Ok fellas, I am somewhat new to crome but not new to the tuning scene. Most of the time (in distributor equiped cars) when you increase the ignition timing it will increase hp by starting the power stroke sooner... but when I am looking at the base map of my P28 here in crome I see that in some instances the spark timing is actually a negative number. If I were to just select all and increase by a 10% increment it would not have the same effect as with the fuel tables. Does anyone have a beginner/intermediate guide to using crome or have any advice on how to adjust the spark tables for more power? Thanks

 

on the dyno.

 

http://www.xenocron.com/install/CromeGuide.htm

 

why would you ever want a percentage of ignition? Fuel is understandable. I have never heard anyone talk about saying I added 10% ignition and it picked up xxx power. There is a reason for that. You bump your ignition by a set number whether it be 0.5 degress or whole numbers. This is why Crome wont let you use % to bump your ignition. Put the car on a dyno and set the ignition. Dont ask why you cant do it this way or that, just put it on the dyno and finish the car.

 

you should down load some of the domestic car tuning stuff that maybe how it works. i tried to tune a guys 350 with my moates burner and some software off of moates site that thing was hard to tune and understand.

 

I dont know what version of crome you are using but in 1.5.0 you can use the "Adjust Selection" button to adjust spark tables with the % just as the fuel tables.

I understand what you are saying about doing it in degrees just like on a distributor V8 engine with a timing light, but I guess my main question was what to do about the negative numbers that appear at little to no vac at low rpms?

Do these numbers in the spark tables show what the ecu is adding or subtracting from the base timing or what the actual timing numbers are for the specified rpm and vac?

If it is what is being added or subtracted, how can I find my base timing?

Can I loosen and rotate the distributor like in a V8 to adjust the base timing?

Can I use a timing light to find and set the base timing when doing this?

Has anyone had problems messing with the spark tables?

Has anyone adjusted the spark tables using crome while the car was on a dyno and what kind of numbers were seen by doing this?

Sorry about the long post, feel free to answer to any question, thanks

 

THis is very simple, and again, I am not really concerned with what John added to his "newest" version of Crome. The reason there are negative numbers in the timing tables is simply because that is what it would take to run the engine if you could ever get the engine to run in that portion of the map. To set timing, you will get the car warmed up to at least 170ish and make sure no load on the car ( no fans, headlights, big giant subwoofers) and see what the table says you are idling at. You will now put a jumper in the service connector and walk out to the engine and set the timing to what you see in the table so they are now sync'd. You will then drive to the dyno and place the car on the dyno and tune the table with real numbers and not %'s of a number. You will know exactly what the timing is becuase what you have on the table is what it will be at the engine now that you sync'd it from the beginning ( as long as you dont have any other corrections affecting the ignition like ECT comp or IAT comp) Your car is now done and again will only take at max 2 hours.

Now to answer your questions you asked:
Nothing
Only actual once timing is syncd with dizzy
Base timing can only be found by syncing or mathmatically finding it once you determine if the software will be the master or the engine will be the amster for the base number.
Yes.
No.
Yes. An increase or decrease in power and torque as it should be expected.

 

FYI I'm not a tuner but I enjoy reading and learning as much as I can about calibrating EFI with the use of modern day editors.

To answer your question they show a represented value of advance or retard most typically above the base timing (14-16 deg typically) where your cruise-WOT driving conditions lye but their are values below the base in some regions of the table for acceleration and even negative values in high-load/low-rpm for the occasion you decide to have a car load of people or you decide to tow a small water craft under hard acceleration.

As far as other factors, you have your ECT & IAT correction factors in "Edit Advanced Tables" section or icon that allows you to edit modifier values that apply to existing table values for ignition timing + fuel depending on engine temp + intake manifold air temps at any given time. These functions work to add or subtract a few degrees from the tables represented values under any give load/rpm when say before the engine warms up to full operating temp (adds advance to the table value typically) or say when an engine experiences higher than normal temps (then it subtracts timing from the given table value).

What was mentioned mainly describes the ECT correction role however the same applies to IAT factors under various conditions as well as fuel corrections like mentioned that adds or subtracts fuel to the fuel table values under various temperatures for coolant and intake air temps also.


Reffer to below

Yes, but follow advice below or the manuals procedure with the engine fully warmed up at idle with service connector jumped.

Yes

Follow TurboChurch's advice

Just set the base to 14-16 BTDC (like stock) or 0%throttle (assuming no vac leaks) at idle speed (usually 750-900)