74Adam Posted June 26, 2015 Share Posted June 26, 2015 Has anyone done this and then successfully calibrated the TPS? I used the mounting plate from the 280 TPS to mount the 240 TPS. The "D" in the shaft is rotated differently so you have to take that into consideration when you drill the holes, which I did but even with the available adjustment I can not get the TPS calibrated and I'm wondering if I have overlooked something really stupid. BTW, the 240SX TB has been on the car and runs so the TPS itself is fine and, yes, if I can't get this figured out I can just put it back on so this isn't critical. Using the stock throttle body is just a preference thing. thanks Quote Link to comment Share on other sites More sharing options...
dexter72 Posted June 27, 2015 Share Posted June 27, 2015 Unless you have a Standalone setup, you cant use a 240sx TPS on your engine.. The 240sx is a Potentiometer style TPS, like mostly all 90's and newer Nissans. 280z is basically an on off TPS. Quote Link to comment Share on other sites More sharing options...
74Adam Posted June 27, 2015 Author Share Posted June 27, 2015 Yes, it's a megasquirt setup. Quote Link to comment Share on other sites More sharing options...
NewZed Posted June 27, 2015 Share Posted June 27, 2015 So what are you seeing that's different between the two? Sounds like you think it's a clocking problem, since you mentioned drilling holes. There's a whole calibration procedure described in the Megamanual. Quote Link to comment Share on other sites More sharing options...
74Adam Posted June 27, 2015 Author Share Posted June 27, 2015 No, it's not that I don't understand the calibration procedure, I've calibrated the TPS for the 240SX. All I meant by "drilling holes" is when you use the mounting plate of the original 280 TPS you have to drill new holes because the mounting ears are spaced differently between the two. Fortunately, the spacing of the 240SX TPS is smaller therefore there is actually enough room on the 280 plate to mount the TPS from the 240. Anyway, what's happening is that I can set the closed and open values but when I start the car the TPS value doesn't stay on zero at idle. It "bounces", not much, maybe between zero and six or seven. Of course, this triggers the accel enrichment which obviously isn't going to work. And the throttle blade is completely closed at idle - air is only coming in through the bleed screw. Sorry, I should have been more clear in my original post. Quote Link to comment Share on other sites More sharing options...
dexter72 Posted June 28, 2015 Share Posted June 28, 2015 See what changing the tps value to 6, at fully closed does. I don't think accel enrichment will turn on. Example, I have a 2jz in my 260z, using a Toyota throttle body. It would show 3 while my engine idled. So i just increased the closed number in megasquirt until it showed zero. I have No accel enrichment at idle Quote Link to comment Share on other sites More sharing options...
74Adam Posted June 28, 2015 Author Share Posted June 28, 2015 I figured out what the problem was.......ME! And really, I'm not that surprised :-/ Ok, I didn't realize that when you have unbolted a TPS from the throttle body that you have to actually measure the voltage on the wires and get the closed value between 0.45 and 0.50 volts to get it working when you reinstall it. It just thought megasquirt took a reading at two points and that was it. So, I wasn't even in the ballpark as far as adjustments. I got on youtube and found a video of someone doing this calibration and realized that was the problem. So, I went to Oreilly and got a multi-meter this morning and figured it out just now. Anyway, sorry for being stupid and I appreciate the help Quote Link to comment Share on other sites More sharing options...
LanceVance Posted June 28, 2015 Share Posted June 28, 2015 I figured out what the problem was.......ME! And really, I'm not that surprised :-/ Ok, I didn't realize that when you have unbolted a TPS from the throttle body that you have to actually measure the voltage on the wires and get the closed value between 0.45 and 0.50 volts to get it working when you reinstall it. It just thought megasquirt took a reading at two points and that was it. So, I wasn't even in the ballpark as far as adjustments. I got on youtube and found a video of someone doing this calibration and realized that was the problem. So, I went to Oreilly and got a multi-meter this morning and figured it out just now. Anyway, sorry for being stupid and I appreciate the help So post how to do it for the next guy! Quote Link to comment Share on other sites More sharing options...
74Adam Posted June 28, 2015 Author Share Posted June 28, 2015 Oh, I figured I was the only weirdo that still wanted to use the stock throttle body with megasquirt. Or, do you just mean the measurement procedure? Quote Link to comment Share on other sites More sharing options...
LanceVance Posted June 28, 2015 Share Posted June 28, 2015 I'm personally interested in the calibration procedure. That said, I've found solutions to problems unique to my build through posts in seemingly unrelated topics. You never know who you'll help down the road, but it only happens when we contribute. Post it all! Quote Link to comment Share on other sites More sharing options...
NewZed Posted June 28, 2015 Share Posted June 28, 2015 I got the impression that the TPS should have a value at closed throttle and that MS is then calibrated to that value. In other words, you would tell MS that "6" is closed, and that whatever value the TPS puts out at wide open is 100%. Most sensors always put out a signal and the control system is calibrated to what you want those values to mean. Quote Link to comment Share on other sites More sharing options...
74Adam Posted June 28, 2015 Author Share Posted June 28, 2015 See, that's what I was assuming would happen which is why I wasn't worried about not getting the TPS mounted EXACTLY on the same rotational position on the throttle shaft of the Z TB relative to the SX TB. But, at least for me, it didn't turn out to be so simple. That's ok, now I know how to use a multi-meter...lol. Listen, I'll do a short write up when I have a little time. What I cobbled together isn't "easy on the eyes" but it works. Quote Link to comment Share on other sites More sharing options...
Namor Posted June 28, 2015 Share Posted June 28, 2015 (edited) I had this issue but haven't even really started tuning my car yet. I just went and tapped off the sensor return and TPS wires to measure voltage, and then clocked the TPS with the throttle closed until I got into the band you stated and tighten it down. It's rock steady now. I'm curious why this isn't in any of the megasquirt documentation because it doesn't seem like it is equipment specific. See, that's what I was assuming would happen which is why I wasn't worried about not getting the TPS mounted EXACTLY on the same rotational position on the throttle shaft of the Z TB relative to the SX TB. But, at least for me, it didn't turn out to be so simple. That's ok, now I know how to use a multi-meter...lol. Listen, I'll do a short write up when I have a little time. What I cobbled together isn't "easy on the eyes" but it works. I think I spoke too soon. When running, it fluctuates which I think is due to a ~.1v ripple in the 5v supply. I'm not sure what can be done about that. Edited June 28, 2015 by Namor Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted June 29, 2015 Share Posted June 29, 2015 (edited) The tps wires should be shielded. If you look at a 240sx engine harness you'll notice the tps wires are shielded. Edited June 29, 2015 by skirkland1980 Quote Link to comment Share on other sites More sharing options...
dexter72 Posted June 29, 2015 Share Posted June 29, 2015 I know for stock nissan vehicles with factory computers you need to set up the tps correctly. But i don't really think you have to have it exact for a Megasquirt setup. I mean unless your multi meter shows the numbers going in the negative when opening the throttle plate, then going positive at some point before fully open. Using the multimeter to check tps sensors is always a good thing. All you need to do is measure the resistance fully closed, then at fully open. Input those numbers into megasquirt or let megasquirt do it for you. I have swapped over 2 seperate Nissan tps sensors onto my l28 engine. And now have done the same with this Toyota engine setup. All of them worked fine this way. I may be swapping this Toyota throttle body out and using a Ford one at some time. Going to use the same procedure, closed and open value inputs into Megasquirt. Quote Link to comment Share on other sites More sharing options...
Namor Posted July 2, 2015 Share Posted July 2, 2015 The tps wires should be shielded. If you look at a 240sx engine harness you'll notice the tps wires are shielded. While shielding may help, others have not had this issue and it would have done nothing for me. As it turns out, mine was due to my wideband sensor. I guess when i saw it stable it was already up to temp and wasn't cycling the internal heater. When it was heating up, the ripple existed even when I measured only the 5v supply with no sensors attached to it. Once I grounded it to the same ground the ECU uses, then the ripple was completely gone and TPS/MAP readings were rock steady. Quote Link to comment Share on other sites More sharing options...
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