Lean/Lean tip in when cold

Hey guys, just trying to tweak my cold start stuff and I noticed that I have a very lean tip in (relative to commanded) when the engine is cold. Maf and VVE are dialed in when the car was at operating temp so obviously I don't want to touch them. Once the car is warm this goes away. Would this be a transient issue? Or are there some other temp based tables that I can tweak to try and get actual lambda closer to commanded? I know there are the open loop gain tables but increase that is just going to make my commanded fueling more rich which won't solve my problem. THanks!

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Could try adding a bit to injector tip temp 20deg and below. I've done that before, it ball park works.

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Originally Posted by hjtrbo

Could try adding a bit to injector tip temp 20deg and below. I've done that before, it ball park works.

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Hmm..never thought about doing that. Thanks for tip I'll try that out. Since it is such a short period of time I'm not too worried about trying to get it perfect, but I'd still like to get it a tad closer.

I only looked for a quick second. I wouldnt touch the injector tip tables. OL is going to be adjusted with OL tables. Doesnt matter if commanded matches actual. Its not a closed loop system at the point. Looks like it is super rich tip in with it going lean shortly after. My guess is your transient is already doing too much.

I would adjust your OL IVT tables if there is a lean stumble.

Also to speed up responses, export just the part of the log that has the issue youre trying to identify.

So I noticed this same issue when I adjusted the OL tables when I was having a super rich startup when cold on e85. When I leaned up the OL table I got the lean tip in issue. I richened it backup and found a little balance between the two but have not tried with the IVT table yet.

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Originally Posted by JayRolla

So I noticed this same issue when I adjusted the OL tables when I was having a super rich startup when cold on e85. When I leaned up the OL table I got the lean tip in issue. I richened it backup and found a little balance between the two but have not tried with the IVT table yet.

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One thing I did notice was shortly after re-enabling my prediction coefficients I noticed this. I'm going to go back having them all zeroed out and see what happens because I don't remember seeing this issue with them zero'd

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Originally Posted by ns158sl

I only looked for a quick second. I wouldnt touch the injector tip tables. OL is going to be adjusted with OL tables. Doesnt matter if commanded matches actual. Its not a closed loop system at the point. Looks like it is super rich tip in with it going lean shortly after. My guess is your transient is already doing too much.

I would adjust your OL IVT tables if there is a lean stumble.

Also to speed up responses, export just the part of the log that has the issue youre trying to identify.

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Yeah, I guess I have it ingrained in my brain that I want to see commanded match actual...lol. I'll revisit possibly altering my OL IVT tables

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Originally Posted by sgod1100

Yeah, I guess I have it ingrained in my brain that I want to see commanded match actual...lol. I'll revisit possibly altering my OL IVT tables

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Commanded EQ while in OL should give you around stoich or slightly rich on the wideband. It shouldn't match commanded. While cold you are spraying more fuel than needed cause only the vaporized fuel will burn. The end result should be near stoich

thats what i do with cold OL fueling just make the wideband read .95 - 1.0 fueling and dont worry bout what the command tables are doing to get it there, can even help it warm up quicker too as its not overly rich especially when on ethanol

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Originally Posted by 07GTS

thats what i do with cold OL fueling just make the wideband read .95 - 1.0 fueling and dont worry bout what the command tables are doing to get it there, can even help it warm up quicker too as its not overly rich especially when on ethanol

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So are you just manipulating your OL IVT table to get there?

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Originally Posted by Alvin

Commanded EQ while in OL should give you around stoich or slightly rich on the wideband. It shouldn't match commanded. While cold you are spraying more fuel than needed cause only the vaporized fuel will burn. The end result should be near stoich

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Doesn't if your commanded not match your actual even while cold and in OL your airflow model is off?

Not when cold, re-read what Alvin said, it jogged my memory too. When at normal operating temp, then yes the airflow model is off.

Depending on how your brain works, I find the Ford tables called 'Lost Fuel' and called 'Lost Fuel Decay' a bit easier to understand what's going on. They're high res table's for cold start-up where the unburnt fuel fraction is accounted for. But what those tables achieve is what what the IVT table does, same same but different. Doing what 07GTS said is the go.


https://i.imgur.com/yQXKcKh.png

https://i.imgur.com/Y32NP76.png

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Originally Posted by sgod1100

So are you just manipulating your OL IVT table to get there?

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yes the IVT is good as the rate of temp increase compared to ect can be better to target an area, so a bit of a mix of both the OL fueling and the IVT to get it good works

Appreciate the explanations hjtrbo and 07GTS, I'll mess with my IVT table slightly to try and correct it. Thanks guys!

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Originally Posted by sgod1100

Doesn't if your commanded not match your actual even while cold and in OL your airflow model is off?

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Only the fuel that vaporized will burn.

You've heard of throwing a match in a bucket of fuel? If anything goes off it will be the vapor above the bucket. The liquid fuel won't burn.

This is the situation when cold. Lots of unburned gas going though the engine.

Use the fuel and matches to burn the car down.