I adjusted the timing to 8 degrees and then reconnect the ecm wire and then i check the timing again and its like 20+ degrees causing the engine to stall. What can cause the ecm to advance the timing that much or why. no vacuum leaks to be found, cleaned the IAC, new plugs, rotor and caps, wires are in good shape, and the car hasnt beening running for one year. but the engine seems to run fine if i disconnect the ecm wire and stays at 8 degrees. the engine ran perfectly before installing headers and exhaust. thanks

 

20deg or so is where most GM configs I've seen put the timing at idle, with it varying a few degrees in both directions as the engine operates. Yours sounds like normal behavior except for the stalling.

If it ran OK before the headers and exhaust, chances are you may have damaged a wire. Is the check engine light on?

May be time for a scanner to check sensor inputs, especially the O2 sensor. It's common for new header installations to leave the O2 sensor wire routed wrong and have it melt. Same for the knock sensor wire.

 

There is a brown wire that connects to the dist. called the ESC connector, when its plugged in timing will change on the fly (advance/retard). You need to disconnect that wire when you set/check base timing.

 

I was assuming that was what he meant by "ecm wire" but who knows. Sounded that way from his description at least.

Kinda early in Hawaii to be up posting, isn't it?

 

so its normal for idle to be 20 degrees btc when the book says 6? well i did unplug the ecm or ecs wire first to do the timing. also the o2 is new, double checked the knock sensor, all thats left is to check the tps sensor. i have read the technical article, but it does not state which of the connectors to make make a jumper for? the tps has 3 connectors, which two do i jump. or any other ideas?

 

The book is telling you to dial in 6deg BTDC for initial timing, with the EST disconnected.

When you reconnect the EST, the ECM takes over and as I said above most GM software I've seen puts the timing in the 20deg ballpark at idle.

 

well i checked the tps sensor and it checks out ok, still no engine codes, any ideas on what else to check?

 

It was so early I didnt even notice he said ecm wire LOL.

Did you delete EGR when you swapped headers? Also, did you check the fuel psi during erratic behavior?

 

do i didnt touch the egr, its still hooked up just like stock, i didnt check fuel pressure just because it runs ok at high rpms, it just doest idle when setting in drive or reverse and not moving, it idles just fine in park and neutral, no erratic changes in rpms, idles at around 800rpms, idles better when the ecm wire is disconnected from distrutor and stays idle in drive. i dont know what else to check, any input is appreciated.

 

Check IAC counts, desired idle speed, and actual RPMs while the engine is idling, with the EST connected, at idle in Park.

Then do same in Drive.

Report the numbers.

 

how do i check the IAC counts, i am not familiar much with the IAC, your input is greatly appreciated.

 

Scantool. Older general-purpose ones show up on eBay frequently for less than $100, or if you have a laptop w/ serial port you can buy or fab a cable for a bit less...check in the diy-prom forum here for details.

 

since i dont have access to either the scantool or laptop, lets assume the aic works correctly, what else could cause the timing to be way off, and when i say 20 degrees, i am guessing but it looks way more that 20 degrees advanced, may 25 or more. today i started the car and had the timing gun watching it, it stared at 12 of a couple of mintues then it jumped up to the 20+ area and the engined stalled. i hope i am explaining it clearly.

 

You're going to have a tough time diagnosing this without a scanner...