IGNidleADD ?

[secure]

I have been wondering why IGNidleADD retards 16 degrees of timing at idle? Engine suddenly stalls at idle .
Which map is this? Couldn't find it in abbreviations. I have zerod all but still retarding idle igntion



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[pat]

secure,

The reason for the idle ignition adder (subtracter in this case I guess ) is that it allows the ignition base map to remain at MBT timing, whilst dropping the effective thermal efficiency in the idle state. This is done to allow a rapid response to a load, ie the air and the fuel are already in there, all that is needed for a torque burst in reaction to a load change is for the timing to be advanced again.

You can get rid of this additional retard if you can achieve load regulation a better way by altering the Idle Control -> Closed Loop -> Base Idle Ignition Adder table. I would say though, that trying to react to a load change by means of the TBV is likely to make the situation worse since there is no TFC for TBV changes, and although there is for DBW changes, the delay in the change in plenum conditions that result would result in poorer load regulation.

Hope this helps,

Pat.

[secure]

Thanks Pat. I got it.
2-3 degrees of timing may be to low for my car.
Engine idles very stable with 850cc side feeds but sometimes engine suddenly stalls at idle. I doubt it may be related with very low ignition. I will sort it out.

[pavlo]

What you may be missing is the: Idle Control->Closed Loop->Base Idle Ignition adder which will subtract a fixed amount of timing from the base ignition map based on Ect and RunTime. So this means you can get a nice strong idle when cold and after startup when warm, but when hot and runtime is higher you might choose to retard the base ign by say 10degs. This table is also useful for regulating the speed after start when hot.

The total retard will be the above table PLUS the Idle Control->Closed Loop->Proportional Ignition Adder which is why you might be getting a large amount of retard when you drop into idle.

With these two tables in use, you should not have your desired idle ignition value present in the base ignition table. you can easily run it flat at around 25 degrees if you want, which makes for much snappier throttle response out of idle as the ignition goes from bring the speed down (with high idle valve opening) to helping it stay up as the throttle goes past the threshold for closed loop idle (typically 1% above rest Tps1). So you would not use a "timing hole" with these tables, especially as the Proportional Idle Ignition is relative to idle error, so when you want your target idle to be say 1500rpm just after a cold start, a timing hole approach will leave you with very little timing as the hole is always based around the hot idle speed.

You can experiment with the Proportional Idle Ignition table, and you may also find that at high positive errors (so 500 above idle target for example) you don't want to retard the timing as much as it can cause the idle to drop too quickly.

[secure]

Very helpful post thanks Blamire!
Advancing the base ignition is a good idea. Honestly it didn't come to my mind. I just focused on idle ignition tables!