tip in spark retard aka Transient Ignition Retard

[techsalvager]

I take it theres no way to retard spark by TPS?

[Peter Florance]

I take it theres no way to retard spark by TPS?

Idle advance?

[techsalvager]

checked there but I don't see anything that can help with pulling spark out per tps %
like if I shift and go wot again.

[Peter Florance]

checked there but I don't see anything that can help with pulling spark out per tps %
like if I shift and go wot again.

Sorry but tip-in didn't give me a lot to go on as far as what you are trying to do.
Exactly what do you want to happen and when?

[techsalvager]

here is it out of a help file for another ecu tuning software

" The Transient Ignition Retard function is designed to introduce ignition retard during transient conditions. Transient conditions are identified by a fast change in Throttle Position (TPS) or Manifold Absolute Pressure (MAP). Ignition is retarded depending on the rate of change of TPS or MAP, then held retarded for a particular number of engine cycles.



Transient ignition retard can be used to eliminate 'snap detonation' by retarding ignition timing when engine load suddenly changes"

[Peter Florance]

here is it out of a help file for another ecu tuning software

" The Transient Ignition Retard function is designed to introduce ignition retard during transient conditions. Transient conditions are identified by a fast change in Throttle Position (TPS) or Manifold Absolute Pressure (MAP). Ignition is retarded depending on the rate of change of TPS or MAP, then held retarded for a particular number of engine cycles.



Transient ignition retard can be used to eliminate 'snap detonation' by retarding ignition timing when engine load suddenly changes"

I've never needed that; I wonder if MS does a better job of load update to the spark subsystem so the timing stays optimal?

Not seen that feature in MS but maybe someone else has and I've missed it.

[techsalvager]

here is it out of a help file for another ecu tuning software

" The Transient Ignition Retard function is designed to introduce ignition retard during transient conditions. Transient conditions are identified by a fast change in Throttle Position (TPS) or Manifold Absolute Pressure (MAP). Ignition is retarded depending on the rate of change of TPS or MAP, then held retarded for a particular number of engine cycles.



Transient ignition retard can be used to eliminate 'snap detonation' by retarding ignition timing when engine load suddenly changes"

I've never needed that; I wonder if MS does a better job of load update to the spark subsystem so the timing stays optimal?

Not seen that feature in MS but maybe someone else has and I've missed it.

I doubt it in terms of optimal updating.

this issue is when you go from say 39 degrees to 21 degrees in your map and det occurs.

and considering all the oem ecu's including newer ones have it, speed density and or maf based systems I don't think its an issue of if your timing system is good or not.

[Peter Florance]

Possibly you should edit your post title to "Transient Ignition Retard "

[dieselgeek]

I can't understand why this would be needed?

[Peter Florance]

I can't understand why this would be needed?

Looks like Link and some OEM Siemens ECU's have it based on a quick Google search (why updating the thread title is a better idea)

[dieselgeek]

I'm looking for "application" reasons why someone would need this. "Because the other guys have it" is a crappy reason. Try tuning a Link ECU on a roadracing car - the last thing you'll be concerned about is TPS spark control. I promise.

[techsalvager]

snap det as well as for ease on autos trannys

[Peter Florance]

googling the term "Snap Detonation" yields almost no hits. It must have another name?

[dieselgeek]

snap det as well as for ease on autos trannys

Auto trans shifts at WOT, torque management needs to be done another way, and until Motec does it - I'd consider it a lot less important than other features in queue.

What is "snap det?"

-Scott

[Matt Cramer]

I think he's saying it pings on immediate throttle opening.

[Peter Florance]

I think he's saying it pings on immediate throttle opening.

Is there a theoretical explanation for this? Nothing in Heywood that I could find

[Matt Cramer]

I think he's saying it pings on immediate throttle opening.

Is there a theoretical explanation for this? Nothing in Heywood that I could find

If I were to take two guesses:

1. Running through a spark table point that's not tuned right
2. Transient lean spike from needing to tune VE or AE

[billr]

Or maybe a MAP sensor that is located or filtered such that it is responding too slow.

[muythaibxr]

I think what he's saying is that when you are at steady state and low load, you might be at say 35-40 degrees. Then you stomp it... well you're based on speed density... We measure actual pressure in the manifold, so by the time you do the lookup for the spark table and get the new timing scheduled, a couple of spark events may have already happened at a timing that's higher than what you wanted. He wants to retard the timing based on TPSdot or MAPdot to account for the fact that we might be a few spark events behind on a quick stomp.

I would say this should be a non-issue as long as you have everything else tuned correctly. For example, if you're using "50" for your lag filter value, figure out why you need it that low, and fix that, then change the lag filter to 100. That will get the table lookup more inline with the actual engine conditions.

Once we schedule a spark event, if the tooth it's scheduled from changes, we don't update that event... it happens then we schedule the next one, so if you could go from high timing (35-40 degrees) to a lower timing (20ish) in the time between spark events (very small, especially at revs higher than idle), you might be able to cause a problem. However, there's no real way to solve this one.

Ken

[Peter Florance]

Once we schedule a spark event, if the tooth it's scheduled from changes, we don't update that event... it happens then we schedule the next one, so if you could go from high timing (35-40 degrees) to a lower timing (20ish) in the time between spark events (very small, especially at revs higher than idle), you might be able to cause a problem. However, there's no real way to solve this one.

Ken

Ken,
Do you think the manifold can fill that quickly?

so far seems like non-issue to me.