Against good advice from this forum, I rebuilt the engine on an 87 convert. that a friend overheated--split radiator tank cooked engine. Have less than a $1000 in the engine and had some fun on the rebuild. Anyway, the rebuild went well with help from a local engine rebuilder who redid the lower block for me [pistons, rods, mains, etc].

Problem: cant get / keep timing set correctly. Initially set timing at 10 degrees B-TDC and engine started fine. Have since tried repeatedly to reset to factory spec of 6 degrees BTDC but get really rough idle, pre-ignition, and constant "Check Engine Soon" light. Shop manual refers to by-pass "electronic timing control if so equipped" but cant find anything on distributor that matches ETC description -- only external connection from distro [besides tach and bat] is the 4-pin plug and engine wont start/run with it disconnected. I've triple checked distro gear position on cam and installed new plug wires.

Leaving the timing at 10-12 degrees [according to timing light] allows engine to run well, coolant temp remains at 200-205, and no "check engine" light. So-- what have I missed/what could be wrong?

 

The connector is cylindrical in shape and should be below relays, beside booster.




The problem is, at idle with EST bypass connected, there is about 26* of advance and your retarding it to the point of barely running.
With EST bypass wire disconnected, you will loose the 20* of advance that the EST adds.

 

hope this help

[IMG][/IMG]

 

Jack-pot--saw the word "Tach" on the distro top and didnt realize the brown lead was also the ETS. Looks like a secondary connection/wire extension has been added on to the primary brown lead coming out of the wiring loom. The brown wire extension has the same mail/female connections and at the mid-point, there is a cylinder-shaped metal container with a strap/bolt hole--looks like some sort of damper device for reducing radio interference or something. Anyone know what the purpose of the wire extension and metal cylinder is???

 

I may be wrong, but I think the wire you are holding goes to the tach filter. If you follow the 4 wires that go to the connector from the distributor down along the firewall away from the distributor, you will find the connector. I know what I just typed is confusing, but follow the 4 wires away from the distributor.

 

Tach filter

 

383vette--so what you are saying is the ETS lead is one of the 4 wires in the 4-plug connecter at the back of the distro????? I didnt pay that much attention when I reconnected the 4-plug to the distro but thought all four wired went into the large wire loom at the firewall. Not much room to maneuver/trace wires, probably need to remove distro cap {again} to identify the right lead/connection. Appreciate the help.....

 

I just happen to be pulling my motor tonight. I snapped a picture of the connector you are looking for. Good luck. Willie

 

Post #4 shows the correct connector. Real easy to find, breaks out of the harness next to the FP relay.

Joel

 

On the L98 it's a single wire connector that you disconnect when setting the base timing.
- Get the engine up to operating temp and shut it down
- Unplug the connector
- Start the engine again and set the base timing
- Tighten down the distributor hold-down clamp
- Double check the timing and then turn the engine off
- Reconnect the connector
- Good to go

 

Nope, look farther above the 4 wire connector toward the firewall. There is a single wire connector that needs to be disconnected to set the base timing. The single wire connector in post #4 goes to the tach filter which does nothing to the base timing.

 

Nope. Not on my '90. Brown wire, white stripe as shown in post 4. It's in the FSM

 

I know that the '88-'89 has the same brown wire deal on the odd bank side. The connector location may vary by year but pulling the wire in CF 383 pic effectively disconnects the "advance" portion of the spark control module....does the same thing. Toma-to/To-ma-to

 

I am quickly learning that the location of "things" varies from year to year with Vetts--I know, big dah! Anyway, found the ETC wire/connector on the wire loom next to the power brake vac shell. Was able to accomplish the base timing set and engine does run better but still seem to have some sort of ECM issue. Plan is to take car into local Vette-shop for diagnostics--have gone as far as I can with out more "facts". Thanks to everyone for their quick and informative responses....great forum a newbie!!!!

 

Nice to be able to disagree with someone without World War III breaking out. Been there, done that in C6Z section.