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Old 08-04-2005, 04:44 PM   #1
QWKSNKE
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EECV timing explained

Another quote from boss96. Bob I hope you don't mind

Quote:
This is a general explanation of how timing is done on a eecv. Not comprehensive but it should get you going.
There are 4 main spark tables used.
MBT spark--Maximum brake tq
Alt spark--spark used at high altitudes
Bdln spark--Borderline spark, also known as max allowable spark
Base spark--just as the name suggests

There are also modifiers to the spark tables based an iat (inlet air temp), ect (engine coolant temp), imrc (used on a 4v motor, a spark adder when the imrc plates open) base and bdln adders for a/f ratio(an adder for more spark as a/f goes richer).

The main thing to remember is the eec will look at all the spark tables and use the lowest spark value.

Most timing values used in normal driving come from the bdln tables. The bdln table values are the spark settings that will keep the motor from detonating (pinging) when running in CL (closed loop fuel control) and an iat temp of 70 degrees. The bdln spark values are therefore lower than the values found in the base and mbt tables. Spark is added to the bdln values under high load and lower a/f ratios which can be seen by looking at the "spk bdln add a/f" table. The motor can usually tolerate more spark advance when running a richer a/f ratio.

"Spk bldn retard for iat" is a table or function that retards timing as iat temps go up. On most eec's the timing retard/advance is zero at 100 degrees iat. Below 100 degrees iat the spark is advanced to some extent.
Above 100 degrees timing starts to get retarded. The values in the table are big, for instance, at 140 degrees iat the value is -46. This does not mean that timing is retarded by 46 degrees. The number is multiplied by the values in a table/function called "spk bdln retard act multiplier" which contains values that are low, in this case around .1 for the higher load/rpm values. Multiplying -4.6x.1 gives you a spark retard value of -4.6, so you have 4.6 degrees of timing retard being applied to the spark values in the bdln table at those particular rpm/load values.
Same logic goes for the "spk retard for ect" tables but the values in this table are not so aggressive as changes in ect do not effect the tendency for detonation as much as iat temps.
So, in the above example you could determine how much spark the motor will see at a particular rpm/load by looking at the adders and bdln tables for that engine range taking into account the ect and iat temps and the a/f ratio you are commanding at that time. If you have a 4v (cobra) then you would also look at the amount of spark that is added for when the imrc plates open.
Now for the other tables. Not to be taken as gospel but this is how it was explained to me and it does seem to work this way in real life.

MBT spark-Like said above, this is the spark values that Ford determined will make the most power for that particular motor. On a STOCK motor, advancing the timing beyond these values will not increase hp. This table is used more or less as a "reference" table of values, not really used in normal operation.

Base spark-Similar to MBT in that it is used as a reference table for the eec to compare the other spark tables to and then choose the lowest values. If for instance at a certain rpm/load value the spark commanded from the total spark values from the bdln table plus any adders is higher than the spark commanded in the base table at that rpm/load then the eec would allow that spark to be used, it would look at the base tables lower value. However, you would also need to look at "spk base add a/f ratio" to see if any spark is added to the base values during richer a/f ratios also.
Altitude spark- I'm sorry to say I'm not clear when this table is used by the eec, presumably when higher altitudes are seen by the maf then they are used. Since I don't live in a high altitude area I have not noticed it being used that I can tell.

As far as how to use this info to set your spark...it's up to you. Many people will simply datalog their spark values and add/retard spark through the bdln tables to arrive at the spark that they want and leave the other tables alone.
If you want to simplify things you can disable some of the tables so you are only using one spark table. The way to do this is to input "55" for all rows/columns in the tables you don't want to use. Remember, the eec will choose the lowest spark values from all the tables so having 55 in the base table for instance means that those values will never be used.
I can use my car as an example. It has a supercharger and I want to set the spark relatively low for safe operation.
In my case I want to use the bdln table for spark control so I can also relocate the iat sensor in the discharge side of the supercharger. By doing this I can retard timing by using the "spk act retard" table so as discharge temps go up from the blower my timing will go down. I disable the ALT, MBT tables by setting them to 55. I also remove any spark adder values from the "base/bdln add a/f" tables by setting them to 0. The base table is set to the same values as I have in the bdln table.
Now I can set my spark to whatever I want and that is what they will be. I also have spark retard for iat/act temps so if the weather is cooler then I will have a little more spark advance and more power. Hotter weather means the spark will be retarded and therefore "safer", compared to using a fixed spark value. Another benefit is if you were to use water injection you could see increased power from the lower iat's but if the water inj. fails you would simply see less timing and not damage anything.
Bob
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Old 08-06-2005, 09:57 AM   #2
boss96
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Re: EECV timing explained

No problem, thanks for posting it. I hope it is not too complicated and helps people out.
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Old 09-03-2005, 06:03 AM   #3
sailorbob
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Re: EECV timing explained

My observations on the BASE and ALTITUDE spark tables are that from the eec-iv codes I've seen on MAF equipped cars the two tables appear to be a hang over from the pre MAF and very early MAF equipped cars that still ran BAP sensors. The code for the base spark calculation interpolates between the two tables according to barometric pressure. Now on later MAF cars the BAP sensor was dropped because there is no need for it and Ford set the tables to the same values in virtually all of the cells (I've only seen the odd couple of cells that differ in most codes and these typically only by 0.25 degrees). For tuning purposes both tables should be altered and set to the same value to avoid the interpolation shifting away from what we desire (or causing us to enter a false value to compensate).

For normally aspirated tuning, as an alternative to having to update both tables, I change the address of the ALTITUDE table within the spark table lookup routine to point to the BASE table, this means I can zero the values in the ALTITUDE table and ignore it.
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Old 09-03-2005, 06:20 PM   #4
Dale McPeters
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Re: EECV timing explained

sailorbob,

This would not be a good idea on the later model EEC-V cars that are running a blower or turbo setup........something lets say like the '03-'04 Mach 1's etc.
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Old 09-06-2005, 10:31 AM   #5
sailorbob
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Re: EECV timing explained

Thanks Dale, could you enlighten me further, I must admit I don't know much about how the eec handles forced induction. My post is aimed at normally aspirated tuning and to try to clarify the function of the altitude spark table, I've edited my post to suit.
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