That's why I like to unplug the IAC and use the screw to set the idle, stays more constant that way too. Once I get rid of the gm ignition it should run pretty good.
That's why I like to unplug the IAC and use the screw to set the idle, stays more constant that way too. Once I get rid of the gm ignition it should run pretty good.
Originally Posted by eight
no, you just like to unplug yours because it doesnt work correctly
yea or somethin like that
I did the same thing on my VW when I installed a big cam. The ISV couldn't compensate, so I just upped the idle a little. Sucked for cold start though, only ideled when warm.
Last edited by Jackasic; 04-21-2006 at 08:04 AM.
1000cfm is really not all that much for a multiport setup, there are plenty of 350hp street cars runing 1000cfm tb's. I dont thing the cfm really has all that much to do with idle quality on efi, and it seems to me efi really can use that much cfm and not give up much low-end. i have a friend with bds birdcatcher (3500cfm?) on an 8-71, and after craig railsback helped with the tunin' it idled amazingly better than it did with only 1500cfm of carb. truthfully how many race efi(low impedence) set-up's have u ever been around, the issue is 60lb+ injectors fawkin the idle not the cfm. I think my idea of a race motor and yours are 2 different things.
thats true. i have no experience with big race motors. displacement and idle speed are related. the experience i speak from is two totally custom systems, one using motec and the other using a custom controller built by A&M students. they were both on a 600cc yamaha, but either one was no less trick than any system out there. one had iac and the other didnt. one used hall effect sensors the other used mag sensors. the one without iac performed better. we were using high impedence injectors, but relatively speaking, four 28.6 lb/hr injectors on a engine that size is equivalent to low impedence on a big motor. getting a good idle that wasnt through the roof was an issue.
im not saying it shouldnt have iac. if i paid for that thing id expect it to have iac. when deleting iac cuts the weight of your throttle body to about 40% and you can make it idle, its a more than fair tradeoff. that weight on a 500lb car is much more important than it is on a 3500lb car.
i can guarantee you a 350 hp motor isnt pulling 1000 cfm through a throttle body, but with mpi you can tune to make it run fine. can you even get a dry tb with less capacity?
how do you figure that it was equivalent to low impedance injector on a bigger displacement engine?
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big injectors relative to the engine's requirement at idle
low z injectors open and close faster, I think you have your terminology backwards.
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true, i didnt think about that, i was thinking soley in terms of flow capacity, not triggering time. guess you could say im thinking about big (55 lb/hr) high z injectors, which is similar to the situation we were in. there was no option for low impedence injectors in the size we were using. maybe that would have solved some of our idle issues. the stock ls1 injectors were really too big for what we were doing. iirc the way we got around it was to actually measure the output of the injectors and compensate in the tuning. ive never messed with a system needing that big of injectors. is that the only reason anything above 55-60 lb/hr has to be low z, idle quality?
funny how a thread about IH turned into custom efi talk.
thanks a lot brandon. you're so stupid.
i do what I can
psst, jimmy...
jimmy does love him some red x's
I had to quote him and then copy and paste the link, now they work just fine
My bitch better have my money...
Through rain, sleet, or snow...
My whore better have my money...
Not half, not some, but all my cash...
'Cause if she don't,
I'm gonna put my foot in her ass.
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