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NEED HELP!!!! Anyone running the Holley 58mm throttle body on there lt1?
If so has anyone had the problem where the car would idle fine at start up but once u get on the gas to rev it up it will stay at 1500-2000rpm and not go down unless u hit the gas pedal hard and fast then will go back down to about 1000rpm or so, also when i take it out of gear when driving it will still hang around the 1500-2000rpm range and stay there, or if I’m going 35 mph or so it’ll keep going tht speed without me hitting the gas pedal, the car runs good other than tht I’ve replaced the throttle position sensor and the iac sensor and still does this idk Wht else it could b, any help would b great, thanks
Scanner? Did you set minimum air rate? What is TPS setting. The larger 58 throttle body allows more air at idle at the TPS value the stock 48. I would set min air rate to 450 RPM. Reset TPS to .50 volts which may require modification to make TPS adjustable. See how it does? It's possible tuning could be required to correct what is called " decel sail on" condition which is a modification of how IAC reacts on deceleration.
Minimum Air Rate AKA as base idle is set by grounding ALDL to flash codes. When ALDL is grounded the ECM commands components it controls to activate. The IAC will fully extend, unplug it. Turn off key remove ALDL ground then start engine. Adjust throttle plate screw so idle is at 450 +/-50 for stock engine. Modified engine may require a little more but essentially slowest stable idle. Then turn key OFF before reconnecting IAC. Reconnecting IAC with key on can "spike" ecm. If you have a scanner check IAC counts 20-30 is normal, and TPS. You may have to make TPS adjustable, if it's out of spec.
How would u ground it, I’ve never done nothing like this before
and the throttle screw is set all the way back so I can get it to idle the lowest I can and thts at about 1000-1200rpm at start up
Does that TB have a hole in the bottom center for the IAC? My LPE/Accell did not. For years I couldn't figure out why the car would be fine at start up, but would either idle really low and/or die at a stop light. It would take a certain amount of start cycles, usually about 1/2 tank of gas before the PCM would compensate. I finally realized the TB had no hole to draw air from the plenum. Once I did that it was fine. I don't know what it is called, but do a search on here for the correct sized hole. Don't drill larger than stock. Even when my 396 had a solid lifter cam it would idle just fine.
If you have adjusted the throttle stop, take the TB off and only adjust it to where you just start seeing daylight out of the blades. That's all they are supposed to be adjusted to anyway. If you haven't checked the voltage for the throttle position sensor that is a must as well.
No I haven’t done nothing to the intake, I moved the blades and it don’t feel like it’s sticking at all it moves smoothly like it should, and yes there’s a hole for the iac and there’s nothing disconnected or broken to cause a vacuum leak I’ve checked everything and I can’t seem to figure out y it’s doing this
I told you wrong the scientificalness of drilling a hole in the TB. It is called the "drill mod." Some aftermarket TB's do not have a passage drilled through the TB. This passage is there for the IAC to draw filtered air, regulate it via IAC and then feed metered air into the plenum.
Here is where the hole should be:
If I were you I'd take the TB off to see if a there is a passage in this location. I have read the passage is either 1/8" or 5/32's. I thought I read it was also 11/64's which is what I drilled mine out to and it works fine. I'd suggest you do 1/8" first and see how it reacts. If there's already a passage, don't mess with it and pay more attention to your TPS. You need to elongate the mount holes in order to be able to adjust it. With the blades closed it should be in the .7v range with blades closed and 5v WOT.
All this info can be found here or cz28.com.
Yes I have those passage holes on the throttle body, it looks exactly like tht
for the tps sensor, I’ve replaced this like 100 times, it works for a second then it acts up again so I figured it wasn’t the tps and was something else but idk Wht it is
Yes I have those passage holes on the throttle body, it looks exactly like tht
But is there a passage that goes all the way through? If it's not a direct passage, shine a light through it through one end and see if you can see it on the other side?
for the tps sensor, I’ve replaced this like 100 times, it works for a second then it acts up again so I figured it wasn’t the tps and was something else but idk Wht it is
When you go to a different TB the voltage must be checked. The blades may not be in the same position which can then influence the actuator on the sensor to supply false readings to the PCM.
I told you wrong the scientificalness of drilling a hole in the TB. It is called the "drill mod." Some aftermarket TB's do not have a passage drilled through the TB. This passage is there for the IAC to draw filtered air, regulate it via IAC and then feed metered air into the plenum.
^^^
K... pretty sure this is some bullshit. I believe the hole to be drilled is actually a bleed hole and not a direct passage into the IAC. Been too long since I did this I've pretty much forgotten how a frickin' TB works. Dang it!
I was thinking this was obd1. 97 is.OBD2 2 you will need a scanner, to straighten it out. It still may require some tweaking on IAC function.within the tuning.
Don’t the tps only go on 1 way tho, I mean ik there’s a sertin way tht it sits down in there but
It does, but that's why I said the holes need to be elongated so you can adjust it. Writeups everywhere on this site about it. You do not need a scanner. You need a volt meter and a Haynes manual for which wires to prod when adjusting.
You can always buy an adjustable TPS:
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Idle problems 
