RPMs spike during up shifts
#1
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RPMs spike during up shifts
I've been chasing this issue for a little while. The car is running good and idles well but when I am up shifting, once I put my foot on the clutch the RPMs will jump a few 100 RPM. Doesn't really make shifting smooth. I've been trying to sort it myself but can't seem to resolve it. Anyone have any suggestions? Short log and tune below.
Details of the car. 1997 Miata. MS3 Pro pnp. BRP MP62 supercharger, 75mm throttle body, over the radiator fed intercooler. 640cc Flow Force injectors, DW200 fuel pump. Also the IACV is from an NB mounted to the dummy throttle body.
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Log
Details of the car. 1997 Miata. MS3 Pro pnp. BRP MP62 supercharger, 75mm throttle body, over the radiator fed intercooler. 640cc Flow Force injectors, DW200 fuel pump. Also the IACV is from an NB mounted to the dummy throttle body.
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Log
Last edited by scottns; 07-05-2020 at 08:19 AM.
#3
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Throttled volume. Basically when you close the throttle, there is still a large volume of air in the piping/intake manifold that the MAP sensor reads so the ECU will inject fuel for it, so when you press the clutch in, there's no load and the RPMs rise. The only way to solve it is to enable fuel cut whenever you press the clutch in above 1600rpm or do the dual throttle body mod.
#4
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Throttled volume. Basically when you close the throttle, there is still a large volume of air in the piping/intake manifold that the MAP sensor reads so the ECU will inject fuel for it, so when you press the clutch in, there's no load and the RPMs rise. The only way to solve it is to enable fuel cut whenever you press the clutch in above 1600rpm or do the dual throttle body mod.
#5
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If you understand how the IAC valve works, then you will realize that it simply does nothing when mounted on the dummy TB unless the dummy TB has an inlet port for the IAC (unlikely as it has to work with the stock MAF for those with the stock ECU). This is not the source of your problem however it may fix idle issues.
#6
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If you understand how the IAC valve works, then you will realize that it simply does nothing when mounted on the dummy TB unless the dummy TB has an inlet port for the IAC (unlikely as it has to work with the stock MAF for those with the stock ECU). This is not the source of your problem however it may fix idle issues.
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