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chasing odd trims


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hey guys! 
3576 turbo 
using a BF F6 tune including stock injector data (still stock injectors) 

chasing an odd issue. with at idle. the LTFT trims are stupid. 
in park > long term trims are +12ish, but at times they will be under 5% 
in drive they are between -2.5 uptoo +3.9
(has been smoke tested on the intake) 
an no exhaust leaks, that i can hear

idle spark in drive holds solid between 9.5 - 10.5 (it asks for 10)
(still need to see what it runs for at idle in park with no load)

it did have a 3582r on it before hand. the trims were perfect, ever since changing over. its been a pain in the bum 

Edited by dat111
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mr dyslexic here.
wouldn't it be asking for more fuel in drive hence decent trims apposed to the terrible trims in park/netural

could dashpot have anything to do with it? as from my understanding dashpot is part of the compression side of things 

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  • 2 weeks later...

Is the replacement 3576 turbo a Genuine Garrett or is it a Genuine Imitation China Turbo..?

The reason I ask is that I have been road tuning, for a friend, a Dedicated LPG AU2 fitted with an imitation China Ebay 3582 mounted on a BA XR6T Manifold. Yes it is an AU SOHC Intech 6. 

It really had us chasing our tails with how inconsistent the car would behave and how it would respond to changes in the timing and how that would also affect the mixtures.

It turned out that the wastegate flap was too large for the recessed seat the manufacturer had machined into the Turbine housing, and as a result the flapper sometimes catching on the inside of the wastegate port and not sealing, or sometimes the flap would catch on the lip and then it would not seal shut again, and then even more messed up, the manufacturer had welded the wastegate Arm onto the shaft in such a position that when the wastegate actually sealed against it's seat, then it would finally make boost and the actuator rod would pass so close to the centreline of the pivot point, the shaft, that the actuator had almost gone over centre, and the actuator spring was unable to pull the wastegate closed, unless the car somehow hit a large enough bump on the road, then the wastegate would suddenly snap closed again.

Because the wastegate was behaving so erratically, the exhaust back pressure would change depending on how far open the wastegate had gotten stuck, which then changed Idle fuel mixtures, part throttle mixtures, cruising mixtures as well as how much timing the engine would take even without boost.

After dismantling the wastegate, and re-machining the Wastegate seat larger, shimming the flapper on the arm to stop it flopping over far enough to catch on the inside edge of the wastegate port, and welding the wastegate actuator arm on in the same orientation as the Factory Garrett GT3582R, so the arm moves from 2 O clock position when closed to 4 O clock position with the wastegate wide open, with the 12 O clock position pointing towards the wastegate actuator.

Only then was I finally able to stabilize the Fuel mixtures, and from there adjust the timing.

Even a blocked Catalytic Convertor or Collapsed internals in a muffler could be causing you grief...

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