Idle Issues: Who wanna help out?
Idle Issues: Who wanna help out? 24x converted car.
Started car with foot slightly on pedal reving it to 1300-1400 rpm for 15 minutes like my machinest requested. I take foot off pedal and it dies.
I initially took the PCM to one of my local tuners that have experience with LT1s and 24x conversions. Idle rpm was set to 800 rpm and idle air flow had been increased a decent amount (do not know what exact percentage). I have no O2 sensors and currently ordering my wideband.
I have capped off all vacuums for the time being except for PCV, and brake booster. I am borrowing scanner this evening to check IAC and TPS percentage. What else am I looking over? I think a retune or percentage change is necessary....
Edit: It is a Summit 58MM TB
Started car with foot slightly on pedal reving it to 1300-1400 rpm for 15 minutes like my machinest requested. I take foot off pedal and it dies.
I initially took the PCM to one of my local tuners that have experience with LT1s and 24x conversions. Idle rpm was set to 800 rpm and idle air flow had been increased a decent amount (do not know what exact percentage). I have no O2 sensors and currently ordering my wideband.
I have capped off all vacuums for the time being except for PCV, and brake booster. I am borrowing scanner this evening to check IAC and TPS percentage. What else am I looking over? I think a retune or percentage change is necessary....
Edit: It is a Summit 58MM TB
Last edited by SwampWS6; Aug 3, 2015 at 03:25 PM.
Make sure your tuner knows he is working with a LT1 TB and not a LS1.
Also, you will most likely need to fix the IAC passage in the TB since its a aftermarket piece. Gotta either drill the blades or crack em a little, probably maxing out IAC as is now.
Also, you will most likely need to fix the IAC passage in the TB since its a aftermarket piece. Gotta either drill the blades or crack em a little, probably maxing out IAC as is now.
On The Tree
Joined: Jun 2015
Posts: 182
Likes: 3
From: Portland OR
Does it still stall if you remove the IAC? Gasket or TB blocking passage?
If a stepper IAC is installed with the plunger extended it might jam or otherwise bork the IAC.
If the stepper wiring has been juggled the stepper may not move or move in reverse.
It is best to try to get it to idle on the stepper without opening the butterfly.
Generally the OEM setting for the throttle blade is open a half turn or whatever is needed to keep it from sticking closed. The reason for this is that PCV gack will accumulate and close any gap, eventually closing any adjusted gap.
With the stepper off the motor and plugged in, hold a finger on the tip of the pintle with light pressure (to keep it from getting spit out).
Have someone turn on the ignition, the pintle should extend fully and then retract to the programmed starting position.
The IAC has no position sensing, so the computer drives it all the way closed (extended) and them opens it to the programmed number of steps for starting.
The computer then keeps track of the steps so it knows the position of the IAC.
If a stepper IAC is installed with the plunger extended it might jam or otherwise bork the IAC.
If the stepper wiring has been juggled the stepper may not move or move in reverse.
It is best to try to get it to idle on the stepper without opening the butterfly.
Generally the OEM setting for the throttle blade is open a half turn or whatever is needed to keep it from sticking closed. The reason for this is that PCV gack will accumulate and close any gap, eventually closing any adjusted gap.
With the stepper off the motor and plugged in, hold a finger on the tip of the pintle with light pressure (to keep it from getting spit out).
Have someone turn on the ignition, the pintle should extend fully and then retract to the programmed starting position.
The IAC has no position sensing, so the computer drives it all the way closed (extended) and them opens it to the programmed number of steps for starting.
The computer then keeps track of the steps so it knows the position of the IAC.
Last edited by RixTrix; Aug 3, 2015 at 09:24 PM.
Thanks guys for the replys. I played with the throttle stop screw just a little and it idled between 739-800rpm via the scanner. Tuner tuned it for LT1 like he shouldve. Another question I wanna ask is, why so many LT1 guru's say not to adjust the throttle stop screw? In every search it says its controlled by the PCM, which I understand. I understand not adjusting on a stock setup but why have the feature if it is not meant to be tampered with? 9 out of 10 searches say dont touch it!
Are you gonna run a OLSD tune or use narrow band 02s?
People are overly concerned with split BLM issues from the wacky LT1 IAC passages in intake etc. Personally, slot TPS, crack blades to get IAC position in a happy place and leave it be. Thats how my is setup but I have no IAC passages like LT1 stuff.
Link to fixing TB IAC
https://ls1tech.com/forums/lt1-lt4-m...an-oem-tb.html
People are overly concerned with split BLM issues from the wacky LT1 IAC passages in intake etc. Personally, slot TPS, crack blades to get IAC position in a happy place and leave it be. Thats how my is setup but I have no IAC passages like LT1 stuff.
Link to fixing TB IAC
https://ls1tech.com/forums/lt1-lt4-m...an-oem-tb.html
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TECH Addict
Joined: Dec 2010
Posts: 2,610
Likes: 4
From: Maricopa, AZ
Idle Issues: Who wanna help out? Thanks guys for the replys. I played with the throttle stop screw just a little and it idled between 739-800rpm via the scanner. Tuner tuned it for LT1 like he shouldve. Another question I wanna ask is, why so many LT1 guru's say not to adjust the throttle stop screw? In every search it says its controlled by the PCM, which I understand. I understand not adjusting on a stock setup but why have the feature if it is not meant to be tampered with? 9 out of 10 searches say dont touch it!
To see if the AFR is split front to back, use an IR gun on each header primary and see if the temps are about the same. You can also trim this out in the tune, but should be fine with the TB blades closed and using the IAC if possible. However, some cams require more air flow than the IAC can deliver, so you'll have to drill the TB blades or crack them open a bit in order to idle.
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Verdad Gallardo Are you gonna run a OLSD tune or use narrow band 02s?
People are overly concerned with split BLM issues from the wacky LT1 IAC passages in intake etc. Personally, slot TPS, crack blades to get IAC position in a happy place and leave it be. Thats how my is setup but I have no IAC passages like LT1 stuff.
Link to fixing TB IAC
https://ls1tech.com/forums/lt1-lt4-m...an-oem-tb.html
People are overly concerned with split BLM issues from the wacky LT1 IAC passages in intake etc. Personally, slot TPS, crack blades to get IAC position in a happy place and leave it be. Thats how my is setup but I have no IAC passages like LT1 stuff.
Link to fixing TB IAC
https://ls1tech.com/forums/lt1-lt4-m...an-oem-tb.html
This is because the LT1 intake will feed the runners unequally if you don't use the IAC passages, which is what the IAC valve feeds, at no and low throttle inputs. If you crack your throttle body blades, it'll bypass the IAC valve and passages and give you a split BLM. But worse is that it'll split the AFR front to back (depending on the cam among other things) and can cause a lean condition on the front cylinders.
To see if the AFR is split front to back, use an IR gun on each header primary and see if the temps are about the same. You can also trim this out in the tune, but should be fine with the TB blades closed and using the IAC if possible. However, some cams require more air flow than the IAC can deliver, so you'll have to drill the TB blades or crack them open a bit in order to idle.
To see if the AFR is split front to back, use an IR gun on each header primary and see if the temps are about the same. You can also trim this out in the tune, but should be fine with the TB blades closed and using the IAC if possible. However, some cams require more air flow than the IAC can deliver, so you'll have to drill the TB blades or crack them open a bit in order to idle.
Im actually in a debate on whether to do SD or keep MAF. Im leaning towards SD. But trying to figure if I need O2s or not. Different tuners have different theories on whether O2s are needed. One tuner says you need them so it can let the PCM know if the car is running lean and some say ditch the O2, all you need is a wideband. Why people cant make up there minds
Everything my tuner has said indicates that the MAF options available that run on a 0411 PCM will be maxed out if you push them hard boost wise. So you end up paying for a MAF tune, then paying for a SD tune.
OL or CL is your personal choice, I run a OLSD because its simple and I watch my W/B very closely. During tuning and pulls on dyno, my tuner watches the narrow bands and W/B but doesn't let PCM make corrections based on narrow bands. OLSD requires more user input and watching of engine conditions.
Man I might have to send you a gift card or something. You put so much knowledge on me....... I dont have my own tuning software yet so I want to make make a viable decision. Is OL or CL safer?
I think I might try open loop since I already have O2s tuned out and purchased the AFR500 w/NTK calibration grade sensor
I think I might try open loop since I already have O2s tuned out and purchased the AFR500 w/NTK calibration grade sensor
OLSD is def more dangerous than CLSD, as OL will not react to bad gas, or faulty sensors. You can run super lean under boost and nothing will pull timing/dump fuel. So, pending how well you trust your tuner, fuel quality, and how aggressive you go with tune will dictate that. OLSD will also only be good for the strict combo it was setup for, so you can't slap in a different cam or turbo and hope it goes fine. Its fixed in its self but if its fixed well, you are good to go.
That being said, if you are WOT and something goes bad, CL doesn't use the 02s in WOT so you won't be saving much anyways.
Personally I would ask your tuner, mine was confident in an OLSD (granted a lot comes from OLSD being easier to tune AFAIK)
That being said, if you are WOT and something goes bad, CL doesn't use the 02s in WOT so you won't be saving much anyways.
Personally I would ask your tuner, mine was confident in an OLSD (granted a lot comes from OLSD being easier to tune AFAIK)
OLSD is def more dangerous than CLSD, as OL will not react to bad gas, or faulty sensors. You can run super lean under boost and nothing will pull timing/dump fuel. So, pending how well you trust your tuner, fuel quality, and how aggressive you go with tune will dictate that. OLSD will also only be good for the strict combo it was setup for, so you can't slap in a different cam or turbo and hope it goes fine. Its fixed in its self but if its fixed well, you are good to go.
That being said, if you are WOT and something goes bad, CL doesn't use the 02s in WOT so you won't be saving much anyways.
Personally I would ask your tuner, mine was confident in an OLSD (granted a lot comes from OLSD being easier to tune AFAIK)
That being said, if you are WOT and something goes bad, CL doesn't use the 02s in WOT so you won't be saving much anyways.
Personally I would ask your tuner, mine was confident in an OLSD (granted a lot comes from OLSD being easier to tune AFAIK)
I will discuss things with my tuner and see where he's at.
TECH Addict
Joined: Dec 2010
Posts: 2,610
Likes: 4
From: Maricopa, AZ
Idle Issues: Who wanna help out? That depends on the cam. I've seen it posted once or twice. Usually the ones that require a much higher idle. Displacement also plays a factor. It's not common at all. I still use my IAC for idle air.
Last edited by hrcslam; Aug 5, 2015 at 05:50 PM.
