hmmmm where did you put the whole, and how many??? Did u put one on each butterfly? or just one in left or right is fine.... Tell me where in this pic:

 

Nick... you've got to read carefully what people are saying, and UNDERSTAND it.. Three of us have told you the IAC controls the engine speed many different times BESIDES when the car is sitting still and idling. As the RPM increases, the IAC motor opens up so that the engine won't stall on the road if the throttle blades suddenly close. Then there are the "follower" tables mentioned above, which hold the engine idle speed (what the engine idles at then you take your foot off the clutch and are slowing down, etc.) elevated until the PCM sees a "0" VSS signal. That's what keeps the engine from stalling when you slow down. All of this is related to the IAC counts.

You want the IAC counts low enough to allow the headroom required by the PCM to do all the controls other than when the car is sitting still.

I have the Holley. My stock PCM controls the idle (a MoTeC ECU controls virtually everything else). I adjusted the blades EXACTLY the way I'm telling you. Adjust the blades until the IAC counts are below 40. Then check the TPS voltage and make sure it is below 0.90V. I didn't have to drill any holes, or do anything else to my TB to make the system work. I have slotted the TPS sensor, but that's related to how my MoTeC reads the signals (you baseline the TPS signal by entering the closed and open throttle TPS volts). My Holley actually had huge gaps between the blades and the bores, that caused a problem with too much flow, and I reworked the blades to get them to have a closer fit with the throttle body bores (aided by a nitrous "pop" that did evil things to the bladess ).

You have to get the TPS voltage down below 1.0V. If you keep it above 1.0V, you WILL GET A CODE, and the PCM can't set the baseline 0% throttle position, and you will not be running on the idle tables, you will be running on the engine load tables and the idle speed will be elevated. I mentioned 0.90V, because that gives you a cushion, but you can try it at up to 0.99V. I know for a fact when the TPS volts go over 1.00, you will have idle problems. Not sure why you are so concerned about slotting the TPS sesor holes... you can't even notice it.

 

K, at idle...what should the "sweet" spot be for my IAC position. Like I said its at 120ish now at idle now. I will adjust that set screw and try to get the TPS volt to not go over .90 and see how low i can get the iac.

 

There's no "perfect" spot. If you can get them to about 40 it should work.... but maybe 50 will work too. For a stocker, 30 is fine.... but you don't have a stocker.

 

Basically get them MUCH lower at around 120 the IAC is basically at the end of it's range and can't do much more but at around 30-40 the IAC can still open and close enough to get the job done and not let the car stall when it comes to rest.

As for the blades, take the TB off and put one very small hole in one of the blades. I would say start under a 1/8th (.125"), I'd go around .080" or so. Try that out and see what the IAC counts are like. You should see a decrease in the IAC counts with that and go up slowly till you find what gets you where you want to be.

I would first set the throttle blades at a position where they do not bind and are in the middle of the TPS voltage spectrum for idle.

Bret

 

IAC counts shouldn't be at 120 (normally). You need to adjust the idle screw and open the blades up (that big engine needs more air at idle than you IAC can feed it). I don't see why people drill holes in them when they come with an adjustment screw for that same purpose .


Start the engine and it will idle higher than 900 until the pcm adjust the IAC counts (lowers them) until it hits that 900rpm. I'd raise the idle to 1000, personally.

Ryan

 

This may be old news to you guys but ......Holley's do not have a proper throttle stop. When looking at the blades they will open all the way 90degrees to the bore, then keep going...they overcenter. I had to make a throttle stop.

 

ok well I adjusted the stop screw, it seems the lowest i can get it at idle was about 90-100 for the IAC position. I drove it around alittle, and it was still doing the same issue. Didn't die, just chuged like it was about to when I came to a stop. I pulled back in the driveway and the IAC position via datamaster was now between 70-85, i drove it around alittle more and still had the same issue. The stop screw is at its limit, anymore and it will start showing tps % @ .8 at idle and thats something we dont want. Looks like thats as low as its going. Injuneer you said you didn't have to drill anything, what would you recomend the next step being? Slotting the TPS sensor and getting it to that magic .65 volts? Its at .80 at idle now, so it is between the .65-.90 sweet spot for tps volt you were talking about. I REALLY dont want to drill the tb blades like your saying SStrokerace. Do you think there is another way? I guess we are getting somewhere though becuase the IAC counts have been lowered by 20+ish by adjusting that stop screw and the idle % is still reading 0.0 Post away.....

 

FWIW the 75mm LS1 TB blade has a hole in it from the factory.

Bret

 

This would be where i would start as well. I didnt check your log but if the IAC counts are maxed out when you are coming off the throttle then you can use the adjustment set screw thingy on the TB to keep the IAC down to a reasonable number when the throttle is closed.

Steve

 

Everyone has told you that you need to open up the blades until you get to 0.9V not 0.8 and/or you're IAC counts drop to 40 or so. If you can't get it done that way then you need to drill small holes in your TB. I think the "O" in Holley would be a good place to start. Drill one hole and see if it works, if not then drill the other "O". If that doesn't work, but you notice you IAC counts getting closer to the 40 range then you can go with a little bigger hole and be done. This is a common problem and can be fixed fairly easily, you just have to logically think it through. You have to find a way for the engine to get more air with the TPS sensor staying below 0.9V, so just adjust it to 0.9V and then go from there.

 

I got a .o625 hole in each blade and a .79 voltage. Works fine. Livin a charmed life here.

 

hmmm ok ill just drill the thing, ill let you guys know tomorrow...ill start drilling the 1 "O" in Holley with a 1/8" bit and see where i stand.....

 

Start out smaller than that. You can always go larger...

 

k the first hole I make, if it is not big enough would you make one the same size on the other blade OR would you make that first one hole bigger? Just curious