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Discussion Starter #1
ive read loads of posts about this, across various sites, and none of them are clear, as what to do. most of the treads are old, and missing pictures, and the descriptions arent very in depth.

is it just a case of unplugging everything from the back of the engine, vacuum box, and boost conroller, and linking the turbo and FPR, to the intake, with a T ?

i came across this picture in google.
is it correct ?

everyone says its well worth doing, as it resolves some running issues, and smoothes out the boost across the rev range, as well as giving extra boost in 1st and 2nd.

22510
 

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I would disagree with those that say it will resolve running issues (unless the rear solenoid valve is the fault), or smooth things out. If you are just looking for more boost in first and second (if you can use it in a FWD drive car), then the correct way to adjust it is in the map ideally. If you are all about full throttle, and not too worried about part throttle regulation, then go for it as it does simplify the set up.
But it will effect how the car feels on part throttle/part boost, and when you come off the throttle. I have a Z20let in a RWD car, so for me the part throttle response is fairly important.
 

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I would disagree with those that say it will resolve running issues (unless the rear solenoid valve is the fault), or smooth things out. If you are just looking for more boost in first and second (if you can use it in a FWD drive car), then the correct way to adjust it is in the map ideally. If you are all about full throttle, and not too worried about part throttle regulation, then go for it as it does simplify the set up.
But it will effect how the car feels on part throttle/part boost, and when you come off the throttle. I have a Z20let in a RWD car, so for me the part throttle response is fairly important.
i rarely rag on it. i drive in the mid range most of the time. i dont like to punish my cars on the redline.
its not boosting quite right tho, and it has a very slight misfire, once every 10 seconds or so, so i thought it might be worth trying out, to see, as i cant find anything up with it.
it would probably benefit from a dyno run, to see whats going on, but im broke at the mo, so cant do that.

at 1400 kg, it is one of the heaviest cars ive owned tho, which makes it difficult to judge whats normal, with all that extra weight behind it.

could be something to do with the turbo tho, not sure. i need to check for bearing play, and actuator pressure, and any cracks in the manifold, etc. the solenoid could be at fault, as you mentioned.

i dont have much experience with turbo's, and all the extra parts, sensors, vacuums, etc, makes things harder to diagnose.

rwd zlet, nice, whats that in ? sounds interesting.
 

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Well I guess the rear BCS delete costs nothing to do really, and can be done/undone in about 5 mins. If nothing else you could try it to see if it helps with your misfire, then just put back if it doesn't help. A slight and occasional miss (as long as it's only at idle) is fairly common on these engines and can sometimes be a pain to pin down. Lambda sensor, AFM, a poor earth near the battery (earth mod) can be the culprits, but there a few other suspects too. I finally sorted mine after a head rebuild!

I have a Z20let in a VX220, so that keeps thing interesting in the bends if the boost spikes mid corner..
 

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Discussion Starter #5
Well I guess the rear BCS delete costs nothing to do really, and can be done/undone in about 5 mins. If nothing else you could try it to see if it helps with your misfire, then just put back if it doesn't help. A slight and occasional miss (as long as it's only at idle) is fairly common on these engines and can sometimes be a pain to pin down. Lambda sensor, AFM, a poor earth near the battery (earth mod) can be the culprits, but there a few other suspects too. I finally sorted mine after a head rebuild!

I have a Z20let in a VX220, so that keeps thing interesting in the bends if the boost spikes mid corner.
yeah, the misfire is only at idle. through the rest of rev range, it seems fine.
i had a fault on opcom, for lambda no.1, by the manifold, which i replaced, hoping it would remedy the issue, but hasnt changed anything unfortunately. comp tested all cylinders at 160, so im fairly certain the valves are sealing properly.
anyway to check the AFM ?
i will check the earths by the battery too, thanks.

you talking about the head rebuild ... a while back, i bought - victor reinz 1 piece stem seals, head bolts, and gasket kit, so if need be, i could pull the head off, to do the stem seals.
from what i understand, they fail on these engines after so many years, and its 15 years old now, with 79k on it, so probably worth changing.

i totally forgot about the 220. very cool car, and rare to see, these days. (y)
 

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If you don't have another AFM to try, you could do a basic check by seeing if the car runs better, or worse with it unplugged. It will obviously log a fault code, but it should run worse once unplugged if the AFM is working reasonably well.
If you have the time to do the head re-build, its well worth it. I also did some moderate porting while the head was off, before grinding the valves back in and it did free up a few more ponies for free.
 
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