Tuning Spark w/ EDIS

[zbigtim]

Today I've been working on my ignition timing. For a while I've been living with some serious detonation. At about 4000 to 5500 RPM & Full Throttle, I could here the detonation, then I would pull out of the throttle some, and the knocking would go away. So today I worked on the "upper right" corner of the spark table, and it is MUCH BETTER! It doesn't seem that others have had to back out the timing in this area. Am I on the right track?

 

My engine is a stock L28, w/ a N42 head. MSII code V2.3, w/ EDIS.

 

 

 

 

Thanks,

Tim

[mobythevan]

The timing in your table seems low to me? Have you verified that the timing matches with a light?

[cygnusx1]

Do you really have to pull timing at high RPM's in a N/A motor? I didn't think that was needed. I understand you are getting ping but that might be a separate issue.

[zbigtim]

The timing in your table seems low to me? Have you verified that the timing matches with a light?

 

I verified it by using a timing light with the timing at zero. I set all the bins on and around my idle to zero, and verified zero with the megatune guages. Using my timing light with electronic advance (pictured below), I advanced until the timing mark lined up with zero on the timing scale. I was only two degrees off. So I put a 2 in the trigger wizard. Turned the timing light back to zero and the timing mark was dead nuts on zero. I then re-loaded my spark table.

 

 

Below is a pic of the timing wheel and trigger with the engine at TDC.

 

 

Do you really have to pull timing at high RPM's in a N/A motor? I didn't think that was needed. I understand you are getting ping but that might be a separate issue.

 

I didn't think so either. I first started by taking the map and scaling by .78, when that didn't work I pulled timing in the problem area.

 

Is it possible I'm too lean up there? I haven't done any tuning in that area, afraid of blowing a hole in a piston. Now with the knocking almost gone, I can datalog and see. Maybe tomorrow...

 

Thank you,

Tim.

[mobythevan]

Your AFR table looks good, but how much authority does it have? Maybe it is running lean and can't correct enough because the VE table is too far off.

[cygnusx1]

Good point Moby. The AFR table is totally fictitious if the VE table can't fill the bill. Add some fuel up there and bring back your timing.

[zbigtim]

Thanks for the reply guys. Tonight I datalogged and found that the engine is running a little lean up there.

 

This pic shows my AFR running 13.3 @ 5500 RPM, on a hard acceleration.

 

After running the VE analyzer:

 

Maybe I just need to run a few datalogs and tune.

 

Moby, to answer your question, I have the authority set at +/- 15%. Should I set that to 0% for tuning? I think I would want the VE table to get me darn close to my target AFR without correction. Then set the authority back after I'm satisfied with the VE table.

 

Tim.

[mobythevan]

There are a few ways to get the VE tuned in. I usually turn off AFR correction and get the table closer by driving around and tuning by hand.