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627,2rwhp on pumpgas
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255 Posts
Discussion Starter #1
Hi guys, my supra has become alitle bit strange.

First the idle sometimes "jumps" between 400 and 800 rpm at idle, just upp and down for a few sec then i stabelises (spelling?) this happens like 3-4 times under a 20 min period.

Second, the boost. Last week when I drove the supra home from my dad it didn´t boost over 1,1 bar (16 psi). And I went for a drive today and the same problem appaird (spelling?) again. If I turn my boostcontroler of it runs good (0,9-1 bar=13-14,5 psi)and if i set it at low boost mode it boosted 1,1 bar= 16psi (should boost 1,2bar=17,5 psi and if I set it to high boost mode the boost will only go up to 1,1 bar=16psi (should be 18-19 psi)?

I would be realy greatfull if you could help me with this, it´s realy irritating.
 

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1,784 Posts
i get that jumpy idle problem sometimes also...well lately i have noticed it and i am wondering what this is as well...i am pretty sure one of my o2 sensors is bad..but it seems that you might have a boost leak somewhere...it seems when i tried to get anwers for my unstable idle people would always say i had a small boost leak somewhere...i cant find it..but im goin with fmic and hardpipes soon so its not priority for me right now


Ant
 

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749 Posts
Idle up/down is caused by the A/C cutting in and out. The ignition control module speeds up idle anytime the A/C compressor electric clutch cuts in. This is done to prevent the compressor from loading down the engine and ensure adequate RPM provided to the A/C to provide effective cooling. Without knowing your boost controller type and the absolute settings I have no idea why boost will not go over 1.1 BAR. Stock turbos should be able to produce 1.2 BAR easily. They start getting inefficient above 1.2 though.
 

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Boost4fun
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1,848 Posts
Agreed.. Give us some more details on your mods ;)
With the idel: Just check it easily by switching off the A/C and see if the idle #´s are steady then. If yes it is the A/C comming on and off. If not maybe the iac motor?!
Gerd
 

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627,2rwhp on pumpgas
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255 Posts
Discussion Starter #5
The idle was not the A/C, a hose from the BC was loose. When it was hooked up everthing worked just fine :). Thanks for you answers
 
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