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So I was having the jerky hesitation problems that many have reported, but the car would never throw a DTC. Mine would occasionally stumble only when cold and only between 2500-3000 rpms. After it warmed up it was fine. I checked TPS V at idle and WOT, MAP, PHOS, every piece of the secondary air injection, plugs, coils, fuel - all checked fine. Finally I checked the TPS again, but this time I slowly rotated the sensor and monitored the voltage - found a ratty section that was very unstable. So now I start looking for a new TPS, but you have to buy the whole throttle body . The local dealer wanted $550, and majestic (online) gets $476. That's alot of coin for a 0-5V potentiometer. So instead I bought an OmniPower TPS for $75, and buzzed off the flanges so that I could rotate it to .30V at idle. Works great and voltage at WOT is correct also.
UPDATE: Omni Power now has a TPS that fits the S2000 directly - no need to cut off the plastic flanges now.
Here are the details on throttle position sensor adjustment and replacement - use at your own risk.
The throttle position sensor (TPS) is on the left side of the throttle body. The TPS is a potentiometer that provides a .30 to 4.5 volt working output range to tell the ECM the throttle butterfly position. To check your TPS, connect a voltmeter or multimeter (DC volts setting) and measure the voltage across the red/black wire and green/yellow wire. The TPS must be plugged in, and the ignition is on. Remove some insulation from the red/black and green/yellow wires. The throttle is to be left in the "idle" position, so don't pull on the throttle cable. Turn the ignition on (but car engine not running) and touch the black (negative) probe of your meter to the green/yellow wire, while also touching the red probe of your meter to the red/black wire. The reading should be in the vicinity of .30 volts. Now do the same thing, except rotate the throttle wide open - the reading should be in the vicinity of 4.5 volts.
Adjusting or replacing the TPS is more involved but can save you a wad of cash. The TPS is mounted with (2) diabolical m4 tamper-proof 5 point screws. An easy way to remove the screws is to dremel grind slots in them so that a screwdriver can be used. You will need to remove the throttle body to do this. I replaced my screws with m4 socket head screws. After you replace the screws you can adjust your TPS by loosening it and then rotating it while you are watching the idle voltage level as described above.
To replace the stock TPS with an OmniPort, you will need to buzz the flanges off the OmniPort to allow it to rotate CCW enough to adjust to .30 volts at idle. Use some thick washers to clamp the TPS in place after you get it adjusted. Mine has not moved after many miles. You could also use servo clamps to hold the TPS.
saved about $420!
UPDATE: Omni Power (omnipowerusa.com) has a TPS that fits the S2000 now, TPS flange mod is no longer needed.
Thanks for your writeup! I'm having some trouble getting my omni tps set correctly in my Skunk 2 tb. How much further past the original adjustment slots did you end up rotating your tps once the flanges were cut? Also, how did you re-insulate the wires once it was set? Finally, did you use a gasket when you installed the sensor? Thanks.
04-22-2008, 01:16 PM
Throttle Position Sensor Jacked?
. The local dealer wanted $550, and majestic (online) gets $476. That's alot of coin for a 0-5V potentiometer. So instead I bought an OmniPower TPS for $75, and buzzed off the flanges so that I could rotate it to .30V at idle. Works great and voltage at WOT is correct also.
nice work, can you post pics of yours installed.
