to have.

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