How to properly increase idle from 650 to 700-800
04-07-15, 08:14 AM
#1
How to properly increase idle from 650 to 700-800
Hey guys, looking for some insight on a topic that is discussed often but I wanted to start a thread that would apply to my setup.
I have a JDM 6speed supra map based ecu on my sc300 and it currently runs excellent, no idle issues, stalling, problems etc etc. The intake manifold / throttle body setup is completely stock. The EGR has been deleted.
I have never touched any idle screws on my throttle body, as far as I know it's at the factory settings. The only thing I've adjusted is the TPS position to achieve the timing lock and adjust timing properly.
Currently the car starts and cold idles at roughly 1250-1300 rpm and slowly drops to a operating temp idle of 600-650 rpm , A/F is stoich at 14.7-15.1 ish. I'm pleased with how well the car runs but what I would like to achieve is a slightly higher idle, say 700-800ish rpm at operating temp. I understand that in theory the ecu will adjust idle back down via IACV but I've read that slight adjustments can be made still.
My question to the clublexus 2JZGE guru's is how do I slightly bump up this idle without going completely in the wrong direction? I've never touched the idle screws purely because of all the issues I've read on here.
Should I adjust the throttle set stop screw slightly clockwise in to achieve a higher idle and then lock it back into place? Or should I slightly adjust the throttle bracket screw and back it out slightly?
Picture of said car to appease the thread
:
I have a JDM 6speed supra map based ecu on my sc300 and it currently runs excellent, no idle issues, stalling, problems etc etc. The intake manifold / throttle body setup is completely stock. The EGR has been deleted.
I have never touched any idle screws on my throttle body, as far as I know it's at the factory settings. The only thing I've adjusted is the TPS position to achieve the timing lock and adjust timing properly.
Currently the car starts and cold idles at roughly 1250-1300 rpm and slowly drops to a operating temp idle of 600-650 rpm , A/F is stoich at 14.7-15.1 ish. I'm pleased with how well the car runs but what I would like to achieve is a slightly higher idle, say 700-800ish rpm at operating temp. I understand that in theory the ecu will adjust idle back down via IACV but I've read that slight adjustments can be made still.
My question to the clublexus 2JZGE guru's is how do I slightly bump up this idle without going completely in the wrong direction? I've never touched the idle screws purely because of all the issues I've read on here.
Should I adjust the throttle set stop screw slightly clockwise in to achieve a higher idle and then lock it back into place? Or should I slightly adjust the throttle bracket screw and back it out slightly?
Picture of said car to appease the thread
:
04-07-15, 10:40 AM
#2
the one circled in yellow is what you are supposed to use to bump up the idle.
you loosen the nut around it, and that will allow you to turn in the screw some.
you will want to make sure the throttle cable has a little slack in it or it will not allow the bracket arm to move freely.
the idle screw on top in yellow screw starts out not touching anything which is the default not raising the idle position, and as you screw it in maybe 1-2 turns you will feel it press up against something and get a little firmer, and from this point any more turns you do while its firm will open the throttle plate up some (cause screw is pushing thing that opens the throttle plate). Its pretty sensetive so once you get to that point, go like a turn or half turn at a time and see how it is acting. I usually do it after a gte ecu swap cause the little extra air helps to keep the idle from dipping a little bit when it likes to idle at 650 it can be a little annoying at times.
do note that this cracks open the thrrotle plate some, and the tps is on the throttle plate so the tps % will actually go up the more and more you open the throttle up.
why this is important is if you make more than a hair of a change (or even that) you probably want to turn the tps back a similar amount, this will keep you from having to reset the tps from scratch if your change throws it off enough. it really depends on where they set it originally, if someone set it with some room to spare then you might be ok but if its set on the edge it will act funny at times if you do not readjust after raising idle.
you loosen the nut around it, and that will allow you to turn in the screw some.
you will want to make sure the throttle cable has a little slack in it or it will not allow the bracket arm to move freely.
the idle screw on top in yellow screw starts out not touching anything which is the default not raising the idle position, and as you screw it in maybe 1-2 turns you will feel it press up against something and get a little firmer, and from this point any more turns you do while its firm will open the throttle plate up some (cause screw is pushing thing that opens the throttle plate). Its pretty sensetive so once you get to that point, go like a turn or half turn at a time and see how it is acting. I usually do it after a gte ecu swap cause the little extra air helps to keep the idle from dipping a little bit when it likes to idle at 650 it can be a little annoying at times.
do note that this cracks open the thrrotle plate some, and the tps is on the throttle plate so the tps % will actually go up the more and more you open the throttle up.
why this is important is if you make more than a hair of a change (or even that) you probably want to turn the tps back a similar amount, this will keep you from having to reset the tps from scratch if your change throws it off enough. it really depends on where they set it originally, if someone set it with some room to spare then you might be ok but if its set on the edge it will act funny at times if you do not readjust after raising idle.
Last edited by Ali SC3; 04-07-15 at 10:45 AM.
04-07-15, 11:47 AM
#3
Went out and adjusted the stop screw in slightly. Just like you said once it firms up the idle audibly changed upwards and I locked it down at 800-850rpm. I could tell the TPS was off because the tune went wonky and the fuel compensation went away (Car started idling super rich like 11.5:1). Adjusted the TPS counter clockwise all the way and came back clockwise slightly and you could hear the ECU re-enter closed loop and started adjusting fuel back to stoich A/F 14.7:1.
The idle bounced around from 800-850 for a bit then came down to 700-720, and now it's around 650-700 rpm. I'm assuming this is the ecu relearning the IACV position so I'm back to square one.
The idle bounced around from 800-850 for a bit then came down to 700-720, and now it's around 650-700 rpm. I'm assuming this is the ecu relearning the IACV position so I'm back to square one.
Last edited by HiPSI; 04-14-15 at 07:32 PM.
04-14-15, 07:34 PM
#4
Update.
Fiddled with the idle screw again today. Slowly adjusted the screw more in slightly and the ECU stopped being able to drop the idle any further. There seems to be a magical spot that the ecu likes which is right at 800 rpm. I accidentally turned the screw in to much achieving 1000rpm idle and the TPS could not physically turn any further counter clock wise to compensate for it. Brought it back to around 800rpm and the TPS was back in range and ecu was happy.
Fiddled with the idle screw again today. Slowly adjusted the screw more in slightly and the ECU stopped being able to drop the idle any further. There seems to be a magical spot that the ecu likes which is right at 800 rpm. I accidentally turned the screw in to much achieving 1000rpm idle and the TPS could not physically turn any further counter clock wise to compensate for it. Brought it back to around 800rpm and the TPS was back in range and ecu was happy.
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rcunamay (12-15-19)
04-17-15, 12:40 PM
#7
yeah I noticed that after raising it to 800, when I hot start it it will be around 650-700 and a little lean but then after a minute its back up to 800. Pretty normal and much better than it wanting to idle at 450 on a hot start and waiting for the IACV to adjust. these motors with a turbo attached warm up pretty fast compared to stock.
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