TPS adjustments, unclear on voltage readings.

Nathaninwa · 06-18-2011, 03:06 AM

Long story short....new registered member, but not at all new to the Supra/7m series engine scene. There is so much info that searching can usually find what I need. About 3 years ago I installed a 7m into my trail truck with a Cressida harness and ECU. Got it running and more or less drove it, but has always felt like its been down on power. So recently I have installed an 87 MT supra ECU, made an adapter harness from the old style plug to the newer style grey plug by sacraficing a spare ecu I had. Now I am going through and verifying all the info i can. Ive come down to the TPS....NSW/AC....and the speed signal

My questions.....does the ECU need to have a NSW signal and an A/C signal, or will this just pop a code 51?

Does the ECU use the speed sensor signal for any fueling/timing adjustments?

And I have adjusted the TPS according the to the online TSRM ( http://www.cygnusx1.net/Supra/Librar...spx?S=FI&P=101 ), and all is within ohm spec at all points. But when it comes to checking voltages I have a problem. My information comes from ALLDATA. 87 supra 7mge should read 4-5 volts at wot on VTA, and I get 3.6 volts, no matter what tps number I am using. And I am supposed to get 10-14 on the IDL pin at WOT and I get zero.
In reference, the 1990 Cressida ecu wants 3.2-4.2 at the VTA, and 4-6 volts on the IDL pin.

I can adjust the tps to read 4.1 volts at WOT before the voltage drops out to zero, but then idle is way off....and neither option gives me 10-14 volts on the IDL pin.

I have not tested the Cressida ECU, only the Supra as I am wantring to get away from the auto ecu setup, and possible power downage from improper inputs on the tranny side, and possible no VSS signal.

Im working some other kinks on the truck before I can drive it, just wanting to solve the voltage questions on the ECU before I button it all up.

Nathaninwa · 06-18-2011, 03:41 PM

I should say that the truck does run....had a 51 code when I first started it, then when I was tweekin I was checking the VF voltages and tracking the afr with a narrow band guage....I found out more like the fpr was a turbo model, not an NA, base timing was off 5*, and other small things. I need to do a fuel pump before more testing can be done, and i want to build a little larger intake tube over the one I had. Ive done so much testing with different tps numbers, I have kinda forgotten what is what. So I found a guy parting out his 87 NA MT supra and bought the fpr, ecu and matching tps. The number is gone so I am not sure which one it is, but I do have a 28030, 14050, and a 20050. None make a difference at getting the WOT voltage on the IDL or the VTA wires.

Just curious if this will make a difference at all, or if just driving it, and as long as there is no code for a tps Im fine?

Ill be welding in a wideband sensor bung and tuning the afm via that, and to have a better idea of whats goin on.

Im so used to hooking up a laptop to my cars. I have a 501whp Volvo 940 with a stroked 2.5l 16v motor that I adapted Eclipse enging managment onto and running DSMLink (ECMLink V3) on speed density.

Nathaninwa · 06-18-2011, 06:29 PM

I have done some more google searching for IDL voltages. Reading on several forums, 3.5 volts is common on the VTA for wot throttle for all engine, and the IDL voltage at wot being 10-14 volts might be a misprint in the books brought over some of the earlier efi systems. Its supposed to be 5 volts at wot, but I dont get that either.

Ill check today with the 4 tps's I have. I know all sweep from .0x voltage at idle to about 3.5 when adjusted on the TB on the VTA wire, but can reach 4 volts when the sensor is spun by hand......Ill check for IDL voltages, what they are at idle, make sure it gos to zero, then should read 5 volts or so at wot?

I wonder if a problem could be I dont have the NSW hooked up to the ecu? Looking at teh schematic, looks like I want to supply 12 volts positive at idle, or any point the clutch is not depressed?

Nathaninwa · 06-18-2011, 10:52 PM

Just searched out that the nsw is 12pos only when the clutch pedal is depressed. So I'm chasing at this point if I really need 5 volts to the ecu on the idl pin at wot.

87hilux7mge · 06-18-2011, 11:21 PM

i would offer an opinion...but thou art far more versed with this situation than i am! when it comes to wiring, i cant tell a wire color from my...well you get the point.

personally re-wiring for ecus always scared the hell outa me, and something always ended up not working.

but props too you for doing what youve done!

Sonyps307 · 06-19-2011, 01:30 AM

I was having the same proble with the wot. I would get 3 volts at like little less then 3/4 throttle and then 0 at wot. Then I found out that I was calibrating it wrong the way tsrm shows is to test it. Read this link and do it his way should help.

http://mkiiisupra.net/bbs/showthread.php?t=12132

06-18-2011, 03:06 AM	#1
Nathaninwa Intake Join Date: Jun 2011 Location: Aberdeen, WA Posts: 43	TPS adjustments, unclear on voltage readings. Long story short....new registered member, but not at all new to the Supra/7m series engine scene. There is so much info that searching can usually find what I need. About 3 years ago I installed a 7m into my trail truck with a Cressida harness and ECU. Got it running and more or less drove it, but has always felt like its been down on power. So recently I have installed an 87 MT supra ECU, made an adapter harness from the old style plug to the newer style grey plug by sacraficing a spare ecu I had. Now I am going through and verifying all the info i can. Ive come down to the TPS....NSW/AC....and the speed signal My questions.....does the ECU need to have a NSW signal and an A/C signal, or will this just pop a code 51? Does the ECU use the speed sensor signal for any fueling/timing adjustments? And I have adjusted the TPS according the to the online TSRM ( http://www.cygnusx1.net/Supra/Librar...spx?S=FI&P=101 ), and all is within ohm spec at all points. But when it comes to checking voltages I have a problem. My information comes from ALLDATA. 87 supra 7mge should read 4-5 volts at wot on VTA, and I get 3.6 volts, no matter what tps number I am using. And I am supposed to get 10-14 on the IDL pin at WOT and I get zero. In reference, the 1990 Cressida ecu wants 3.2-4.2 at the VTA, and 4-6 volts on the IDL pin. I can adjust the tps to read 4.1 volts at WOT before the voltage drops out to zero, but then idle is way off....and neither option gives me 10-14 volts on the IDL pin. I have not tested the Cressida ECU, only the Supra as I am wantring to get away from the auto ecu setup, and possible power downage from improper inputs on the tranny side, and possible no VSS signal. Im working some other kinks on the truck before I can drive it, just wanting to solve the voltage questions on the ECU before I button it all up.

06-18-2011, 11:21 PM	#5
87hilux7mge walbro fp Join Date: Dec 2010 Location: spokane Posts: 479	i would offer an opinion...but thou art far more versed with this situation than i am! when it comes to wiring, i cant tell a wire color from my...well you get the point. personally re-wiring for ecus always scared the hell outa me, and something always ended up not working. but props too you for doing what youve done! __________________ 87 toyota 4x4 single cab short box pickup, 7MGZE.

06-18-2011, 03:41 PM	#2
Nathaninwa Intake Join Date: Jun 2011 Location: Aberdeen, WA Posts: 43	I should say that the truck does run....had a 51 code when I first started it, then when I was tweekin I was checking the VF voltages and tracking the afr with a narrow band guage....I found out more like the fpr was a turbo model, not an NA, base timing was off 5*, and other small things. I need to do a fuel pump before more testing can be done, and i want to build a little larger intake tube over the one I had. Ive done so much testing with different tps numbers, I have kinda forgotten what is what. So I found a guy parting out his 87 NA MT supra and bought the fpr, ecu and matching tps. The number is gone so I am not sure which one it is, but I do have a 28030, 14050, and a 20050. None make a difference at getting the WOT voltage on the IDL or the VTA wires. Just curious if this will make a difference at all, or if just driving it, and as long as there is no code for a tps Im fine? Ill be welding in a wideband sensor bung and tuning the afm via that, and to have a better idea of whats goin on. Im so used to hooking up a laptop to my cars. I have a 501whp Volvo 940 with a stroked 2.5l 16v motor that I adapted Eclipse enging managment onto and running DSMLink (ECMLink V3) on speed density.

06-18-2011, 06:29 PM	#3
Nathaninwa Intake Join Date: Jun 2011 Location: Aberdeen, WA Posts: 43	I have done some more google searching for IDL voltages. Reading on several forums, 3.5 volts is common on the VTA for wot throttle for all engine, and the IDL voltage at wot being 10-14 volts might be a misprint in the books brought over some of the earlier efi systems. Its supposed to be 5 volts at wot, but I dont get that either. Ill check today with the 4 tps's I have. I know all sweep from .0x voltage at idle to about 3.5 when adjusted on the TB on the VTA wire, but can reach 4 volts when the sensor is spun by hand......Ill check for IDL voltages, what they are at idle, make sure it gos to zero, then should read 5 volts or so at wot? I wonder if a problem could be I dont have the NSW hooked up to the ecu? Looking at teh schematic, looks like I want to supply 12 volts positive at idle, or any point the clutch is not depressed?

06-18-2011, 10:52 PM	#4
Nathaninwa Intake Join Date: Jun 2011 Location: Aberdeen, WA Posts: 43	Just searched out that the nsw is 12pos only when the clutch pedal is depressed. So I'm chasing at this point if I really need 5 volts to the ecu on the idl pin at wot.

06-19-2011, 01:30 AM	#6
Sonyps307 Lexus & 550's Join Date: May 2010 Location: Baltimore Posts: 526	I was having the same proble with the wot. I would get 3 volts at like little less then 3/4 throttle and then 0 at wot. Then I found out that I was calibrating it wrong the way tsrm shows is to test it. Read this link and do it his way should help. http://mkiiisupra.net/bbs/showthread.php?t=12132