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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. |
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. |
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? |
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.
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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! |
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 |
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" |
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.
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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. ;) |
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. |
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... :frown:. 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. |
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. |
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.
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Just looked at my pinout, and I do have the VSV1 output which is an intake air control. Mmmm, maybe Ill Ebay an upper half of an NA setup.
What about the VSV2, which is a fuel pressure up valve? |
VSV2 modulates the FPR's vacuum signal. The Cressida had it too... Most vehicles have one and you definitely want that in place.
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OK, so I just picked up an NA intake.....still need to find one of them VSV valves, but I might be able to scour one up here at the house.
Im about out of money now for this project at the moment, got some dollars to put onto a T56 for my Volvo project. I should have enough parts to get it up and running far better than before. Maybe anyone got a couple of them VSV valves kickin around? |
Heh, I've got a bucket of misc VSV's somewhere (probably in storage as I haven't seen it in some time... that or someone snagged it). Any 12v, two position VSV will do though. Just hit up a junk yard and grab a few VSV's from Toyotas, Hondas, Mercedes (Mercedes has a couple which only cost about $30 new... sorry, don't have the part numbers handy); You'll be looking for one with three nipples (one is for the vacuum constant source, one is closed when there's no power but opens when there is power and the other it normally open and closes with power). Typically they'll have a vacuum line running to two nipples and a breather on the third. I don't have time to go hunting, but if I come across one which will work I'll let you know... Still probably going to be quicker for you to just hit a salvage yard and grab a few for $5.
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Cool, I am headed to the yard to test fit some stuff, so I head over to the Toyota section and check it out.
Thanks for the reply. |
After reading up on the ACIS system its really cool, and I think Ill benefit 100% from the lowedn torque when Im out wheelin....I like to motor through second gear in lowrange and grunt though the trails, I have always lacked wot pulls from like 1500/2000 when under load. Doing some more searching brought me to TB swaps....I see the stock is a 60mm for a 3.0. Volvo has a 2.8l inline 6 that uses a slick 65mm throttle. Im a fabricator by trade so working the shaft to install the toyota tps finger and making an adapter plate to fit the Toyota tps should be pretty easy. If not, the stock volvo tps is a potentiomter, wire that in and use a switch like a nitrous activater for the idl pin. I would just have to setup and see what the voltages range from using the Volvo tps. But I think I can mod the Toyota unit on there.
Im also looking at the Pacesetter 5m header....I think I have room between the frame and bellhousing to get it in there. http://i816.photobucket.com/albums/z...621_181547.jpg |
I seen a guy use a TB from a newer mustang one of the daul butterfly ones and modded the n/a Y piece to fit it.
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I think I saw that right up....throttle linkage would be tricky as off idle would be a bit touchy, and that much TB I think is to much, and could be that 3/4 throttle is acutally WOT since the motor cant really suck any more!
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Bigger throttle body on an N/A will most likely result in a more sluggish throttle response. Air velocity is higher the narrower the aperture but at a lower volume (You get the air in there faster and it's cooler). Air is charge is denser but also slower with a larger aperture... it's also in there sitting over the engine longer. Tune your intake for your needs. Physics my man, physics... and while we're on that subject, go ahead and put back the Helmholtz resonator that I'm sure you're also missing.
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I have never really looked into the resonator...I was told long ago that it quieted the stock intake piping down for quiet operation. Im actually running 3 inch IC piping over to the AFM in the fender/core support junction.
So on the subeject, what about the pace setter headers I see on Ebay, 3-1, 2-1 setup. My stock 5mge manifold is cracked (fits the frame rails better than the 7mge did) Im thnking I can get it to fit in there. |
Yes, it quiets things down a little... but that's not the entire (or arguably the primary) reason for it... I've posted exhaustively on this in the past, research it a bit... then put it back on. ;) To put it simply: It quiets things down by reducing turbulence. Put it on at about the same distance from the throttle body as it is in the stock location.
I hope that air filter isn't in the engine bay... (or a K&N filter... :barf: especially on an off-road vehicle) Barring significant machine work you're not going to get much more out of the 7M-GE than Toyota already managed to squeeze out of it in the Supra version. Even with it you won't see amazing results, I know people who've bored the engine to its limit, put in stroker kits and custom cams, over sized valves and still don't even see 300RWHP. The 7M is just a poor 'all-motor' platform. I wouldn't really go beyond a port and polish, properly tuned intake and exhaust for your build, as cool (ceramic coated intake plumbing and inlet OUTSIDE of the engine bay) and smooth of an intake charge as possible. Don't run higher octane fuel than you need. Run the right temp range spark plugs (hotter plugs are NOT just magically better). Stop me if you already know all of this... :P Adding a thermostatically controlled oil cooler is a VERY good idea. If you're willing to sacrifice your highway mileage (:rofl2:) a shorter end-gear would help a lot. Cams are a biggie naturally but keep an eye on the profile as the off-the-shelf aftermarkets are generally designed with the GTE in mind. There are no excellent exhausts for the GE out there. You may try the Pacesetter or OBX, they'll both benefit from better scavenging as long as the rest of your exhaust is properly tuned for it (see: the right size piping for the job). |
Well I need one, so I think Ill get that pacesetter header and give it a try. I got my 65mm throttle all done, well just need to weld on the fingers for the TPS, but it all fits up.
Ill tune the AFM with a wideband and dial it all in as well. Im expecting my NA intake anyday. Do I need to make a vacuum canister to operate it, or just plum it into the plenum itself? I can take some 3 inch intercooler piping and cap the ends and tap for some fittings if need be. Im reading on that Hemholtz resonator....sounds very interesting. http://i816.photobucket.com/albums/z...623_164440.jpg http://i816.photobucket.com/albums/z...623_164452.jpg http://i816.photobucket.com/albums/z...623_164524.jpg |
Bumping this thread since all the relevant info is here. Finally got all the oodd projects done and have spent the past week tiding up the supra manul ecu swap over the auto cressida. Have the n/a intake and the vsv valve all wired up. I got the speed signal from the dash wired over and am about an hours way worth of work to starting this thing back up.
My question is, the ecu has a pinout for the clutchswitch, and the brake switch. Are these necesary inputs for proper operation? Is there a function ill lose by not hooking them up? |
I did some research and found autoshop101.com to be very imformative. Neither is actually needed, but the clutch switch 0/12+ helps determine the proper idle speed based on other inputs and the brake switch modifes fuel cut rpm. Ill get these hooked up in a few weeks, but now I can tool around town knowing the ecu wont be thinking the wrong things.
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So got the truck fired up today. Pretty much like I shut it off yesterday, but its been 10 months and an intake/ecu wap later! Have my wideband installed and the thing ran really lean at idle. I played with the flapper door bypass screw and rotated the spring setting. At first it had a hard time idleing lean in the 17's for afr, had to loosen the door to get it to come down to low 15's at idle, but now the door is so loose the arm does not turn the fuel pump off anymore?
Seems weird since Im running an 87 ecu which is tuned around the 295cc injectors, and I have the later Cressida 315cc injectors. Base timing is at 10*, TPS is properly setup by grabbing the voltages at the ECU. Im going to get it out on the road tomorrow to see how it drives, and tune the afm more. Ill be checking the VF signal and keeping an eye on AFR's while cruising to try and target the 2.5 volt VF (zero fuel trim) and see what wot is as well. Im bothered by the idle tune at this point. Is there anyway I can wire in a heated O2 and have closed loop idle, or does the early (87 ecu) not go closed loop idle? One more question. How is the crankcase vent supposed to be routed on an NA setup. Mine is setup like the Turbo system, gos from the valve coves to the TB so full engine vacuum is on the case at all times. There is a restrictor inline in the system like stock too. There is so much vacuum in my case that I get seal squeel, at first it sounded like a throwout bearing going bad. So for the last couple years I have had a small hole drilled into the fill cap. I dont think this is enough to significally lean out the mixture, but it is unmetered air. |
Everything is good. i went ahead and vented the motor to atmosphere to rid of the vacuum leak. I swapped out AFM's and that solved the door closing problem. And was able to get it tuned off the wideband and the VF feedback. Took one tooth richer than the virgin afm was setup for. It idles at 15.5, cruised closed loop around 15.0 and under wide open throttle, it dips to a 12.5 to 12.3. Seems to have a bit better off idle tq than the Cressida setup too. Now just to drive it and see the mileage I get.
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The air bypass in the AFM isn't meant to be used as an idle adjustment... it adjusts the airflow across the whole scale. It's a bad idea to employ it for any type of fuel tuning. Get a real fuel controller or go stock... you're just going to melt something.
Just for my own edification.... Just how does opening something to atmosphere FIX a vacuum leak? :nuts: EVERY MKIII runs closed loop 90% of the time... '86.5, '87 and earlier are no exception. You can't use Vf to tune. P E R I O D. It serves as a rough guide at best. And you can't even use it a a rough guide for open loop operation. Heated O2 sensor? Sure, why not? Just use a relay triggered by the fuel pump relay and with it up for 12v. You can't just wire in a wideband O2 sensor though.... just narrowband. |
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I haven't the patience for everything in this build that I disagree with or that could be handled much more practically and provide greater reliability and response... Perhaps someone else will step in.
Vf is indicative of many things and there's actually a LOT more in that signal than just fuel trim feedback. Hook it up to an oscilloscope if you have one and check it out. It's also not a reliable indication of AFR as a narrowband isn't really capable of providing reliable information about your AFR. The narrowband is essentially disregarded in open loop operation and Vf represents changes made for other reasons... The only thing you know is that it's making changes that it 'thinks' need to be made; This could be because of detected knock, an OX signal that isn't within spec (for a narrowband signal that means it has to be at the correct frequency with relation to injector and spark timing and within 400mV and 500mV), or due to learned information from driving conditions four weeks ago or any other of three dozen reasons. Vf is unreliable except for situations where you're trying to get one of the more advanced piggyback EMS dialed in as close as possible so they'll live together in piece and it's still not what I'd call trustworthy. (I just re-read your response concerning tuning with Vf) I'd really not rely on it while the TCCS is in it's initial learning mode... it doesn't even know what it's going to do next yet in this state. In the stock location the narrowband should not cool at idle to such a degree as to skew readings notably. If it is cooling to that degree you may want to invest in insulating your header as that heat's probably ending up in the engine bay and the gasses in the exhaust piping are ending up cooler, denser and thus slower moving than is preferable. Adjusting the tension spring in the AFM causes a non-linear shift in the measurement of airflow. The vane bypass creates a linear shift, IIRC. In both cases you adjust the entire scale and can not just tweak idle or whatever. Closed loop operation helps as the ECU corrects the shift you've caused, but it's limited in response time, how much it can correct and so on. But again I recommend you do it right and get a fuel controller. You may also screw with your tip-in/out response as the plate is prone to bouncing now due to the unanticipated loss of tension (only really an issue if you make a significant adjustment). I'll grant that one or two teeth either way isn't going to create a significant shift but it isn't without possible side-effects. Opening the crank case to atmosphere allows more pressure to build within, water vapor and corrosive hydrocarbons to accumulate in your oil (reduced oil and bearing life), reduces the efficiency of your oil seals and piston rings, etc... Fair trade off just to HIDE another problem? FIX the real problem. Anyway, good luck with the project and have fun with it! |
Thanks for the reply Cre. With the one tooth adjustment on the wheel and a slight turn in on the idle bypass, everything is still in check. Truck runs great (except for a bad cold start injector) and I'm pleased with the responce and power, read that as low end tq, that this motor has now. I'm still unsure if I have an NA or turbo intake cam, so in a while ill pull the cover and measure lobes.
But for a truck that's 4500lbs, geared 4.88 with 36 inch bias ply tires and duel transfer cases, it go really good. Thanks for all the help. |
I'd love to try that short end gear in a MA61 with a 7M-GTE swap.... :bigthumb:
I'm glad it's all working well for you! EDIT: What's up with the CSI? |
I hope its just a bad unit. It looks crusty on the stem. I bought an NA intake off Ebay, so I know nothing about it. The cold start wiring works afaik since it would lite right off on the Cressida stuff. A friend has a V6 csi that Im going to swap out (plugs and hose the same, just have to woller the bolt pattern)
Truck takes like 15 seconds for it to fire up in the morning, but with a little heat, or even the time between lunch and works end, it will fire right up Seems to just be a cold soak. I do have a fuel pressure tester plumbed in, and in all cases, the pressure has bleed off, but builds instantly. If the V6 fails to give good results, i trim down the turbo csi, plug the end and drill some squirter holes on either side. That MA61 would be a hoot with a gear setup like that! |
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