What do the numbers in AE - AE Temperature factor vs Coolant Temp mean? Holden 355 with dual plane running leanwhen cold

[Mr DOHC]

I’m having a cold running issue where when I accelerate within a few mins of starting the car leans out and runs shit. I assume the coolant AE is what needs to be updated. But what do the numbers mean, they don’t seem to be multiplier's as they’re less than 1 of.

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[antus]

There are also other cold engine enrichment tables, it could be they need to be reduced and your overall injector rate turned up. tune for hot engine first, then look at cold start params to dial that in knowing the basic parameters are right for a hot engine. If its good when cold and bad when hot, then there are probably general tune problems and the warmup enrichment is also wrong but two wrongs are making a right only when its cold. The settings I am thinking of are to do with warmup enrichment, delay. Search to find the right entries.

[Mr DOHC]

Oh it’s beautiful once warm. Just those first few mins when cold.

[Mr DOHC]

What are the best parameters to alter for cold start running?
When it’s low in the revs and throttle and very cold it goes to 18:1 and labours hard. If I need to get across an intersection quickly and I give it half throttle when couldn’t really picks up and goes though.

It’s that cruising around when cold that’s 95% the issue.

[antus]

I havn't needed to change this on my car but maybe try these two? I thought there were others, at least a scalar that enriches for the first minute 20 or so of cold start but I cant find them now so maybe its other operating systems. My thinking is the airflow and the injection doesn't change when cold, but the fuel atomisation does. So if you increase the cold AFRs then you'll inject more fuel when cold to compensate. If anyone has better ideas or a table I've missed, let us know.

Also search warmup. There are a couple of IAC options to add more air when cold.

[vlad01]

AE vs RPM table is for AE at each of the given RPM starting points, eg. Holding steady at 2500 rpm and then stabbing the throttle, if it has a stumble at that RPM starting point but no others on that table, you adjust that one, either less or more. The WB can trick you, lean spikes are usually a given, and sometimes it might not actually be lean but rich instead, a very rich condition can cause a misfire (like a stumble) and that reads lean since it has not actually burned and consumed the oxygen.

Very often I found reducing AE removed stumble more often than adding it, especially at low rpm. The WB wasn't very indicative of what was going on, and almost always showed some sort of delayed lean spike.


The AE temp multiplier table does exactly that. It multiplies the whole AE vs RPM table by a factor against a temp ref.

1.5 means its 150% and 0.25 means 25% of the normal value.

This table is little harder to use as it doesn't tell you if its a certain RPM like the other table or the temp, or a combo of both. I start with the normal AE table on a known temp, like full operating temp where its steady, sounds like you already dialed it in.

Then let the engine cool overnight, start, then start checking throttle stabs at each temp cell as the engine warms up, adjust each as quick as you can, save, move on to the next temp as it heats up, adjust, save etc... It's becoming a good time of the year to do this as it's going towards winter and the colder it gets at night, the better range of tuning you can cover for the warmup and associated settings.

It may take a few days to get enough warm up cycles to dial it it. If you run the emulator, you can update the ECU quickly, rather than uploading the whole tune for each adjustment. Assume nothing, and try adjusting both ways for each cell's temp. Like the AE, the WB numbers are deceiving at times, especially transients.



Also look out for this one, it really gets everyone including me, messes with warmup stability and pretty much stalls most worked engine abruptly as it warms up from cold.


I zero it out, so at 44c, it doesn't jump from warmup tables to main AFR table and back, which causes the fueling to go to 14.7 for 20 sec or whatever the default is at exactly 44c and back to idle/warmup tables after. When this delay setting is zeroed or reduced to something like 1 sec, it skips the hold at the main table and goes straight to idle tables as soon as you close the throttle, it also stops it spontaneously switching to the main table on this 44c transition point in the function. Does that make sense? It didn't for me either when I and 202 worked it out some 10+ years ago.



The screen shot shows the settings, one for park and one for drive/manual box. The other temp one is just to show that the transition happens at 44c, leave this setting alone. It enables the normal use of the main AFR table and switches away from the cold engine tables once the engine hits 44 and above, it's just the delay settings that mess with warmup and idle, especially bigger cams.

You could potentially increase the temp setting, so that the engine remained in warm up mode for longer, giving the engine more time to stick to richer warm up tables. I normally just remove or heavily reduce the delay as I feel its more of an idle speed and AFR mismatch caused by the excessive delay. Likely set in the factory for best emissions.

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