383 idle issues.help appriciated
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recently got a 383 lt1 camaro forged bottom end small cam (untouched heads and intake mani bolt onts) as some of u may have read,ivd been have the idle problem since i got it.on a cold start it fires up real goo and rpms stay at 600-700 at idle.at a stop thee same..after time of using it it starts idling at 1100 1000 at a stop..but thing i put it in park and it comes up to 1500 rmps and stays there till i shut her dwn..i replaced 1 o2 sensor due to the fact the idk how but i was draging it on my way to work.spoke to the previos owner said they were installd no to long ago so im assuming the other one is still good...thanks alot for ur help
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could be anything...
vacuum leak
bad tps (or needing adjustment)
bad IAC
throttle body needs adjustment (do you have holes drilled? Do you have the IAC hole drilled through)
When going 383 the idle is a big thing to get down that plagues a lot of people. You need to slot your TPS and read the volts and make the proper adjustment as well as drilling through the IAC hole starting with stock diameter and moving larger if you need it. Better idle quality than drilling the blades or tipping them.
vacuum leak
bad tps (or needing adjustment)
bad IAC
throttle body needs adjustment (do you have holes drilled? Do you have the IAC hole drilled through)
When going 383 the idle is a big thing to get down that plagues a lot of people. You need to slot your TPS and read the volts and make the proper adjustment as well as drilling through the IAC hole starting with stock diameter and moving larger if you need it. Better idle quality than drilling the blades or tipping them.
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do you have an aftermarket tb, and if so, is the IAC hole drilled through? The first thing to check for is that... to get a nice smooth idle you'll need the IAC drilled through to the stock dimension. If that's sufficient great, if not, take it one size up at a time and check it out. You'll also need to make sure your TPS is reading the proper voltage, and if needed drill/grind slots into it where the bolts go to allow for further <----> adjustment if needed. You go by the voltage reading. Vacuum leaks are a common culprit, and a dead IAC won't be able to compensate and adjust the idle and can also be an issue.
I chased down this **** on my 383 build for a long time and eventually found a combination of the IAC passage issue, a bad IAC, and a TPS out of spec.
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Not to derail your thread, but just curious why you (and many others) choose an aftermarket TB over a ported 52mm stock TB
The reason I ask is they cost 2-3 times as much as a stock ported one and cause far more issues than a ported factory piece. From what I've gathered; 58mm is more than needed for 99% of LT1 builds....just saying....all these aftermarket TB's seem like a scam to make money for the aftermarket companies for very little HP gain and cause problems like you mention. Discuss!
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Once you put a airfoil in it there should be no difference in flow vs. an aftermarket 52mm TB...for less than half the price and no idle issues.
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A 52mm tb is great for a stock/bolt on LT1, or anything small-mild build wise. But for the 383 guys like me and him, a 58mm tb is well worth it. I would never pay what they cost brand new, I agree with you there. I got my Holley 58 brand new for 200 bucks... Bought it not only for the upgrade but to match the rest of my engine. When you've got a few grand in powdercoat / polishing a few hundred on a throttle body already polished that's great quality and will net some good HP gains is well worth it.
Since you've got a Holley like me start off with the IAC passage. Take the TB off the car and look inside straight on, the same way it would be mounted on the car. At the bottom of the )( there will be a hole that directs air into the IAC that mounts on the bottom.
Take a drill bit and check the hole on the stock TB, and use the same size to drill through the Holley. Compare the two TB's, stock and holley, and you will see exactly what needs to be done. Drill straight through and be precise.
This is a necessary thing with a 383 build especially and should solve your issue. If not, it's gonna be the other things I mentioned. Like I said if you need more help PM me and I can walk you through it!
Since you've got a Holley like me start off with the IAC passage. Take the TB off the car and look inside straight on, the same way it would be mounted on the car. At the bottom of the )( there will be a hole that directs air into the IAC that mounts on the bottom.
Take a drill bit and check the hole on the stock TB, and use the same size to drill through the Holley. Compare the two TB's, stock and holley, and you will see exactly what needs to be done. Drill straight through and be precise.
This is a necessary thing with a 383 build especially and should solve your issue. If not, it's gonna be the other things I mentioned. Like I said if you need more help PM me and I can walk you through it!
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A 52mm tb is great for a stock/bolt on LT1, or anything small-mild build wise. But for the 383 guys like me and him, a 58mm tb is well worth it. I would never pay what they cost brand new, I agree with you there. I got my Holley 58 brand new for 200 bucks... Bought it not only for the upgrade but to match the rest of my engine. When you've got a few grand in powdercoat / polishing a few hundred on a throttle body already polished that's great quality and will net some good HP gains is well worth it.
Since you've got a Holley like me start off with the IAC passage. Take the TB off the car and look inside straight on, the same way it would be mounted on the car. At the bottom of the )( there will be a hole that directs air into the IAC that mounts on the bottom.
Take a drill bit and check the hole on the stock TB, and use the same size to drill through the Holley. Compare the two TB's, stock and holley, and you will see exactly what needs to be done. Drill straight through and be precise.
This is a necessary thing with a 383 build especially and should solve your issue. If not, it's gonna be the other things I mentioned. Like I said if you need more help PM me and I can walk you through it!
Since you've got a Holley like me start off with the IAC passage. Take the TB off the car and look inside straight on, the same way it would be mounted on the car. At the bottom of the )( there will be a hole that directs air into the IAC that mounts on the bottom.
Take a drill bit and check the hole on the stock TB, and use the same size to drill through the Holley. Compare the two TB's, stock and holley, and you will see exactly what needs to be done. Drill straight through and be precise.
This is a necessary thing with a 383 build especially and should solve your issue. If not, it's gonna be the other things I mentioned. Like I said if you need more help PM me and I can walk you through it!
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I want to see some evidence of gains going to 58mm TB; who's got a dyno (or timeslip) comparison of a 52mm vs 58mm TB on a built stroker? Inquiring minds want to know how much this 52mm TB is supposedly holding back my mild 383
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