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Autech Hc Values Too High On Idle..

Mathias1986
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Mathias1986 Explorer

Mathias1986

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Posted (edited)

Hi!

I have having lot of problems a couple of years now that my HC values are WAY too high on idle, but higher rpm everything is fine..

Have tried to check everything i can, nothing found.. Tried changing back to original dumpwalves but no difference..

Had it to nissan and checked with nissan consult, no problem there.. every sensor worked as it should and well everything was ok...

But it's going to rich i know because of alot of black spots on the rear and love to eat fuel...

I have a 3" exhaust system all the way and new 200cell cat and apexi airfilterkit and boost o 0,9bar.

But was the same before with everything original.. and the turbos and engine is in good shape..

No one has found out what it can be wrong yet with this rb26... im getting tired of this shit.... :(

Edited by Mathias1986
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https://www.sau.com.au/forums/topic/369002-autech-hc-values-too-high-on-idle/
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SMOKEYV35 Mentor

SMOKEYV35

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most likely a combination of a few things.

3" exhaust with a very free flowing cat converter (don't even think 200 cell is legal here in australia) - means the exhaust gasses are speeding out at a high rate, and not slowing enough for the C02 to burn off as they would in the stock system.

do you have anything higher than stock boost? as soon as the factory computer senses you're over stock boost, it retards the timing and richens the mixture significantly. if you are running with higher boost, next time you floor it, watch out the rear window - you will see the unburnt fuel just pouring out the back.

the wagon design, with the very upright rear tailgate creates a significant low pressure area behind the car. it basically sucks everything that passes over the car and under the car up onto the rear tail gate. it's why whenever you drive a stagea in the rain, within a minute the rear window is filthy. same goes for dust, road grime, and exhaust fumes!

Mathias1986 Explorer

Mathias1986

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Well i have tought about getting a Nistune for it so i have the ECU part fixed when the time comes for more power..

The boost may be a little over stock because of the highflow system on it.. but the HC values was the same with the stock exhaust system and cat too.. so don't really think it's that one.. and when the values are fine on higher rpm, only idle it's really bad..

wolverine Grand Master

wolverine

Posted
Posted

What are you using to measure HC?

The stock ecu will run pig rich with higher boost/more airflow. Sure in closed loop it will trim when cruising but there is no doubt that aftermarket engine management wakes these cars up and improves fuel economy compared to the factory ecu once you start modifying them.

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