58mm TB swap progress
Thread Starter
Joined: Feb 2008
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From: Bolton Masshole
58mm TB swap progress Today i pulled my intake, TB and everything else. Ported my intake (Not perfect but it will do haha), cleaned it, and painted it black (it was red before). The paint is drying right now at work, and when i get back in the morning i will finish up. My question is, i swaped over my IAC and TPS, but do i need to do anything to them for the car to run right, or should i adjust by itself. It is a 58mm Prof. products TB if that matters at all. Also, where the TPS is, there was a "gasket" that appeared to be made of orange RTV. Is this stock, and can i swap it right over to the new TB? Thanks guys
Today i pulled my intake, TB and everything else. Ported my intake (Not perfect but it will do haha), cleaned it, and painted it black (it was red before). The paint is drying right now at work, and when i get back in the morning i will finish up. My question is, i swaped over my IAC and TPS, but do i need to do anything to them for the car to run right, or should i adjust by itself. It is a 58mm Prof. products TB if that matters at all. Also, where the TPS is, there was a "gasket" that appeared to be made of orange RTV. Is this stock, and can i swap it right over to the new TB? Thanks guys
You'll want to verify that your TPS sensor is reading the right voltage when you manually have your blades closed all the way and opened to WOT.
You also want to verify that you get the same readying with the pedal at nothing and pedal at WOT.
You will need a scanner to really dial it in correctly to make sure the IAC counts are correct, but you can get close with just a DMM. You will have to slot the holes in the TPS sensor to allow manual adjustment. With the car on accessories set the TPS so that 0% throttle corresponds to ~.65v TPS voltage. For 93's use .5v. If the car will not idle, open the blades a tiny bit and reset the 0% throttle to .65v and try again. With a scanner it is easier since you can just adjust the blades until IACs read in the proper range and then set the TPS to .65 at that point.
I used to have a PP 58mm and with bolt ons it worked great, but after a H/C swap it needed the "IAC Mod" to idle properly. That does not say anything bad about PP though, since my AS&M that was twice as much needed the same thing done!
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IAC MOD? hows that done.
"Also, you may need to set the resting position of the throttle blades slightly more open with a cam to get enough airflow at idle – that can cause the idle to bounce. I’d recommend opening the blades maybe a half turn and see if that helps."
How do I do this?
"Also, you may need to set the resting position of the throttle blades slightly more open with a cam to get enough airflow at idle – that can cause the idle to bounce. I’d recommend opening the blades maybe a half turn and see if that helps."
How do I do this?
The TPS is a variable resistor, and the voltage changes depending on how much it is turned. Slotting it lets you turn it some manually to set the resting voltage. Heres the link from Golen in setting the TPS - a picture is worth a thousand words! http://www.golenengineservice.com/html/tps.html
The IAC mod is to isolate the IAC passages from the regular intake plenum to help the idle on a big cam. That tiny hole under the TB opening leads to the individual runners so the car can get an even supply of air to each one. With a big cam, if you rely on just the TB blades then only the front runners get enough air to idle proplerly - basically the difference between a shot of nitrous in the intake elbow where the front cylinders get more nitrous and a direct port system where each runner gets the same exact amount. On aftermarket TBs the IAC passages are routed right behind the blades and into the intake instead of through a hole and seperated into the dedicated IAC passages. The mod drills a hole through the throttle body right in front of the IAC passage and then isolates the IAC air into the correct passages. Again though, it is easier to show then explain. http://members.***.net/chipsbyal/page/idle/tbi.htm
Very easy and a lot simpler then it sounds
.
The IAC mod is to isolate the IAC passages from the regular intake plenum to help the idle on a big cam. That tiny hole under the TB opening leads to the individual runners so the car can get an even supply of air to each one. With a big cam, if you rely on just the TB blades then only the front runners get enough air to idle proplerly - basically the difference between a shot of nitrous in the intake elbow where the front cylinders get more nitrous and a direct port system where each runner gets the same exact amount. On aftermarket TBs the IAC passages are routed right behind the blades and into the intake instead of through a hole and seperated into the dedicated IAC passages. The mod drills a hole through the throttle body right in front of the IAC passage and then isolates the IAC air into the correct passages. Again though, it is easier to show then explain. http://members.***.net/chipsbyal/page/idle/tbi.htm
Very easy and a lot simpler then it sounds
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I just drilled the hole and did not bother with any isolation on a BBK 58mm. Really helped idle quality. Much more steady than the 250 rpm swings I had previously with the IAC motor trying to maintain the commanded idle rpm.
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Verdad Gallardo Thread Starter
Joined: Feb 2008
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From: Bolton Masshole
right now the car runs fine, and will idle good at first, but after i start driving it, it will idle down top about 400 or so and really start to struggle. I wonder if i need to do this IAC mod thing? Or maybe i just need to adjust my idle screw
TECH Veteran
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you can do the slot the TPS crack the idle screw (really is a stop screw) to "trick" the TB and PCM into running right.
IMHO do the drill mod and DON'T F with the stop screw. You will need a scan tool to read IAC counts to do this, TPS can be read with a volt ohm meter.
In the end you wind up drilling a hole in the same place as on stock TB 1/8" at first then read IAC counts. This assumes your TPS is set to .67 vdc with blades closed and 4.5 vdc with blades open. IAC counts want to be 32 (30-35) with engine at operating temp.
Drill larger hole 1/64" at a time and check IAC counts again. Take baby steps you don't want to drill to big. On just a stock motoe you may get away with no hole but you are experienceing COMMON issues with any aftermarket TB. If you don't have the supporting mods put the stocker back on. If you do want the 58 then you will have to do what it takes to make it right. If you don't have a scan tool you are just guessing but 1/8" hole is a place to start.
IMHO do the drill mod and DON'T F with the stop screw. You will need a scan tool to read IAC counts to do this, TPS can be read with a volt ohm meter.
In the end you wind up drilling a hole in the same place as on stock TB 1/8" at first then read IAC counts. This assumes your TPS is set to .67 vdc with blades closed and 4.5 vdc with blades open. IAC counts want to be 32 (30-35) with engine at operating temp.
Drill larger hole 1/64" at a time and check IAC counts again. Take baby steps you don't want to drill to big. On just a stock motoe you may get away with no hole but you are experienceing COMMON issues with any aftermarket TB. If you don't have the supporting mods put the stocker back on. If you do want the 58 then you will have to do what it takes to make it right. If you don't have a scan tool you are just guessing but 1/8" hole is a place to start.
Thread Starter
Joined: Feb 2008
Posts: 1,265
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From: Bolton Masshole
i have a scan tool as well as a H/C 383, so i def dont want to put the stocker back on. I don't want to trick the TB either becuase it only doesnt idle right sometimes. Like i will coast into a stop sign, car will start to idle like ****, i will give the throttle quick blip to 1500rpms, and it will settle down and idle smooth again at 900rpm or so. Where exactly do i drill the hole? Also i didnt know there was a hole drilled in the IAC in the stocker.
i have a scan tool as well as a H/C 383, so i def dont want to put the stocker back on. I don't want to trick the TB either becuase it only doesnt idle right sometimes. Like i will coast into a stop sign, car will start to idle like ****, i will give the throttle quick blip to 1500rpms, and it will settle down and idle smooth again at 900rpm or so. Where exactly do i drill the hole? Also i didnt know there was a hole drilled in the IAC in the stocker.
If you look at the stock TB you will see the hole right in the spot where an air foil goes. On the intake manifold their is a corresponding passageway right behind it.
