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Discussion Starter · #1 ·
Well I just got my car back from the tuner. She's not 100% but the guy just could not work out the rest of the bugs. So here I am....waiting for the ecu flash to fix all my woes. Until the flash for my year comes out I want to try to tackle this if I can.
Basic background:
I am boosting and loving it.
All custom setup...
Turbonetics t3/t4 .63ar blah blah
5-6lbs. on a .5bar tial wg (vacuum line to compressor housing), vent to atmo
greddy rs bov, recirc between VAF and compressor

While wot she boosts great, great afr 11-12, and hauls ass. I smoked a 350z without flinching today. (low rpm, all 4th gear, 65mph to 125mph) ...too easy.

Questions:
1. Is it normal for my aem uego wb to read 16+ or ... (all lean) when off the throttle after accel?
2. After about 20-30 mins of driving, boosting or not, little throttle, the car will lean out for several seconds and lose power then come back to normal for a few seconds then back and forth. (because of this I have to reset my ecu each time I drive) I assume this is the ltft kicking in?
3. I'm still adjusting my bov hard/soft. It seems as though no matter how soft I make it I still get that wonderful flutter sound...compressor surge? If yes, solution/ideas?
4. While normal driving (low throttle, under 3Krpms) the afr looks like a narrowband blinky light...especially after shifting...normal? ecuflash fix?

More questions to come, I'm sure.

Thanks for all the great help guys! I couldn't have come this far without the help of the great minds on this wonderful site. :bowdown: :bowdown: :bowdown: :bowdown:
 

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stupid booster
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1. yes it goes lean and there is a delay
2. not sure what u mean
3. the flutter sound is becaue its being recirculated. i have the same thing
4. not sure what u mean again. Normal driving it will sit around 14.5 - 15. giving it gas or letting off will change the af alot at first because there is a delay.


What are u using for tuning?
 

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Stage 1 SDS @11+ psi
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1. When you let of the gas to decelerate, your car goes into open loop and cuts the fuel. You should go max lean there (21.0:1 is the leanest on my AFR), always.

2. Do you throw any misfire codes or any other codes for that matter? You may want to check your FPR.

You really need to data log to find what your LTFTs are really doing.
 

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Discussion Starter · #4 ·
Tuning with an eManage blue

2. No codes yet, knock on wood. I, uh...don't...have an fpr....installed yet. I didn't install the wally 255 either. Russ said that at 6 lbs I'm ok for now.

suggestion for good datalogging?
 

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Stage 1 SDS @11+ psi
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Discussion Starter · #6 · (Edited)
370cc RC Engineering (thanks to snipershark)

I assume the evoscan use's the tactrix cable...

4. icemanrld19, If I keep my foot on the exact same tps for an amount of time it will stay around the same afr. As soon as I let off slightly the afr jumps lean(16+) then rich(11-) then back to around what it shoud be. Same goes for pressing on the gas just a little the afr goes rich(11-) then lean(16+) then what it should be....ish. But if I hammer the gas it goes right to what it should be and sits there...if that puts me into boost the afr is about 11.2-11.5 and doesn't move until I shift or let off. Maybe I'm just paranoid...?
 

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Stage 1 SDS @11+ psi
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I haven't heard it... One way to ensure you are not getting surge is to take off the recirculation hose, have someone rev your engine (as to hit boost), and see or feel the air come out of the BOV when the gas petal is released. If the BOV is working, you won't get surge.
 

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repforenzo said:
I haven't heard it... One way to ensure you are not getting surge is to take off the recirculation hose, have someone rev your engine (as to hit boost), and see or feel the air come out of the BOV when the gas petal is released. If the BOV is working, you won't get surge.

also if you run a 3' exhaust for example and your running relativley low boost; there is not enough pressure pushing the exhaust air and it would rather go back throguh the turbine after you let off the throtle. (or so i read)
by all means, correct if wrong.
 

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Zed oh six
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WanderingPinoy said:
Anyone have a sound clip of compressor surge, for comparison?
There was a video going around of a 2G on a dyno that was surging. i cant find it though.

Some turbo kits out there dont even have BOV's for low boost applications. There is a kit by XS Engineering for the MR2 Spyder that pushes 7psi with no BOV, and I have seen a few other one-off kits with the same design.
 

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Stage 1 SDS @11+ psi
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icemanrld19 said:
Not sure what you mean by surging. Please explain. Are you trying to get a sound clip on how the BOV sounds?
You know... Compressor surge: When you close the Throttle plate while the SC/Turbo is still boosting. The boost has nowhere to go, so it goes out the path of least resistance. More often then not, that path is back through the turbine in the opposite direction. Puts a lot of stress on the turbine's bearing and blades.

Like Rulez said, most turbines are designed to handle a bit of compressor surge, but that is for low boost apps.
 

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Stage 1 SDS @11+ psi
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icemanrld19 said:
isnt that the reason for a BOV? To release that surge.
Yup. But if the BOV is faulty or setup incorrectly, it could cause some run issues that may not be related to surge.

How is your BOV set? Set more to 'hard' or 'soft'.
 

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Resident Asshole
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360 degree thrust washer. It doesn't protect against surge perse but it is to try and help the turbo last longer.
 

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Resident Asshole
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Different BOV's sound differently. Certain BOV's are designed to flutter.
 
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