Bigger cam problems!

[VX L67 Getrag]

Hey all,

1st go at trying to tune a cam install & have it all sweet except for when coming to an intersection if I pull up slowly it almost stalls but just catches, but if I stop in a reasonably normal speed it stalls & sudden stop no chance!

I'm guessing there must be an iac affective area or a decreasing air mass used to catch this or something?

Any ideas? My fuel trims are within 1%

Cheers VX L67 Getrag

EDIT: I have also narrowed the narrow band ranges to try & ease the dilution with overlap, but still not a happy idle catcher!

[Jayme]

what iac steps does it idle at? you might be able to help it by opening up the tb a bit?

[darcy]

Try lifting the "DESIRED IDLE AIR RATE VS RPM - xxxxxxx" for each gear.

[VX L67 Getrag]

Yeah thanks Jayme & Darcy, have tried both of those;

Opening t/b a bit & does fix it as for some reason it doesn't seem to go below 75 iac steps when at idle, but when cruising it does, but yeah adjusted t/b blade until right on the 75 step mark so it still has full control(when hot op temp) & does help it but thought there must be a correct like throttle follower or something to adjust(but I don't have much experience with this so didn't want to fudge too much!)

With the desired air rate in each gear & P/n I did up the 1st gear a smidge as around the area it falls the data tracing say's it at was factory calibrate at -10, but I didn't touch the p/n side of assuming because it's in gear should be the 1st gear table. But yeah didn't seem to make much difference!


Thanks for the thoughts though!

[Jayme]

you could go right down to like 25 steps at idle when hot and still retain full control. I usually leave them round 25-50 and they are good. with a cam id say it needs more air to idle and on decel its programmed to sit the iac on a certain number of steps. the throttle stop needs to be open enough for it to be able to keep running at whatever the IAC is programmed to sit on during decel.
either that or increase the programmed iac posisiton during decel.

[Holden202T]

open the butterfly more is my prefference!

[VX L67 Getrag]

I feel opening the butterfly is cheating! LOL

I like to be complicated, I have found the maximum throttle follower steps is set at 75, but not sure how that is going to help it has 75 for 00 to 3200 rpm table!

But there is also a throttle follower table that looks like it's a multiplier steps/tps% & has range of 00 rpm set at 2.52, 400rpm set at 1.28, 800 to 6400 rpm set at 2.00!

I'm thinking if I allow more of maximum steps & also bump up the multiplier table at the low range, but don't want to start making it go erratic?

Thanks again for replies!

EDIT; added the log of it stalling & use the ver 1.05 vx-vy v6 adx!

[Jayme]

how is it cheating? bigger cam needs more air to idle... open butterfly till the IAC is back to how many steps it sits on with a stock setup and you are perfect - no dodginess or cheating has happened yet you are just unnessesarily complicating things.

[delcowizzid]

75 steps hot idle is too high anyway open the TB screw LOL will have so much nicer idle control when the IAC doesnt have to move half an inch to change rpm LOL

[Holden202T]

i actually found that increasing the butterfly to just below idle rpm seems to work better for my new cam in the 202 (bigger than the previous one) i have about 5 iac steps at idle now and that seems to stop any hunting issues i was getting