Thread: Idle timing table VS Main timing table....Dave or John?

Is the idle timing table related to the main timing table?

I just recently went from BC2 cams to BC3 cams and wanted to try a few things. I wanted to raise the idle timing from 15 to 20-25deg to help obtain that higher idle easier and for ease of checking timing with a light.

I know whatever values in your idle timing table your distributor must match each other.

If i try 25 from 15deg does this add an additional 10deg of timing to my main timing map or are the tables totally seperate?

Thanks

These tables are totally separate.

The idle timing table is only active when the "Idle Timing" checkbox on the data screen is checked. The idle timing table is the value the engine will use as the timing value (+/-) idle error corrections and any warmup advance you have going on.

To verify this, check the final ignition value data item in the data list or gauge window!

As soon as you get the engine "off idle", it will un-check that box and will then move onto the main timing map.

John,

What about the old sckool method of advancing your distributor ignition timing? example: for a sr20 you would advance timing from 15 to 19/20deg.

The correlation between the "idle timing table" and dist timing would not be correct and a 5deg difference.

How does this make power then? Aren't you effectivly adding 5deg across the "main timing table"?

I just want to make sure that im not adding 10deg across my main timing table if i do the JWT trick of running a higher timing in the "idle timing table"

I will also double check under nismotronic/nissan datascan

Yes, that is exactly the idea.
How does this make power?
I'll leave that up to the reader to figure out.




However on a properly tune-able solution like Tunercode, you have absolutely no reason to do this "trick".

Right now i have my idle timing table left stock at 15deg across the table. My dist timing also matches that table at 15deg. All my adjustments have been made on the main timing table of course

Im having trouble with my car stalling at a stop and when i have it in timing mode to set idle and timing my idle screw is all the way out now.

I see that JWT ecu's run 20 or 25deg in the idle timing table. I was going to give this a try. Since my main timing table is already setup how id like. Do i need to subtract 10deg across my main timing map?

I was just trying to compare this to how the old school method of advancing your timing (like if u have a stock ecu) works.
Is this because there is 5deg difference in correlation between the 2 tables with that old method of advancing timing VS no difference in the idle timing table and dist timing of what i want to do now?

My old JWT ECU had a 25* base idle ignition timing.

It makes the cams ultra smooth and A/C kick ass when it is in operation and I saw better mileage than what I get with my stock ECU that I swapped back in and turned back on the SAFC II settings.

Go figure. It worked, it was a great idea and implementation Clark from JWT did.

Don't confuse idle ignition timing tables with the ignition timing recommended/used to set your distributor orientation. They are different things. Or they should be. The post below mine says otherwise?

When you place your ride in timing mode, if you change that Idle timing table to 25* you will have to match up your Distro to 25* mechanical timing.

and dont modify your ignition Timing map as then you will have created an unwanted offset, those maps work when the TPS indicates the TB is opened.

ok gotcha guys. I might try the 25deg timing at idle to see how and if it improves the big cam idle.


Im still stumped on the classic thing of advancing timing, like if you had stock car? if you advance the distro from 15 to 19. how does the timing change on the main timing table if your saying the idle timing and main timing are not related?

If you move the distributor ahead 4 degrees for ignition timing, then that is the same as adding 4 degrees TO EVERY SINGLE MENTION OF IGNITION TIMING in the ECU EVERYWHERE.

Anything that has anything to do with timing will now result in 4 degrees MORE than requested by the ECU. You are basically taking what the ECU is ultimately requesting for ignition timing and advancing that by 4 degrees, making it happen 4 degrees sooner than expected. Always and forever for everything.



That is different from using a tune-able ECU and changing idle timing alone. Or main timing alone and based on TP and RPM. Or anything else timing related such as knock-based retard, etc.