VX L67 with 69mm TB Cold start stalling

[Holden202T]

i've just been looking through all the stuff i did back in the VS $51 xdf, it has all the IAC stuff there was defined .....

i am not sure if your VT one is the same or not, ? theres also some tables that might do what you need but not sure if they are really named what you'd expect...

$51 IAC Tables.png (135.93 KiB) Viewed 4005 times

theres also some stuff in the scalars but not sure its going to be off much help ?

[immortality]

I have been looking at those hot idle speeds but I have no idea what they do. Maybe they are named incorrectly?

I've too have come to the conclusion that all the data in that part of the bin has been defined.

[Holden202T]

ok so ....

IAC - Motor Park Position v's Load
This one ... i am not sure how it gets its "load" information, but i'm guessing when the engine is off it will park the IAC at those steps .... probably can work this out with a log as you turn off, see the last IAC setting, and same at key on see where its at.

IAC - Motor Park Position During Crank v's CTS
this one is going to be the one that will help with starting, if you find it starts but then needs to increase IAC to get desired idle, or you need more TPS to get it to go while cranking then increase this table at the desired CTS setting.

IAC - Hot Idle Speed Offset v's CTS
I don't actually understand the numbers in this one, i would have expected them to be reversed, so more rpm increase when cold then down to nothing once warmed up .... but also, its almost like they need another zero on the end, ie. 250 rpm instead of 25 .....

IAC - Runtime to Disable Hot Idle Speed Offset V's CTS
this goes hand in hand with the one above, so it will use the setting of what rpm to change from the above table, this one just dictates the time in seconds that it will remain that high till gradually decreasing to desired idle speed.

from what i've seen in the VS it appears to use more smarts to get idle right rather than a fixed IAC setting it will sort of add/subtract from IAC value to get the idle right and such.

im not sure that it is relevant or not, but when i put the yella terra 70mm TB on my 202 i had to set the idle stop, all good, this was fine till i removed the PCV connection and ran only oil catch can breather lines, with no PCV at all .... did my usual 10-20 steps at warm idle, then i found that it was open too far and causing the computer to drop in and out of idle, as it was seeing TPS % .... turning the idle screw down to fix this meant the IAC was open alot further and it was causing small issues ....

i ended up removing the TB and drilling a 3.5mm hole in the butterfly to effectively give it back that air leak it had, which meant i could have the butterfly closed but effectively allow more air past it! has been working great ever since!

now im not saying this is anything like your issue, but something to keep in mind and also if you do try to drill a butterfly, start small, i worked up to 3.5 over a few trys! its easy to remove and drill bigger, but quite hard to make smaller!

[immortality]

Cheers for all that.

I've been transferring over some of the scalars and there do seem to be some minor changes or maybe I don't have them 100% correct?

ATM, it's not stalling so that is all good. The idle does drop lower then I think it should but that could be related to a possible fuel issue with is showing a lean exhaust code. Hopefully I'll know more about this in a day or 2.

What I did notice is that it did the same thing with the standard TB although not as bad as it is now. I am also off the opinion that the VX does drop the revs quicker after a cold start than the VS does but again without checking/sorting lean code I don't know if this is normal for this vehicle.

I was hoping that changing the decay rate would be a simple way to solve this issue unfortunately it doesn't seem so. Fortunately it's not the end of the world. On a positive note I have learnt a bit more about XDF files etc

I will finish will all the IAC scalars and then post the XDF, hopefully someone can check my work.

[immortality]

I have finished copying over all the IAC scalars, also did the rest of the IAC tables.

What I have found is that it seems the IAC - Hot Idle Speed Offset V's CTS Table is different on the VX.

Still double checking some of the scalars are I'm not 100% on the offsets as some of the numbers seem to be a fair bit off.

[VX L67 Getrag]

This may be where you need to look in hex to see where major changes are, its also where I was talking about searching for bytes before tables in HEX most/if not all that I've used have a search function to look for group of bytes!

[immortality]

Are you using something other than Tunerpro?

I think you have lost me a little here.

I've been using the Graphical table finder to locate the table/scalar offsets.

edit: added my updated XDF. Still not 100% about a few scalars but see what you think. Been using The1s VS V6 v1.22 $51.xdf for comparison.

[VX L67 Getrag]

No need a standalone hex editor I personally have been using HxD 1.7.7.0 just because it's compact & basic/simple but have used hex workshop & ultraedit in the passed!

[Holden202T]

also just be careful what you are copying from, I know when I was looking at n/a ecotec and s/c tunes there would be a big group of stuff all the same offsets, then there would be something specific to s/c only, that then offset the rest of the info by that amount, and so it went on throughout ....

1 byte difference can throw everything out after it! and can make a simple scalar show a number that might look ok, but if its the wrong one changing it can have very un-desired effects.

that why its handy to use hex editors, look at the two tunes side by side and you'll usually see a pattern of the same information in each with the odd offset difference here and there and this can help to re-align the chunks that are the same.

[immortality]

I'm still figuring a lot of this stuff out. I've not really done any programming or looked at hex since I was at tech and that was a very long time ago.

Not planning on changing any of these settings, it's a learning thing as well as trying to populate more of the VX V6 SC xdf.

Fairly much everything (for the IAC stuff anyway) is at a different offset, so I've copied over the XDF parameter, then figured out the offset and then compared the data back to the VS XDF to make sure it matched (most are identical). With tables it's not to hard to figure out, if your one byte off generally the first or last figure in the table will be off compared to the rest of the table I've found anyway.

I do appreciate folks patience and assistance