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Old 04-30-2011, 08:59 PM   #61
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what're you comparing the performance below 5000 RPM to when you say it doesn't have power?

One thing to try is to set your boost target table to all the same value except for the bottom 0%TPS row. That'll make sure boost builds when you are on the gas. If you look at the log you posted, you're at part throttle for part of that initial gear pull and your boost map is limiting you at part throttle. Worth a look.

Also, if you've done anything with your timing belt, it could be retarded a tooth but that's a later test after the easy stuff is ruled out (and I believe you can verify cam timing with the VVT code but I'm not sure--I will think on it)

Also try removing and plugging the VTCS vacuum line to rule that out as a possible blockage. It's the one with the one way valve under/behind the throttle body. looks like a wastegate actuator. just plug the hose you pull off the actuator. You probably wont notice this.
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Old 05-01-2011, 12:21 PM   #62
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whats the question?
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Old 05-01-2011, 08:03 PM   #63
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Quote:
Originally Posted by y8s View Post
what're you comparing the performance below 5000 RPM to when you say it doesn't have power?

One thing to try is to set your boost target table to all the same value except for the bottom 0%TPS row. That'll make sure boost builds when you are on the gas. If you look at the log you posted, you're at part throttle for part of that initial gear pull and your boost map is limiting you at part throttle. Worth a look.

Also, if you've done anything with your timing belt, it could be retarded a tooth but that's a later test after the easy stuff is ruled out (and I believe you can verify cam timing with the VVT code but I'm not sure--I will think on it)

Also try removing and plugging the VTCS vacuum line to rule that out as a possible blockage. It's the one with the one way valve under/behind the throttle body. looks like a wastegate actuator. just plug the hose you pull off the actuator. You probably wont notice this.
I'm comparing it to itself above 5000. It's like a lightswitch. The sound changes and everything. One theory somebody had today at the autocross (non-miata person, but I haven't read anything about how the VVT works yet so I went with it) was that the oil pressure at that RPM overwhelms the solenoid and the cam moves or something.

I'm not using EBC yet. I have the solenoid on my desk, but I'm using a MBC for now. I didn't notice that EBC was turned on until Friday, when I turned it off.

I haven't done anything with the timing belt yet. I will probably replace it later this summer, as it's getting close to 60k miles and I have a new one and it needs new belts anyway.

I'll try plugging that line and see what happens.


Brain: The question is what is changing around 5000rpm to cause a feeling of "hitting vtech, yo"?
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Old 05-01-2011, 10:05 PM   #64
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I checked and plugging that vacuum line doesn't change anything.
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Old 05-01-2011, 11:12 PM   #65
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I seriously doubt the VVT is doing anything but you can unplug it too and it will stay at max retard.

At full retard, my car is sluggish below 5 grand also. but not light switch sluggish. just down about 30-40hp (max) in boost and it tapers back up to normal by 5k.

If you can safely accomplish this: try running a 2000 rpm pull up to 6000+ in 2nd or 3rd gear and log it. any sluggishness should show up in the RPMdot trace. above 5000 in my car on a recent log, it was fairly steady between 40 and 400. Lower gears will be noisier and slightly higher probably. You might have to set the max and min for rpmdot in megalogviewer to like +/-4000 to make things appear less noisy.

have you checked all your intake piping for leaks?
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Old 05-15-2011, 12:31 PM   #66
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I have checked the pipes for leaks, but I keep forgetting to make a log of a 2-6k pull. I did grab another piece of data by accident yesterday. I forgot to switch my spark back to the table after setting it, and I still get a solid change at 5000ish rpm when spark is set to 10*. The exhaust pops and snaps on decel too (overrun was off). If I get an afternoon without rain this week I'll try to get that log and try unplugging the vvt.
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