Bridging fueling for Heatsoaked Restarts to Wideband/Closed Loop zone

[atlex]

Just sharing something I've come up with to solve a particular condition I've seen.

 

I've had a scenario where I get quite a lot of heatsoak and my injectors seem to open too slowly(or something, but I did see some data on this condition on another forum) to fuel correctly so I see a lean condition for up to a minute as fuel flow cools them down again. My IAT sensor is close to the injectors so we can use that number as a factor..

 

I recognise a suitable closed loop solves this after the wideband is sending real data but I didn't want to run adhoc fuel corrections for IAT since those are permanent and where I live the air can actually be quite hot. And a wideband can't give adequate fuel info until it finishes warming up.. this leads us to the post-start configuration..

 

I've ended up with a 3d table for post-start where it's X ect and Y iat - similar to a regular post-start 2d table but with the higher IAT area seeing up to 35% more fuel put in - say 30c IAT 10% more fuel, 40c IAT 20% more fuel, 50c IAT 30% more, up to 35% at 60 IAT

 

Closed loop set to come on after 25 seconds, post start hold time 25 seconds with a 5 second decay.

 

[Confused]

I think something similar is applied in the 350Z base map, this is a Modelled Mode setup, where IAT Trim is usually disabled, but due to the heat soak, they use the IAT compensation too.

 

But always useful to see different approaches to issues like this  

[Adamw]

I usually just put engine runtime on one axis of the IAT table for this type of correction in the past.  At high IAT's add xfuel for xSeconds then fade it out over xSeconds.  I think your post start table would do pretty much the same thing.  

[essb00]

I thought I'm overdoing it. It turns out it is really needed, huh? 

IAT reaches over 70°C in this tropical summer day time.

[0x33]

I do something similar using charge temps and varied post hold times/decays. helps massively with heat soak starts, so you are thinking along the right lines

[atlex]

On 3/24/2023 at 2:17 AM, Adamw said:

I usually just put engine runtime on one axis of the IAT table for this type of correction in the past.  At high IAT's add xfuel for xSeconds then fade it out over xSeconds.  I think your post start table would do pretty much the same thing.  

I started thinking about this setup when a friend showed me a post of one of the actual experts here (you or Andrei?) saying that the IAT fuel correction table shouldn't be used in modeled mode. I'm guessing the modeled mode is designed to use an ideal gas law internal table...

Previously my solution was to roll an IAT fuel correction table with a TPS Y axis to help boost the lower TPS zones going lean for hot start and hope that with driving the IAT came down again, but I knew that just wouldn't cut it in summer and will absolutely mess with any closed loop stuff LTT stuff which honestly handles this far more cleanly heh.