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Discussion Starter · #1 · (Edited)
So I've been thinking for a while about why my car is not as fast as I know it has been. :lol: I know we'd all like to think our cars are faster than what they are but hear me out.

About a year ago or so I first learned how to tune use PFC with FCedit from another member on here whos has a turbo 2zz spyder. He helped me tune WOT and we did those in fourth gear on a closed circuit, late at night. :lol:
At that time the car was a rocket (15-17lbs of boost on built 1zz). Even in fourth gear when the revs got close to, I would like to say 5-6k, it was like I hit Vtec on a Type-R in third (for those thats felt this it equals joy). Like i'm hitting lift at 70-80mph (whatever the mph is at that rpm in fourth). I'm running a Rotrex supercharger so as the rpms goes higher the higher the boost as well. Funny thing was we also tuned his car that same night and his car felt EXACTLY the same as mines when it hit lift and boost at slightly higher rpms of course. I know because I was driving both cars and he passenger for tuning.

Nowadays, again I was tuning WOT, hitting the same boost levels in fourth the car kinda falls on its face vs before. Dont get me wrong its still accelerating but theres no more that Vtec pushed into the seats type acceleration. Mid range is great 3-5k, actually better than before but now once it hits 5k seems like it thinks about accel faster but doesn't.

It just dawned on me today that maybe my VVTi is not functioning correctly? Would VVTi have this much effect on my power level? I'm running PFC, downside to that is not having any cel codes. Also I'm not proud to say I have not tuned the VVT map in PFC even thru multiple revisions of my map reference numbers because I don't know how to. So obviously the numbers are shifted and probably off for WOT but would it cause such a big disparity in HP? I'm thinking from seat of the pants feel I've lost a good 30-50RWHP.

Sorry for being so long winded.
 

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So you were experiencing something like Lift on a 1zz? Torque of a 1zz rotrex is pretty flat, I don't think you're supposed to really feel any sudden surge of power top end. If your VVT isn't working, you won't feel power mid range, because that's what VVT was designed for.
 

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Discussion Starter · #4 ·
You havent tuned the VVT ? Makes big difference.

Havent you put her on a dyno ?
The one time it was on a dyno for tuning the tuner said there wasn't much to gain there or something to that effect. Basically he was a crap tuner for this platform and the PFC.

So VVTi only helps in the mid range?

I definitely felt a big surge in power up top just like my friend's 2zz turbo. Is there a way to check if its working correctly?
 

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Is there a way to check if its working correctly?
You can run 12 volts directly to the control valve and the cam should shfit causing the engine to stall. Or you can run a dyno plot in copilot and just change out the vvt settings after a base run. Do a base run then flatline all the vvt settings to 50 and do it again, If vvt is working you will see a horsepower drop/rise depending on where in the rev band you are.
 

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I agree

I would be looking at something else wrong with the tune or possibly the BOV.
My Rotrexed 1zz is steady power off idle, there is no surge in power just pulls hard right through the power till red line, very steady pull. perhaps your BOV is letting off boost when it shouldn't be and then closing up allowing the full boost of the S/C to give you the sudden surge in power. I also have a S/C on my Tundra and again it's a pretty steady pull of power, it does have a slight surge at 3500 but its a twin screw type of blower, not a rotary style. Hope you figure it out.
 

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Discussion Starter · #14 ·
I have a boost gauge, theres no leak or surge of boost in the upper rpms. Power is steady and increasing just towards the end it gets way more.

I'm thinking the explanation of VVT settings are off up until that part where maybe its right and power is more. But now it doesn't do it anymore so I wonder if the VVTi is actually working.

Will try pulling ocv plug while idling to see if it does anything.
 

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Not sure if the way to test this is similar like on the VVTL-I on the 2zz but I was reading something on it yesterday and read this thread again. If I can remember I'll try and look it up. I think it was similar to what Blackcreek mentioned except I think there was an Ohm Meter involved.

I'll browse the BGB for the Mr2 as well. Yeah I definetly know what you mean about the, "Oh snap!" factor, I would think it would be real noticeable in your car. Scary Fast is all I can remember.
 

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I am only running a stock NA 1zz but I do notice a bit of kick at about 4k when accerating hard. I believe VVTi allows the best of both worlds between low end torque and hi end power.
 
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