Recently when I start my car the rpms drop below idle (1000rpm) to around 500 then jumps back up. I usually give it gas to get it up so the car won't stall. Is this caused by a bad timing chain, or is it something else?

 

Timing chain? Ehhh...dunno, put a timing light on it with the EST disconnected, and see if your base timing is walking around a bit.


The dip on startup....could be a few things. Done a tuneup recently? Check your plugs and wires,plugs may be a little old. Generally a dip like that is a 'rich dip'....either from getting too much fuel, or weak spark. But there's many many potential causes. Check the simple stuff first. After you give it more gas does it run better and smooth out, or try to drop again?

 

Base timing is checked with the Set Timing Connector disconnected.

It's the connector coming out above the larger wire loom in the picture blow.

Disconnect it, start & hold the rpm steady, if the timing walks, check your chain, gears, and distributor, I'd start with the dizzy.

 

make sure your choke is working properly

 

How exactly does the chock work, I know I have an electronic one.