I was trying to diagnose some surging and cold idling problems on my car. I checked the timing (89 IROCz 5.7 TPI) and it was right at 6 degress with the EST wire disconnected. Then I reconnected the wire to see if it was advancing properly and to my surprise the timing mark went about an inch off the tab - and that was still at idle without any reving. I also noticed a change in the exhaust odor - I think it smelled a littler richer.

So my "basic timing question" is: What should the timing normally be at idle but with the EST wire still connected?

Thanks!

 

Try a dial-back timing light (Craftsman makes one, sold at Sears) to determine exactly how many degrees of advance the car has at idle with the plug connected.

I'd expect the computer to advance the timing somewhat, but it shouldn't be 36 degrees or something high like that.

 

Idle timing with the EST plugged in could easily be 20-25 degrees, but not much over that. If it went off the tab or timing marks then something is wrong somewhere....

 

actually that sounds pretty normal to me. when I check timing with the computer connected, first of all the car idles at 7-800 rpm and yes the timing is well off the tab.

When I disconnect the est it goes back to 6up.