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Zero demand ignition table

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Hi all, I'm new to efi tuning and I'm currently mid way through some courses.

I have a haltech elite 2500 and went for a drive yesterday on just a base map but was playing around with the data logger.

On reviewing the data I noticed at a point just after accelerating that I was in the cell on my ignition map which was about 22 degrees, however the actual timing was at 32 degrees, I've worked out that it's because of the zero demand correction but I was a little concerned that I was still showing positive boost when this occurred.

What should I do with the zero demand table?

Do I need to use it or just rely on the idle timing in my base map?

Please help as I'm in way over my head and still learning.

Please see the attached screenshots.


Attached Files


Attached Files

The zero demand table isn't a correction, it's the timing you will be running whenever the tps is essentially at 0% or at least below your minimum user demand limit as set up in the main engine setup page, say 1 or 2 percent.

Definitely don't need to use the zero demand table, it's there as an option that may be beneficial to some? For some reason every base map comes with it enabled for ignition and I found it to be a little confusing at first too, I prefer to use the base ignition table so I unchecked the box under the ignition tab in engine setup.

Thanks so much for the reply! If I uncheck the box will it still idle? I presume it will just run on the base ignition table?


I removed the fuel version from someone's 13bt a couple of years ago, I really can't see the point in 99% of cases for using anything other than the main fuel & ignition tables, even if they are tps×map.

Your timing around idle looks decent on the base ignition table so you should expect it to idle just fine, keep going with the course material as there's a few things that stick out in your pic.. Like more load sites than you'll likely ever need in vacuum, at 53% tps the zero demand table won't be in effect so there is another correction being applied that is advancing your timing an extra 10 degrees, definitely want to figure out what's causing that. I'd still ditch the zero demand table for simplicity.

Michael, what was the idle like with zero demand on for fuel? It'd be hard to maintain a steady afr wouldn't it?

Yeah it was hopeless. Maybe if you were trying to dodge up an ITB turbo system with MAP only tune you might try it but I imagine a vac manifold would be better anyway.

The shop that did it hadn't set up the bypass either, ended up stabilising idle by shaping the ignition map, another think a zero load table won't do.

I think the zero load maps are a hangover from the earlier Haltech ECUs. I've never used them and as stated by others, you should be fine to just disable them.

Thanks everyone, I have disabled the table.

Running just fine.

Thanks again cheers.

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