so i finally got it to start. its between 6-12 degrees but flucuates while running. i know that i'm supposed to disconnect the EST and re-time it but it wont start with it disconnected and dies if i disconnect it while running. what do i do?

 

You shouldn't connect or disconnect the EST wire with the engine running or the ignition in the "ON" position. That can cause a voltage spike that'll kill the ECM.

I think all you need is more timing advance to keep it running with the EST disconnected.

Start the engine with the EST connected and let it warm up thoroughly.

Once it's warmed up, shut down the engine and disconnect the EST wire, start the engine and see if it'll idle on its own.

It may be difficult to keep it running, but play with the throttle to try to keep it from dying out. If you CAN get it to idle on its own, set the timing at 6 degrees BTDC, lock down the distributor, recheck to make sure you still have 6 and, if you do, shut down the engine. Now disconnect the battery for 30 seconds to clear the error code. Then reconnect the battery and EST. You're done.

If you still can't keep it running, shut down the engine, disconnect the battery for about 30 seconds to clear the error code that gets set when the ECM detected the engine running with the EST disconnected.

Reconnect the EST and battery and start the engine again. Now with the engine running advance the timing more. Your TDC mark should be just off (toward the 12 o'clock position) the scale on the timing chain cover timing tab with the EST connected.

That'll put your timing in the range of 20 degrees or so, which is about right for what you need to do next.

Let the engine run until fully warmed up again, then shut it down. Disconnect the EST then refire it to see if the engine will now idle on its own. If it will set the base timing as above. Don't forget to clear the error code when you're done.

Usually with the base timing set at 6 degrees BTDC and the EST connected, the timing at idle will be in the low 20's. Your scale probably won't read that high, so the TDC mark on the damper will be just off the scale.

Keep me posted.

Jake

 

well put Jake

 

ok, i followed your exact steps. the problem is that when i disconnected the est and set to 6 degrees it worked, when i disconnected the battery and pluged the est back in the timing is still of the tab like at about 20 degrees. i also put it in drive and it about damn neared died on me. would a faulty knock sensor have something to do with this?

 

Let me see if I can explain how it works.

The ECM controls the ignition timing. It causes the timing to advance or retard based on the input of various sensors.

With the EST wire disconnected, you've taken the ECM out of the loop, it no longer can control the timing. With the EST disconnected, the engine will only run on a small amount of timing that is contained in the distributor module.

So, to set the base timing, you disconnect the EST. Once it's set to 6 degrees BTDC, or whatever you decide to use, you have to shut down the engine and reconnect the EST.

You must also disconnect the battery for 30 seconds or so because when the engine idling with the EST DISCONNECTED, the ECM detected that and set a code. It "thinks" there is a problem. Disconnecting the battery clears that.

Now, when you reconnect the EST and the battery and fire the engine, the ECM again takes over the timing and it should be in the low 20s at idle.

So if the base timing is set to 6 * BTDC AND the ECM advances the timing to somewhere in the low 20s, then everything, as far as timing is concerned, seems to be okay.

Now, if the engine still wants to die, then you've got another problem. Probably the IAC, TPS or 02 sensor.

The IAC controls the idle speed based on input from the ECM. It sends, what is referred to as 'counts' to the IAC to cause the IAC's pintel to extend or retract to maintain the correct idle speed. That idle speed is burned into the PROM.

There's a manual procedure for resetting the IAC to give the ECM a new base for calculating the counts. It's posted in the Tech Tips section on the Forum. I have it saved as a doc file in case you can't find it; email me and I'll send it to you jakejr266@sbcglobal.net

You'll need a digital voltmeter to set the voltage on the TPS. The stock setting is .54 volts, +/- .075. Many guys report having better throttle response with a setting of .60/.62

The 02, is another matter. Without a program to read the 02's activity, or lack thereof (LOL), you need Diacom, ScanTool or something like AutoXRay. This is the only way I know of to see if yours is lazy or not.

You can jumper the A&B terminals of the ALDL to see if your system is going closed loop. First install a jumper wire, then start the engine. The SES will flash at different intervals depending on whether the system is in open loop of closed loop. I believe one blink per second indicates closed loop operation. Open loop blinks faster (I'm going from memory on this though).

If you installed a performance cam in the engine, chances are the idle speed burned in the PROM is too low for the engine to idle well. The way to address that is with a PROM reburn to set the idle speed higher.

Keep me posted.

Jake