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Discussion Starter #1
My 2000 green insight developed a very mild case herky jerky. I cleaned the egr plate and valve (just the bottom). Both were pretty clean already and more cleaning did not resolve the issue. The car only has 127,000 mi on it. Then, driving to work, the car shuttered a little and the check engine light came on, auto stop and charge and assist lights stopped working although the car seemed to get both charge and assist. Autostop and the charge and assist lights came back when I went to drive home but the ce light was still on and odd driving behavior of the car was unchanged. It seemed to never go in and out of lean burn, like it was in some kind of limbo state, though I still got good mileage. I got a po122 "throttle position sensor circuit low voltage" code. I don't see any obvious problems with the wiring, doubt that is the problem, and am not that competent to do all the testing. So I'm going to replace the tps based on the discussion here. My problem is, how do you get to the damn thing? I'm thinking of pulling the throttle off and working on it that way. It appears to be held on by four bolts. How little can I get away with not disconnecting? Or is there a better way? Could someone provide me directions for dummies?

Any and all suggestions are most welcome.
 

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Discussion Starter #3
I found the TPS calibration to be very tricky. I had to have the throttle body half out to get to the bolts holding it on. The TPS is very sticky and does not move smoothly. When I finally got it to .48 and the bolts tightened down it decided to go to 4.77 and stay there. So I left it there. When I checked it at WOT the voltage was 4.22, which is too low. The honda-tech.com instructions (DIY How-to: Calibrating the Voltage on your TPS Sensor - Honda-Tech - Honda Forum Discussion) posted in another thread here on this issue says to adjust the TPS at WOT first and then adjust the voltage at idle by adjusting the throttle stop screw. Someone on that IC thread said that the honda-tech thread had been corrected but did not the url for it. All the other videos I can find on TPS calibration just set the idle at .5 and the WOT always ends up being 4.5. Some discussions say to calibrate with the engine warmed up, which I did not do.

Any suggestions for calibrating my TPS? How to I get both WOT and idle correct when just setting the TPS at idle doesn't work.

Thanks for help!
 

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Discussion Starter #4
So I tried the honda-tech.com directions mentioned above a set the TPS voltage to 4.48v at WOT. But it changed its mind and decided to settle in at 4.46 or 4.45 or something like that. I then tried to set the TPS volts at idle. I ended up turning the throttle position screw all the way down and that gave me .499, which then decided to become 5.01 or .02. I was not going to modify the throttle position screw or plate. So I put everything back together a took a test drive, and than another test drive after remembering to tighten the clamp holding the air hose to the throttle body chamber. Code is gone and I got 86.7 mpg over about a twenty-mile course that is pretty flat and slow (45 mph speed limit) on a cloudy day around 60 degrees. That's almost a record for me.

My conclusion is that this is not too hard to do and really helps performance, but it really should be done on a bench. One of you guys with a good shop and a lot of know how should set yourself up to replace and calibrate throttle position sensors. If you could run 5 volts to the tps plug, you could get a very precise calibration, like they do at the factory. This is almost an upgrade or mod and well worth doing, particularly if you get a PO122 code.
 

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Thanks for the input and feedback. Great price for the part as well.
Let us know how it holds up long term.
 

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I need to do this! I've had a new TPS on my desk for months. Thanks for the write-up. How important is the WOT voltage? I don't plan on messing with the throttle stop screw unless WOT is way off with the idle voltage correct. According to the factory service manual, it's about 0.5v at idle and about 4.8v at WOT.

No TPS codes for me, but I have a bad part throttle bucking and trouble staying in LB.
 

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Discussion Starter #9
WOT voltage is just as important as voltage at idle. You could try setting the voltage at idle first and then checking it at WOT. If that works, great. But that didn't work for me. So you may have to or just go ahead and set it at WOT first and then adjust the voltage at idle by fiddling with the idle adjustment screw. That should not put you off. After all the dismantling and adjusting (I also tightened the throttle cable, which was very easy) everything, fiddling with the adjustment screw is a breeze. It is a small screw with a 2.5mm hex head held tight with a 7 mm bolt, if memory serves (both odd sizes. Who decides these things?).

I'd really like to know if this fixes your your bucking and LB problems.
 

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My concern isn't about difficulty. From what I understand, the throttle stop screw is adjusted to allow the throttle plate to fully close with sticking/binding. There's another screw for adjusting idle speed, but it won't do anything for TPS voltage.
 

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Discussion Starter #11
Right you are. My bad. I meant throttle stop screw, not the idle adjustment screw. I'm with you. Don't fool with the idle adjustment screw. Backing off the throttle stop screw will lower the idle tps volts. Start with setting the WOT TPS volts and then set the idle TPS by adjusting the throttle stop screw. At least that's what worked for me.

I went on a much hillier ride on a much cooler day (47F) today with some city driving and a stretch of 65 on the the freeway and, even being very careful on the rural road home (not a lot of traffic - a lot of people staying home), I could only squeeze 77.3 mpg out of it, which is still better than usual and I would have expected. So I still think this is worth the effort.

Cheers.
 

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Discussion Starter #12
84778

One last idea: take your old TPS and dremel/cut it until it looks like this. Then you should be able to use it to run leads from your TPS plug to your newly installed TPS on the throttle body while it's out of the car and do all your measuring and adjusting there. That's what I'm going to do next time.
 

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With Honda throttle position sensors, the usual route is to loosen the throttle-stop enough to prevent it touching the butterfly, calibrate the sensor to its "closed" voltage (generally 0.45 volts, SOME honda's do have this specifically different), and then adjust the throttle stop per honda OEM instructions. I personally adjust it just enough to crack the throttle partially open to prevent it sticking shut, about half a turn or so. This is generally where you find with OBD2 scanner data that your throttle, even fully "closed" reads anywhere from 3-15%

Your low range of the TPS is more important to have calibrated properly than full throttle. Part throttle is all about drivability. The only thing that happens during wide open throttle is the ecu yanks some ignition timing and adds a ton of fuel enrichment. Beneficial to those who beat the snot out of their cars, but they generally are the type to not worry about a car bucking wild at low rpms and higher load.

As with anything around a throttlebody getting moved, you may have to adjust your idle screw. On the Insight, it has a plug to be removed to access it, and with any sort of "while you are in there" approach, now is a good time to fully remove it, verify the rubber O-ring is in good condition, clean it with hot soapy water, clean the idle screw's hole with carb cleaner, let dry, and re-install idle screw. Bottom it out carefully, then back it off 2 full turns as a rough starting point.

Most honda's will have you adjust idle by unplugging the IACV, adjusting the idle to 450-500 rpms, trhen plugging IACV back in, all this with the service jumper in place.
 

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Discussion Starter #16
Wow. Thanks M Liston. I did not know all of that. Perhaps I could have just lived with 4.22 volts at WOT. By setting the WOT first, however, I got both idle and WOT to specs, and I couldn't do that the other way around. Still working fine, though I'm going much of anywhere.
 

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Getting both to specs is hard for most, so a pat on the back regardless of the method of the solution.
 

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I'd really like to know if this fixes your your bucking and LB problems.
For me, the new TPS made no difference at all. The Honda service manual says the TPS values should be "about" 10% at idle and "about" 90% at WOT. I used my ScanGauge to set the idle at 10% and the WOT value ended up at 86%. Close enough.
 
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