Setting Ignition Timing On A 90 L98

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May 23, 2004 | 10:10 PM

90Indy

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From: Forney Texas

Setting Ignition Timing On A 90 L98

I am trying to set the ignition timing on my 90 L98. The correct procedure requires the ECM be disconnected from the distributor. When I disconnect the ECM the engine will not start. With the ECM connected, I can not see the timing mark anywhere on the harmonic balancer. I would assume not seeing the mark with the ECM connected is normal.

My question concerns my inability to start after disconnecting the ECM. Does anyone else have this problem? If you do, how do you get around it? I have finished installing some mods and I am trying to get the last piece of the puzzle in place.

90Indy :nopity

May 23, 2004 | 10:13 PM

scorp508

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From: Boston, MA

Re: Setting Ignition Timing On A 90 L98 (90Indy)

Ok, it is the EST that is supposed to be disconnected. Are you disconnecting the correct thing? It should be a brown single wire connector somewhere near your brake booster. Sometimes it is buried in a big wire harness the first time you find it.

May 23, 2004 | 10:22 PM

90Indy

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From: Forney Texas

Re: Setting Ignition Timing On A 90 L98 (90Indy)

I don't have it in front of me but I could swear my manual states to disconnect the ECM. I like your idea better. What is the EST? I do remember a wire near the brake booster. I will give it a try. Many thanks for your input.

90Indy

May 23, 2004 | 10:25 PM

scorp508

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From: Boston, MA

Re: Setting Ignition Timing On A 90 L98 (90Indy)

Electronic Spark Timing :) Good luck!

1. Disconnect the EST
2. Start engine
3. Set timing
4. Turn engine off
5. Reconnect EST

May 23, 2004 | 10:29 PM

65Z01

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From: SE NY

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Re: Setting Ignition Timing On A 90 L98 (90Indy)

That's it; open the connector in the Tan/Blk wire just below the brake booster and follow Brian's directions above.

Opening the EST connector removes ECM control from distributor timing.

May 24, 2004 | 01:42 PM

JAKE

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From: Kempner Texas

Re: Setting Ignition Timing On A 90 L98 (90Indy)

You've been disconnecting the wrong thing. Disconnect the wire that the other guys told you about (single wire; tan with black stripe).

Be sure to disconnect the battery for about 30 seconds when you're done to clear the error code that gets set.

Jake

May 24, 2004 | 05:39 PM

Toymans85

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From: Barrie Ontario

Re: Setting Ignition Timing On A 90 L98 (90Indy)

My underhood sticker shows timing an automatic in drive with the EST diconnected and maual trannies in nuetral.

How much does it matter whether it is timed in drive or nuetral.
Anyone know?

Mine is an 1985 and is set to 6 degrees