TPS adjustments, unclear on voltage readings.

Nathaninwa · 06-19-2011, 07:12 AM

Thanks for the link....I had acutally read that before with all my searching. So today I cycled each of my TPS's quite a few times....must have done something because they all seem to work now.

When all are calibrated properly, Im seeing between .5 and .8 volts on the VTC wire at idle, and close to 3.6 volts at WOT with a smooth curve inbetween.

I also figured that Toyota is using the absence of voltage for its idle circuit. When ohmed out properly with feeler guages, I get near .5 volts at idle, and anything above that is 5 volt reference now. All my tps's read the same, regardless of part number. So I am getting my WOT throttle voltage, and hence why there is no voltage check at idle, only wot.

Ill do some more seaching, but I just need to figure out what the ECU uses the speed signal for. Its generated on the back of the cluster and gos to the cruise and engine ECU's. I have found one reference that it uses it for "some ecu functions"

Nathaninwa · 06-19-2011, 10:05 PM

More research on the VSS signal, shows that the ecu uses it for optimal timing and fueling based on rate of speed change....so it is important for me to find and hookup the signal.

cre · 06-20-2011, 03:12 AM

Vc should be between 4.8v and 5v.
VTA should range from .5v (as low as .4v is fine, IIRC) to 3.48v (higher than 3.48 may result in a fault code depending on the actual tolerance of the components in your specific ECU).
Vs should range from .4v to 4.8v.
IDL should be 0v with the throttle pretty much closed... otherwise it's an open circuit... should be around 5v, but it's irrelevant.

I presume that by Vss you're referring to Vs or the VAF signal input? Yes, Vs is used in most calculations as long as a valid signal is present... after an out of range signal is diagnosed by the ECU it will revert to a base map, but you won't like it.

Also, the ECU does need a signal from the stock oil pressure sensor (in case you don't have that connected either)..... god I hate these hack jobs... full swap or standalone any day please.

Did you also swap in the N/A Supra's intake plenum and get the ACIS system functioning?

BTW, what injectors are you running? There's no practical way to run the low impedance injectors used in the older 7Ms on the newer revision 7M ECUs; There's significant latency introduced and flow is erratic at best if you try simply wiring in load resistors. Now the other way around well, it works fine but I don't know why you'd ever want to (peak and hold injectors are far more readily available).

EDIT: And damn... if I had a nickel for every time All-Data was wrong about something.... well, I'd only have about a handful... but the point stands that I'd still have a handful.

Nathaninwa · 06-20-2011, 03:55 PM

Thankyou for the reply. In the beginning I was trying to have just a stock running engine, turn key, no problems. It has ran for 3 years this way, just down on power. I have thoughts of the DIY pnp megasquirt, but the cressida harness plug is not avaialble, however the earlier supra model with the yellow plugs is, so rather than spending a ton of cash on MS I thought I would start with the supra ecu since I needed to make an adapter harness anyways. So megasquirt is in my future, just toying with this route first.

I don't have the NA intake....the cressida was setup to run the GTE intake, and from what I have read, the 86/87 supras ran the GTE intake as well, so no wiring for that is avaialbe.

Ill look tonight, but I don't remember seeing an oil pressure input for my model year ecu.

I was refering to the vss, or the speed sensor....looks like that is an important ecu input.

All the readings ohms/volts specified are within spec on the afm and tps circuits now.

I should note, that tho I have not started it yet.....with the codes cleared in the ecu, I can work the throttle, and afm, recheck for codes and don't get any. I'm reworking my intake pipe and need to get the new fuel pump in...by the weekend I should be started back up.

And I'm runnning the later model high z na injectors.....they are wired into my early ecu without a resitor pack. So I have the 315cc green tops vs the 295cc low z yellow tops.

cre · 06-20-2011, 08:42 PM

The Crassida's intake is different than the GTE's... it just looks similar. The Supra and the Crown N/A's (ALL YEARS of 7M and also the 2JZ series) ran a very different setup than the Cressida's thanks to the ACIS system and tuning differences based on it.

Those flow numbers for the injectors aren't quite accurate. That's pretty much just a step above the middle of the VERY broad range that Toyota specifies for its injectors and rather hopeful for 20+yo injectors. The 89+ injectors are supposed to flow 276 to 340cc/min, pre89 aren't much less. Toyota also says a variance of as much as 36cc/min between injectors is fine...

. It's irrelevant to me as I won't install used injectors unless they've been cleaned and blue printed... half of the ones you send to the shop are trash at this age. I misread though and thought you meant you were running the newer ECU with the grey plugs, not that it was used to build a Fields harness.

The VSS is labeled SPD in Toyota's publications, you'll probably find more info looking for that. I think most of the Toyota speedometer heads from that vintage provide the same VSS signal.

The oil signal may only be used in the GTE ECU, I can't recall.

Nathaninwa · 06-20-2011, 09:13 PM

Do you think I would benefit from the GE style intake? I use the motor a lot in the lower rom range as the truck has 4.88 gears and duel transfer cases. Is the internal tuned flapper a mechanical system or something wired into the ecu?

That's crazy on the injector variances. I did have these cleaned on an injector cleaning bench but not flowed.

I did just buy a set of Fuel Injecotr Clinics 2150cc injectors for my Volvo. The spec sheet only shows a difference of 2cc flow, nor matched within a half percent! Lookin to get 600whp out of them.

Ill do some more research on the spd acronym.....either way its generated at the cluster so ill locate it and ship it over there to the ecu.

Thanks for all your guys help.

cre · 06-20-2011, 09:50 PM

The ACIS system helps most with the lower torque curve but it also helps ensure a more consistent flow to all of the cylinders. The system just consists of the upper intake plenum (surge tank) and the "Y" pipe, a vacuum canister, one VSV and different throttle body. I can't remember which VSV output it is on the ECU... I THINK it's just labeled VSV1 or VSV2 in the service manuals... can't look right now and I don't have a MKIII here to check for ya.

06-20-2011, 03:12 AM	#3
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Vc should be between 4.8v and 5v. VTA should range from .5v (as low as .4v is fine, IIRC) to 3.48v (higher than 3.48 may result in a fault code depending on the actual tolerance of the components in your specific ECU). Vs should range from .4v to 4.8v. IDL should be 0v with the throttle pretty much closed... otherwise it's an open circuit... should be around 5v, but it's irrelevant. I presume that by Vss you're referring to Vs or the VAF signal input? Yes, Vs is used in most calculations as long as a valid signal is present... after an out of range signal is diagnosed by the ECU it will revert to a base map, but you won't like it. Also, the ECU does need a signal from the stock oil pressure sensor (in case you don't have that connected either)..... god I hate these hack jobs... full swap or standalone any day please. Did you also swap in the N/A Supra's intake plenum and get the ACIS system functioning? BTW, what injectors are you running? There's no practical way to run the low impedance injectors used in the older 7Ms on the newer revision 7M ECUs; There's significant latency introduced and flow is erratic at best if you try simply wiring in load resistors. Now the other way around well, it works fine but I don't know why you'd ever want to (peak and hold injectors are far more readily available). EDIT: And damn... if I had a nickel for every time All-Data was wrong about something.... well, I'd only have about a handful... but the point stands that I'd still have a handful. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar ---> Last edited by cre; 06-20-2011 at 03:14 AM.

06-20-2011, 03:55 PM	#4
Nathaninwa Intake Join Date: Jun 2011 Location: Aberdeen, WA Posts: 43	Thankyou for the reply. In the beginning I was trying to have just a stock running engine, turn key, no problems. It has ran for 3 years this way, just down on power. I have thoughts of the DIY pnp megasquirt, but the cressida harness plug is not avaialble, however the earlier supra model with the yellow plugs is, so rather than spending a ton of cash on MS I thought I would start with the supra ecu since I needed to make an adapter harness anyways. So megasquirt is in my future, just toying with this route first. I don't have the NA intake....the cressida was setup to run the GTE intake, and from what I have read, the 86/87 supras ran the GTE intake as well, so no wiring for that is avaialbe. Ill look tonight, but I don't remember seeing an oil pressure input for my model year ecu. I was refering to the vss, or the speed sensor....looks like that is an important ecu input. All the readings ohms/volts specified are within spec on the afm and tps circuits now. I should note, that tho I have not started it yet.....with the codes cleared in the ecu, I can work the throttle, and afm, recheck for codes and don't get any. I'm reworking my intake pipe and need to get the new fuel pump in...by the weekend I should be started back up. And I'm runnning the later model high z na injectors.....they are wired into my early ecu without a resitor pack. So I have the 315cc green tops vs the 295cc low z yellow tops. Last edited by Nathaninwa; 06-20-2011 at 03:59 PM.

06-20-2011, 08:42 PM	#5
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	The Crassida's intake is different than the GTE's... it just looks similar. The Supra and the Crown N/A's (ALL YEARS of 7M and also the 2JZ series) ran a very different setup than the Cressida's thanks to the ACIS system and tuning differences based on it. Those flow numbers for the injectors aren't quite accurate. That's pretty much just a step above the middle of the VERY broad range that Toyota specifies for its injectors and rather hopeful for 20+yo injectors. The 89+ injectors are supposed to flow 276 to 340cc/min, pre89 aren't much less. Toyota also says a variance of as much as 36cc/min between injectors is fine... . It's irrelevant to me as I won't install used injectors unless they've been cleaned and blue printed... half of the ones you send to the shop are trash at this age. I misread though and thought you meant you were running the newer ECU with the grey plugs, not that it was used to build a Fields harness. The VSS is labeled SPD in Toyota's publications, you'll probably find more info looking for that. I think most of the Toyota speedometer heads from that vintage provide the same VSS signal. The oil signal may only be used in the GTE ECU, I can't recall. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

06-20-2011, 09:50 PM	#7
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	The ACIS system helps most with the lower torque curve but it also helps ensure a more consistent flow to all of the cylinders. The system just consists of the upper intake plenum (surge tank) and the "Y" pipe, a vacuum canister, one VSV and different throttle body. I can't remember which VSV output it is on the ECU... I THINK it's just labeled VSV1 or VSV2 in the service manuals... can't look right now and I don't have a MKIII here to check for ya. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

06-19-2011, 07:12 AM	#1
Nathaninwa Intake Join Date: Jun 2011 Location: Aberdeen, WA Posts: 43	Thanks for the link....I had acutally read that before with all my searching. So today I cycled each of my TPS's quite a few times....must have done something because they all seem to work now. When all are calibrated properly, Im seeing between .5 and .8 volts on the VTC wire at idle, and close to 3.6 volts at WOT with a smooth curve inbetween. I also figured that Toyota is using the absence of voltage for its idle circuit. When ohmed out properly with feeler guages, I get near .5 volts at idle, and anything above that is 5 volt reference now. All my tps's read the same, regardless of part number. So I am getting my WOT throttle voltage, and hence why there is no voltage check at idle, only wot. Ill do some more seaching, but I just need to figure out what the ECU uses the speed signal for. Its generated on the back of the cluster and gos to the cruise and engine ECU's. I have found one reference that it uses it for "some ecu functions"

06-19-2011, 10:05 PM	#2
Nathaninwa Intake Join Date: Jun 2011 Location: Aberdeen, WA Posts: 43	More research on the VSS signal, shows that the ecu uses it for optimal timing and fueling based on rate of speed change....so it is important for me to find and hookup the signal.

06-20-2011, 09:13 PM	#6
Nathaninwa Intake Join Date: Jun 2011 Location: Aberdeen, WA Posts: 43	Do you think I would benefit from the GE style intake? I use the motor a lot in the lower rom range as the truck has 4.88 gears and duel transfer cases. Is the internal tuned flapper a mechanical system or something wired into the ecu? That's crazy on the injector variances. I did have these cleaned on an injector cleaning bench but not flowed. I did just buy a set of Fuel Injecotr Clinics 2150cc injectors for my Volvo. The spec sheet only shows a difference of 2cc flow, nor matched within a half percent! Lookin to get 600whp out of them. Ill do some more research on the spd acronym.....either way its generated at the cluster so ill locate it and ship it over there to the ecu. Thanks for all your guys help.