olds 350 on ecm

[90hurst/oldsguy]

i have an olds 350 running on a 84 hurst/olds ecm. everytime we try to advance the timing it moves back a degree or 2. Can anyone help me understand how to fix this problem, or what to do... i have it on there for trans to lock up, with a vacuum advance distributor it did the same thing.

 

[littlerascle59]

Their was a guy on here or Oldspower that was running a 403 on the factory ECM. Hopefully he'll chime in on this for ya. I kinda wish their were more research in modify the stock ECMs to support different engine/trans combos.

 

[DoubleV]

What exactly do you mean by 'it moves back a degree or 2'? Do you mean you have the distributor loosend, turn it so you have your base timing set ( should be 20* with the ECM disabled ), then when you tighten the clamp down on the distributor it moves a little? If so, that happens all the time. It's really not that hard to get right, you just need to play with it to get it. in your case, it seems you can just set the timing to about 22, then when you clamp it down it will move a little and be right at 20.

And you know you can't run a vacuum advance distributor on a car on the ECM right?

Lastly what do you mean by 'I have it on there for trans to lock-up'? If you're saying you're running on the ECM soley for the purpose of transmission lockup and aren't running with the proper CCC carb/distributor, then no, that will not work at all.

Be more specific and tell us exactly how your engine/ECM is set-up. I have a feeling it ain't set-up right and if that's true then we can tell you how to fix it.

 

[90hurst/oldsguy]

the engine has rv torque cam in it and with #6 heads. the distributor has the harness for the ecm (not vacuum advance). the ecm is the factory hurst/olds ecm so nothing special at all on that part.
with the timing set at 20 degrees it run and starts fine and doesnt hesesitate to start back up.

As I adjust the timing and have set and have it tighten down then it moves back 2 degrees. yes double v your right. then timing is past 22 degrees then its hard to start.
I have the plastic timing tabs that come on the g-body. do you have to set the timing with ecm disconnected first.

 

[DoubleV]

the engine has rv torque cam in it and with #6 heads. the distributor has the harness for the ecm (not vacuum advance). the ecm is the factory hurst/olds ecm so nothing special at all on that part.
with the timing set at 20 degrees it run and starts fine and doesnt hesesitate to start back up.

As I adjust the timing and have set and have it tighten down then it moves back 2 degrees. yes double v your right. then timing is past 22 degrees then its hard to start.
I have the plastic timing tabs that come on the g-body. do you have to set the timing with ecm disconnected first.

Advancing the timing a couple degrees is a common 'hop up' and shouldn't in any way make your car hard to start but Yeah, when setting your base timing you MUST disable the ECM by grounding the A and B terminals of the ALDL or you can unplug the 4 wire harness that goes to the distributor. Without doing this, it would be the equivalent of setting your timing with the vacuum advance still connected ( to full manifold vacuum ) on an old school non CCC setup. It would be WAY off.

 

[90hurst/oldsguy]

I think i got what you are saying. If you dont disconnect the ecm it will make the car seem like it is not timed right.

i also notice that i cant really feel torque converter lockup either. this is really helpful to know.

 

[DoubleV]

I think i got what you are saying. If you dont disconnect the ecm it will make the car seem like it is not timed right.

Pretty much. If you tried setting your base timing ( to the stock 20* ) and didn't disable the computer ( or unplug the distributor connector ), your base timing would end up far lower than what it should be.

i also notice that i cant really feel torque converter lockup either. this is really helpful to know.

I never noticed much of a difference with mine either.