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Aug 1, 2001 | 01:20 AM

GRX

Thread Starter

Le Mans Master

Joined: Jul 2001

Posts: 6,252

Likes: 2

From: Silicon Valley Kalifornia

Can anybody help me determine the correct spark advance while idling or in cruise? My diacom shows 0 degrees while idling. It shows 0 degrees when I start out. I don't have any error codes set.

Aug 1, 2001 | 02:49 AM

88L98

Drifting

Joined: Nov 2000

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From: Big D Tx

Cruise-In II Veteran

if i remember correctly, my scan software says im getting about 13-14 degrees advance at idle. are you talking about advance? you should be seeing more than 0 degrees. how it running?

Aug 1, 2001 | 09:29 AM

GRX

Thread Starter

Le Mans Master

Joined: Jul 2001

Posts: 6,252

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From: Silicon Valley Kalifornia

It was running kind of rough; but not very noticeably rough. Enough for me to notice.
No error code though.

Aug 1, 2001 | 12:01 PM

DOCTOR J

Burning Brakes

Joined: May 1999

Posts: 760

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From: Greenwich, CT

I'm guesing you have around a '90 vette. If so, there are several tables in the ECM that control spark. One of them will show 0* advance relative to ref at 0 TPS in closed loop (if I recall it right) - at that point spark is being controlled by another table, which would be applying about 20* total advance for idle. Diacom should be showing two spark readings - one w/r/t ref, the other total BTDC. They should not both be 0*. That's my guess, anyway. YMMV.

DrJ

Aug 1, 2001 | 01:59 PM

GRX

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Le Mans Master

Joined: Jul 2001

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From: Silicon Valley Kalifornia

It's an 85.

Aug 1, 2001 | 02:06 PM

Goody

Le Mans Master

Joined: Oct 2000

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From: Oak Harbor WA

Leaving diacom out of it for a bit, have you run a timing light on it?

Aug 1, 2001 | 03:37 PM

GRX

Thread Starter

Le Mans Master

Joined: Jul 2001

Posts: 6,252

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From: Silicon Valley Kalifornia

Not recently. A few weeks ago I went through the timing setup procedure before the smog test-car passed perfectly. I guess I should recheck it before anything else.