1991_RS

OK, here's (yet) another timing question. With the timing set properly, the advance wire plugged in, and the motor warm, the timing does not advance (or advances negligibly) when the engine is revved. Engine 5.7 TPI (Speed Density) from a 1991 Z-28.

Am I missing something?

Procedure used to set timing: Warm engine. Disconnect advance wire near blower motor. Adjusted timing to 6* BTDC (although it ended up at closer to 9* after tightening the dist bolt). Reconnected the advance wire. Checked to see how timing was advancing and it wasn't.

Took the car for a test drive anyway and it runs good at any speed, but under hard acceleration, it lags for about 1 second before it accelerates.

Drac0nic

My advice is check the tan/black wire for 5V DC to ground. If you don't have it you need to troubleshoot your ECU and wiring. This is what causes the timing to "unlock." I've had this issue with an improperly wired relay board on my Megasquirt before.

Assuming you are checking by revving the engine with a timing light. You should be getting some advance (in the case of the MS I have the curve where it gets quite a bit of advance.) I would think it would be noticeable.

1991_RS

Thanks, DracOnic

Yes, we were using a timing light. When we rev it, the timing mark doesn't move past the "V" plate. Will check the wire for 5V to see if that is the problem.