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2jzgte small Singleturbo Idle Air Problem


Planlos1988

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Hello,

 

i have a little Problem with my little Singleturbo Build.

 

First, its a JZA80 UK-Spec (EU/US-Spec) Twinturbo with MAF sensor ;)

 

Turbo is the biggest Borgwarner s200SXE, i know its small but for my project (arround 500/550HP and verry fast Spoolup) i think its ok :)

 

 

So i would to keep my OEM EU-Spec Ecu and Injectors. So my MAF Sensor would also be keeped. For this reason i pluged all the vacuum lines that was in the Twinturbo vacuum section also in the vacuum section betweed the new Singleturbo und MAF Sensor (Idle Air Valve, valve cover brather and charocal tank).

 

Its all finished and i think with this little Singleturbo and and HP limit it should run with the OEM Ecu without a Standalone oder Piggy.

And its Running nearly well, but know the Problem! :)

 

 

-When im in idle the engine runs well, then when i push the accelerator that the rev is 3500 or more and take back from the accelerator fast then the rev sinks realy down to arround 300/400 for a second or two and the afr runs realy to fat (sometimes the enginge also stops running) and after two or three seconds the rev and afr normalize..

 

 

When im going slow or not complete from the accelorator there is no problem.

 

Thats the only Problem i have.. And i dont know what im doing wrong..

how i said all vacuum lines that are original in the intake section of the original twins are back again in the intake section of my singleturbo also between turbo and maf..

 

Idle Air Valve is clean.

 

What do you think? Would be nice if anyone has a good idea what i can check :)

And i hope you can understand my bad english :)

Edited by Planlos1988 (see edit history)
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The fact that you have changed the turbo shouldn't really affect idle control, rechecking all pressure hose connections etc may reveal the problem,however i am not sure just how the UK spec ECU handles running both MAP and MAF when it comes to idle air,, i also suspect that you will see problems with trying to run this setup at the higher airflow's, that the turbo capable of supplying enough airflow for 550BHP. as this will likely trigger fuel cut, due to this, and max out the resolution of one or the other.

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First, thanks for the replys. That was also what i thought that the new Singleturbo shouldnt really affect the idle air control and if the oem ecu dosent fit that small turbo (i dont think that the airflow is not much more like the original twins in ttc mode) that it has a affect when driving in boostmode but that i will see later when the first driving is comming :)

 

I will chec all pressure hose conections but they are all new and i think that all pressure hoses are back again in pressure section after the turbo and all vacuum lines are back in vacuum section befor the turbo behind the MAF sensor. But how knows of i plug anything wrong. I check that :)

 

Where is the map sensor? I only know there is a turbo pressure sensor in the intake (there where is the map sensor on jspec) or is this the map sensor? Because i thought the ukspec only has a maf sensor

 

And yes Bov is to athomsphere. But that was also before the single turbo with the twins with no problems. But i also testd it when im put the vacuum line from the bov off so that it dosent open and the problem is the same with no change.

 

 

Edit:

I checked the hks bov and let it recirculate but that was not the reason.. same effekt.

Then i checked the vacuum lines and i think they are all right.

But, with oem twinturbos the vacuum lines and the idle air valve line are "far" away from the MAF and Airfilter. But, because of that the Singleturbo needs not that long ways from the air filter there are only arround 15/20cm between MAF and Turbocharger and between that (arround 5-10cm away from MAF) i plugged in the Idle Air Valve Line, the two valve cover brather and the vacuum line from the charocal tank. They all have there own connection but not far away from the MAF, how i said arround 5-10cm.

Could that be the Problem that its to near so that the MAF cant read the right airflow in idle, when i push the accelloraror and push it of fast?

 

Or could the idle air valve needs to long to open enough to give enough air so that it could be a little malfunctions?

Edited by Planlos1988 (see edit history)
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Yes im sure.

 

And with the oem twins the HKS Bov was also installed and dosent recirculate without problems.

 

Edit:

I read in antoher Supra Froum that the IAC Valve line should not longer then 4feet. Im not at home but will see on monday if mine is longer because i think it is. Could that be the problem?

Edited by Planlos1988 (see edit history)
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Little Update, i looket today morning how long my idle air valve line is. And its arround 2meters. I will shorten it in the evening when im back from work and test it if thats the problem. Would be nice if that little thing fix the problem :) i will hope and short it to max 120cm and test again.

 

Edit:

Now its only a bit more then 1 meter long.. but the problem still remains.. tomorrow i will do a testdrive. The Ecu had more then 4 month no power so who knows if its better when im driving a bit.

Edited by Planlos1988 (see edit history)
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News :)

 

im driving a bit today and it runs well but the idle/load cycle issue is still allive..

 

I checked the idle air valve but it opens and closes like discribed in the 2jz manual..

 

i also dont think its the air mass meter because in every other situation it runs verry well only load cycle to idle dosent work..

 

and i think the vacuum lines are also all right ive checked them many times :D

 

so what could it be..? ecu? or any other ideas what can i check?

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Its a small single, s200sxe its only to should reach 500/550hp like bpu with my old eu twins but without the issues the twin system could have :)

I know what you mean. But everything is perfect afr on boost or no boost, also in idle. Only the load cycle back to idle runs bad..

 

And i read from other in us forum they fittet also s300 with stock us ecu and maf and it runs good.. (i have uk spec but it should be the same with maf)

 

Could it also be a problem with the hks fcd? It was installed when i buyed the car and it runs good but i dont know if it could be a fake and read much abaout people having problems with fake fcd after batterie change or longer time with no power..

Edited by Planlos1988 (see edit history)
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In idle the afr is arround 15,6 and 14,4 just above ide (arround 1000rpm) its the same and when refs dropp its also the same.

 

But i think i know the problem..

My turbicharger has anti surge so that means that the air can pass backwards the turbocharger when the air pulls back. I have a blow off but i think that there otherwise comes air back and my maf is arround 10-15cm behind the turbocharger and the back going air issued the maf..

I test it when i put the maf arround 30cm away from turbocharger that make it much better, so then the problem is at arround 3500/4000rpm and above and not like before on 2000/3000rpm and above..

Ot runs also not that much rich when im leave the throttle bevor it was afr 10 and under (my gauge only shows 10-17) and now its 12, says much better.. but what can i do? There is not enough place to put the maf a half meter away from turbo xD

 

So im thinking to buy a HKS VPC to eliminate the MAF and going MAP with it.. but does anyone has one fore sale for the supra mk4? :D

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  • 2 weeks later...

News...

 

I have installed the Synapse DV and recirculate it but it dosent change the problem.. same at all..

 

The i installed the VPC with A-Chip and now the problem is gone but.. yes theres a but xS..

 

it runs well when the engine is cold but when its become hot it runs realy lean that my AEM AFR cant show it anymore.. i can also spin the idle knob to full but it dosent change :(..

also i can run it with a gcc and spin it to rich but it always runs to lean..

 

i checked all vacuum hoses bot i have no boost leaks everywhere..

 

i also have no error codes so its all installed right also the 1200ohm resistor...

 

what could that be?

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  • 4 weeks later...

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