VSS...Does it matter?

K-Series Programmable ECU installation questions / support issues
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AWH
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Joined: Sun Dec 13, 2009 7:50 pm

VSS...Does it matter?

Post by AWH »

Greetings,

Just got my KPro and am doing some basic street tuning off a base map until my favorite dyno shop comes back on line (they've had to move). One thing I noticed is that my VSS signal is quite erratic. I'm fairly certain this is due to a sticking speedo cable, as I also see a little bit of bounce in the speedo display itself.

So the question is, does it matter if the VSS reading is screwy? Car is NA and I don't see anything in the calibration that is speed related, but I may have missed something.

Attached is a datalog showing the VSS bounce. I've also attached the KAL, for reference. Car is an EF hatch with an ITR K20A swap using a rywire harness, and uses the original cable VSS.

TIA,

--Andy
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Spunkster
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Post by Spunkster »

It is either a cable problem or a problem with the seedometer in the cluster as that is where the VSS is located. This should be fixed.
AWH
Posts: 15
Joined: Sun Dec 13, 2009 7:50 pm

Post by AWH »

Spunkster wrote:It is either a cable problem or a problem with the seedometer in the cluster as that is where the VSS is located. This should be fixed.
For sure, I do intend to fix it. And I'm pretty sure it is the cable not the speedo, since the needle wavers on two different speedos I've had in there (one with a tach and one w/o).

But...does it matter to the KPro? Is there anything that depends on the calculated speed/gear?

Today I did find a gear-based ignition compensation which had some values in it for the baseline kal I used (ITR, Toda intake/header, etc.) and so I zeroed that out for now. Anything else?

--Andy
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Spunkster
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Post by Spunkster »

There are compensations and VTEC also needs a good vss input.
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