This topic was originally "Cold Start Injector", but I've got a new question. What is the procedure to set the timing on a '87 GTA, LB9 305 / 700R-4? I read on another site to jump the A&B terminals on the ALDL connector (diagnostic mode) to set the base timing. Now I have just read to disconnect the brown/black striped wire next to the heater box/fan housing. I'm afraid this may have been my problem all along.

------------------
'80 Firebird
355 c.i. Chevy (built)
8.39 E.T. (1/8 mile) Altitude Corrected - 8.27
In the process of being rebuilt and getting 7-second-ized
'87 GTA
Stock LB9 5.0 / 700R-4 / 3.42 gears
T-Tops

 

Both are supposed to accomplish the same thing, which is preventing the ECM from advancing the timing. The preferred method is to simply just disconnect the brown/black wire.

------------------
1989 IROC-Z 5.7L

 

Thanks Omar. That makes me feel a little better. Because I also read to "NEVER" start the engine with the ALDL jumpered. I thought this was pretty stupid, since you have it running at times if you have a scanner hooked up. Oh well...thanks again.

 

Okay, here's the way I do it.

Start the engine and let it rear normal operating temperature and allow the ECM to go into closed loop.

Shut down the engine and disconnect the EST connector (brown wire with a black stripe) and connect the timing light.

Start the engine, which may a little hard to start with the EST connector disconnected.

Wait until engine reaches a steady idle.

Now check the timing with the timing light and adjust it as needed.

Once the adjustment is complete, shut down the engine, reconnect the EST timing connector and disconnect the battery for at least 30 seconds to clear the error code the ECM set when it detected the engine running w/o the EST connector connected.

Start engine and drive the car at normal throttle settings to allow the ECM to re-learn the settings that were lost when the battery was disconnected.

Hope this helps.

Jake

------------------
1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9

 

A good way to set timing without a light is with a vacume gauge. diconnect the dist plug, and advance timing untill you reach max vacume, back off two inches of vacume.
This will be within 1 degree.

------------------
Iroc 350 5 speed