My Delcoed Rides

[vlad01]

lol, careful of the garage wall!

[Holden202T]

Don't you know it!

[antus]

Nice one! I was just waiting for the tyre to start spinning in that last shot

[Holden202T]

I probably would if it didn't have slicks on!

[Holden202T]

So after sorting out some issues and getting it all back together properly i've been finally starting to get into the tune side of things, i have found the happiest sounding idle rpm is 1250rpm, much lower and while it will idle ok it just doesn't sound happy and with the edge orifice lifters i have they arn't supposed to idle much anyways so higher will work better for them. i've also got a big converter so high idle is not an issue.

I now have a 5mm (1mm larger) hole in my butterfly to help with getting the TPS voltage down and still idle at low enough IAC steps.

For me this is the biggest cam i've had to tune on EFI and happy to say that it seems possible to get pretty good idle without needing to use the closed throttle VE table, the map moves a bit so the 5kpa increments in the 70-100kpa area of the map are very handy!

as you can see its idling pretty rich, but thats the happiest point, but its staying pretty constant so thats the main thing!

I have found though that there are some tweaks needed to IAC .... some of the base steps and transitions are not happening quite right so i am going to look into that stuff and see if i can make it a bit more big cam friendly, but in all honesty, its doing a great job considering how far away from its original intention it is working

[Gareth]

So after sorting out some issues

What went wrong?

[vlad01]

Can you list what settings you change to better suit idle with big cams. Mainly the IAC settings

This is something Im trying to get my head around but don't have much knowledge on it.

The issues with idle on Big Gs car makes it hard to sleep at night lol

[Holden202T]

Well main issue was someone left a welsh plug out of the front of the block, so there was only about 5-10psi oil pressure, so had to pull the radiator and timing cover off to fix that, luckily was able to get to it via the cam gear hole, otherwise that was going to mean valve train and cam out, then had a bit of an issue adjusting the tappets, also had to pull the throttle body off to drill the larger hole, then put it all back together!

so far with the idle, i've found lower IAC, ie. 10 steps at idle means even if it does dip revs it will never go low enough to get into that dead zone, so while the idle will drop it wont head down the steep hill of stalling, and usually it gets there before the stall saver can react - this is part of the reason for the hole in the butterfly, also because i have no air bleeds in the manifold like PCV and such it means its way low on air to begin with, and my tps was on 0.94v .....

you also need to watch what it does, i've often found when mine goes to stall it goes way rich, so need to sort out those parts of the table ... ie. 600-800rpm, 90-100kpa etc ..... spots you only ever seen in a stall situation!

also making the timing more stable, as well as VE numbers more flat in the idle area means if it moves around it wont go way rich or such.

i've also found that in park i need about 20 steps, then in reverse it needs almost 80 steps, it gets there but it just takes too long, like it adds a certain amount for in gear but then its not enough and needs to increase.

i also always turn the kill switch off when not using the car so that resets any learned numbers, so i want to try and change what i can so it has less learning to do, its been a long time since i've played with IAC and mostly haven't needed to do too much so going to have to have a look through and some trial and error to get it to where i want.

put it this way though, i could start this at 20 deg water temps and drive it off the trailer within 20 seconds without needing to pedal the throttle, so its not "bad" ... in fact for methanol its unreal, but i do want it to get closer to factory smooth ecu operation just with a choppy idle

[Gareth]

The issues with idle on Big Gs car makes it hard to sleep at night lol

oh for f%&k sake

[Holden202T]

hahaha thats the perfectionist coming out!

so on that note, i've had a bit of a look, few things you can play with.

IAC - Transient IAC params - Stall Saver RPM Threshold - if you have a bigger cam this will probably need to be increased, was 800rpm for mine, i've increased it to 1050 ...(idle is 1250)

IAC - Transient IAC params - Throttle Crack Decay Rate - you can adjust this if you want it to return to idle quicker after a throttle stab.

IAC - Transient IAC params - Stall Recovery Decay Rate - this is how quick it will remove stall saver steps.

if you search for "IAC" there are quite a few different things you can change, but it can also get pretty tricky chasing your tail if you change too much at once!

best thing other than above though is to make sure the tune is good at idle and a bit below and above it, with fuel and spark.