EFI warm up tuning

[CDMBill]

BTW the 'Geek is coming in next Thursday for the swap to to the MS3X so I'd love to see what you've come up with for the 3X.

[Beagle]

BKB, does the IAT in the manifold make it think it's warmer than it is? I moved mine out into the inlet air pipe (other side of the TB) a few years back but it didn't seem to make much difference. My testing was in summer though - the poor engines here never actually cool down. It's 77* here now for instance.

[BKBridges]

Beagle,
My intake is aluminum, but there is a lot of heat soak. Once the motor is started, it seems all the same temp wise. Ive put it in the air cleaner base as well, but Its a PIA when people ask me to remove the air cleaner to see the jewlery. Per Bills post, the 440 has a bigger cam and looser converter (well it did until last week when the converter puked) so I may be cutting it some slack as well. Beagle, What did you do to populate the air temp correction tables in temps youve never seen?
BKB

[CDMBill]

I have the IAT in between the the two TB's an inch or two from the venturi's. I keep the wires and weatherpak long for the base so I can work on it without disconnecting the sensor. I worried about manifold heat soak so that's one of the reason's it's up on the base. The base is aluminum sheet stock we fabricated and gets warm too.

We guessed on out of range baro/IAT/CLT corrections on the low temp side two motor iterations ago and have yet to experience them so we left it alone. On the other hand we've had lots of hot weather experience. I'm not familiar with the BS3 interface so I'm not sure what directly translates.

[dieselgeek]

In megasquirt world, we don't adjust fuel enrichment based on IAT. On the BigStuff3, similar to Megasquirt, the computer is using "Ideal Gas Law" calculations so there should really not even be a table that allows you to adjust enrichment per MAT (manifold absolute temp, aka Intake Air temp), but strangely there is.

There was an old white paper circulating by GM that shows what they use for warmup enrichments, and it's all based on CLT - not on MAT. Some GM systems didn't even have a MA/IAT sensor...!

The BigStuff has this habit of including "some enrichment" in ALL their tables. What I do is zero out the enrichments on both the MAP-AE and MAT enrichment tables. I use only TPS movement for AE (accel enrichment) on the BS3 (and it's siblings). I find it a lot easier to tune this way. So what you end up with is, adjustments in the cranking fuel (BS3 and megasquirt work the same way, they inject fuel in ALL cylinders every trigger event, until the engine is above the crank-to-run RPM). So you end up with a simple table based on CLT, just like megasquirt - it sets the pulsewidth during cranking.

As soon as the engine starts, it's on the fuel map plus any temp-based enrichments, just like MS. I only use CLT temps for enrichments, there's a table in both MS and BS3 for this.

[TheSilverBuick]

MS doesn't use IAT for fuel calcs Even so, I do have my IAT pull a few degrees of timing if the intake temps get to high to ward off pinging, such as when driving in Vegas during the summer.

[dieselgeek]

MS doesn't use IAT for fuel calcs Even so, I do have my IAT pull a few degrees of timing if the intake temps get to high to ward off pinging, such as when driving in Vegas during the summer.

No, MS does use IAT for the idela gas law (look at the gAir field in your logs). It doesn't allow warmup enrichments based on IATs like the BS3 does, however. I don't think I explained that carefully, sorry.

[TheSilverBuick]

Okay that makes sense and explains why some people are asking for it to be a factor for hot starts/heat soak on the msefi forum. On that forum it sounded like a hit or miss problem mostly determined by IAT sensor placement.

[BKBridges]

DG,
I think you cleared a few things up for me BS3 wise! Ive been balancing the transients like a one armed juggler, it made sense but I could never get myself to 0 out the dMAP stuff...The Map vs coolant temp for warm-up is fun to play with too, but its here and gone so quickly Im never sure its right (until it cools down again and goes through the same warmup...)
No knock sensor on BS3, I like the timing removal concept using the IAT, but I dont think BS3 is capable. That would have saved me an embarrasing moment at LV when one of my fans failed in the staging lane. Sounded like a ball peen hammer contest 1/2 way down the track...should have looked at the gages before launching.
BKB

[TheSilverBuick]

They put the IAT timing pull feature in I think for boosted applications so that as intake air temp goes up you can pull timing. It's normally zero'd out but I threw a few degrees at it even though it's N/A. I would be surprised if BS3 couldn't do that for boosted applications.