No Tps Voltage From Ecu

[R34GTFOUR]

Hey all,

Just trying to brainstorm some ideas, for a mate of a mate of a mate. Quick background, its a series 2 gtst motor thats been put into a hq ute, should be a lot of fun once its done. The car is about 3hrs drive away, and i havent seen its since he put the motor in and hes being ringin me every second day with problems, mainly electrical and its come to the point where he is going to tow the car up to my place so i can check it out, which im not really looking foward to. The car is running a powerfc (brand new), and the harness was modifed to suit the hq by a mob over east who apparently has done this conversion before, but some of the things they have done to the harness that hes told me about doesnt fill me with confidence. Anyhoo the car is also running a z32 afm and q45 throttle body. He has told me he has selected z32 under the afm menu on the powerfc so that should be fine.

Now to the problem at hand. He's telling me that he getting no postive and signal voltages from the throttle body, and the car is running like shit and wont rev over 2 grand. I told him to measure the voltage straight out of the ecu pinout to cancel any chance of the harness being the culprit, still no voltage, which concerns me cause i dont know of any reasons why the ecu wont put out a voltage to the throttle body, on either tps pinouts (postive, signal). He tries swapping out the powerfc with the stock ecu, and still no voltage sent out to the tps. So i was just wondering what you guys think might stop an ecu from sending out the tps voltage?? Hopefully the harness isnt screwed and fried the ecu, because now the car wont even start at all. It cranks and cranks but nothing. Its giving injector pulses to the injectors so thats all good, and its got spark (which he tells me looks a tad weak, but should be enought to start) so its got me stumped.

I suppose ill find out in a couple of weeks whats going on when he brings it up here, its always hard describing problems over the phone, then over the net haha.

cheers for any help

heres some pics of the ute i was working on

Edited March 10, 2008 by R34GTFOUR

[R34GTFOUR]

Ok the bloke just dropped the car off to me this afternoon and im chasing some opinons.

I have check each pinout of the harness from the ecu end to the the sensor plugs themselves and everthing matches up, no breaks in the wire. The ecu is getting all the power it needs (all pinouts measured), and is getting its earth.

Now, this is were it gets really weird. On the stock ecu the car will start and run, but since the z32 afm isnt tuned for it it wont rev over 2k rpm, but thats fine. There is tps power (5volts) and signal (.5V on close) and earth.

With the powerfc pluged in, it will barely start, and if it does, it dies shortly after. The afm has been changed in the menu so thats fine but the tps voltage magically disappears (hence it running like crap). No constant 5V, no signal, but this only occurs on the powerfc. On the hand controller it comes up highlighted that its a problem in the sensor section and reads 0V.

So to all the powerfc wizzes out there, why will the stock ecu send out a tps power but the powerfc wont. Nothing else changes, just the ecu.

Any help would be appricated.

[Adriano]

I dont know if i would do this, but you could bridge the 5v feed that goes to the AFM and run that to the tps, it could have an internal fault in the pfc, or try the pfc in an r33, maybe its a warranty claim.

[paulr33]

debug this with the std throttle body - you have changed too many things, new loom, different car, different t/b, different ECU and so on.

go and get the std throttle body - put it on and debug. once you clear the issue. then refit the q45 t/b. i bet the issue is with the t/b

using the stock ecu and q45 t/b as a debug point woudlnt provide useful results i would expect so dont bother

[R34GTFOUR]

cheers for the replies fellas.

unfortunately i cant use the stock throttle body cause he put on a greddy intake plenum and doesnt have a adaptor. Using a multimeter i've set the closed postion of the pts to .5V according to the workshop manual (of course this is only with the stock ecu, the powerfc doesnt do anything)

I've made a up a harness that will drop the battery power of 12volts to 5 volts so i'm going to try that and run a direct 5 volts to the throttle body and see if the powerfc likes it, i just hope by me running an external 5volts its not going to fry it.

With the airflow meter side of things, his stock one was broken in the halfcut, thats why he has a z32, but on the powerfc theres not fault codes for it and it looks ok.

My next step is getting a stock series 2 afm out of my bros car and wire it into his car, then just plug the standard ecu in and see if it runs (i think thats the only reason why it doesnt run smooth now, it would be fine with the tps, just not the z32 afm). If its all sweet if plug the powerfc in, and if it still acts like a piece of shit, then it has to be a faulty powerfc even though its brand new.

About 2months ago he sent up all his harness (he lives a while away) and i checked each pinout. He also sent up his powerfc and i put that in my bros car and it worked fine, so i assumed it was fine.

I was reading through the powerfc FAQ, and its says that there have been cases were the stock ecu will work but the powerfc wont, purely because of some engine control fuse(if its disconnected the stock ecu will work, not powerfc). Has anyone heard of this before?

Keep the posts coming with ideas

cheers

Edited March 8, 2008 by R34GTFOUR

[paulr33]

yeah there are some known issues where the PFC wont work but the stock ecu will when doing engine swap style changes - its in the FAQ

with the AFM and TPS connected up, turn the car to ON, but don't start it

on the hand controller goto ETC, SENSOR SW CHECK

AFM-1 should be like 1.0v or somewhere there - and it shouldnt move

TPS should be 0.33v or like 0.35v - and it shouldnt move - should move when you mash the accel pedal

if either of these arent reading like that, the car wont run/start correctly

[R34GTFOUR]

also the q45 throttle body is running a r33 gtst series 1 tps (series 2 are different and dont fit....)

ALSO THIS IS IMPORTANT:

when you buy powerfc's, you have to tell them if its for a series 1 or 2. I understand that this is just setting you change over. Its definately a series 2 motor and powerfc, but the only r33 skylines i have access to atm are series 1. When i check this in a series 1, will i have to change anything?

thanks again

[R34GTFOUR]

yeah there are some known issues where the PFC wont work but the stock ecu will when doing engine swap style changes - its in the FAQ

with the AFM and TPS connected up, turn the car to ON, but don't start it

on the hand controller goto ETC, SENSOR SW CHECK

AFM-1 should be like 1.0v or somewhere there - and it shouldnt move

TPS should be 0.33v or like 0.35v - and it shouldnt move - should move when you mash the accel pedal

if either of these arent reading like that, the car wont run/start correctly

tps is 0v, the main power feed from the powerfc to the tps goes missing so thats why there is no signal aswell, yet a plug the stock ecu and i'll get a constant 5v feed and my idle postion is .5v. Its doing my head in...

On the powerfc, it highlights the tps, so its got a problem with it, even though the actual tps is off a r33 skyline

afm is reading 3volts with ignition on but not started, i cant get it running long enough on the powerfc to see anything.

[paulr33]

3v is too high for the AFM not running - unplug it and see if it starts and idles

theres no such thing as different model PFC to suit series 1 or 2 - its the same unit and theres no option to choose between s1 or s2

[R34GTFOUR]

3v is too high for the AFM not running - unplug it and see if it starts and idles

theres no such thing as different model PFC to suit series 1 or 2 - its the same unit and theres no option to choose between s1 or s2

sweet, thanks again for the quick replys, appricate it

I'll try that, but it still doesnt explain why the tps power wouldnt be there. I'm just ging to stick a stock afm so at least that "cancels" out and chance of that being a problem aswell.

With the z32 afm, do you definately use the vg30 selection under airflow? Its the option ontop of the VH45 (which i would assume is for a q45 afm)

[paulr33]

yeah with the Z32 you need to choose VG30 80mm from the menu

VH41 is for the Q45 AFM

these just alter the load ramp, the Z32 should actually run and start OK with even the stock AFM selected

[SATO GTS]

if you are getting 3volts at the air flow meter for the Z32 you may have your 12v and signal wire the wrong way round..

i know from experience . should not do any damage to the pfc if not connected for too long.

[R34GTFOUR]

ok just a quick update,

i've wired in the stock r33 afm, set the tps on the q45 throttle body to .4V on fully closed and connected the stock ecu and VRRROOOOM. The thing starts, idles, revs, it does what it should

Then the spanner is thrown into the works...

I connected the powerfc, I havent changed anything but the ecu, and now no tps voltage

Im going to test the powerfc on another skiz in the next hour or so, but im still scratching my head. I'm really keen to find out why its doing what it is doing.

If the powerfc turns out fine, then im just going to run a 5volt positive to the throttlebody on a external line.

any other ideas?

[R34GTFOUR]

I just tried starting it on the powerfc, seems to run fine, its revs freely but it just idles too high (and still shows no tps voltage)

also on a side note (and i doubt this will affect it, but who knows..)

The owner has installed a speco tacho, it will read fine on the power fc, but plug the stock ecu and it wont pick up at all. The feed has just been tapped into the harness where the tacho pinout is on the ecu so its the same for both ecu's. Its another weird thing...

[paulr33]

where there is no TPS signal the PFC goes into protect mode and kicks the idle rpm to 1500RPM

[R34GTFOUR]

where there is no TPS signal the PFC goes into protect mode and kicks the idle rpm to 1500RPM

i took the powerfc out and tested it on my bros skiz and it didnt give out a tps power, so the powerfc is buggered for some reason.

I got my bros powerfc and plugged it into the hq ute and guess what? its got tps power, so its definately the orginal powerfc thats got a problem, its not the car.

Anyway i started it up, still with the standard afm and it purred like kitten haha, so i though i would stick the z32 afm back on...

THEN...

The car idles rough as guts and the afm voltage is at 3volts, so its way off. I selected the correct setting for airflow meter setting on the powerfc, but it still reads 3volts. I checked, then re-check then double checked again the wiring going to the afm and its correct. So why would the afm give out a false reading?

Im going to try and clean it, but whats the chance of this guy having all these things wrong, and ALSO have a busted afm?

thanks

[paulr33]

if its reading 3v like that its toast or the ground is shagged - where is your ground coming from

[Guilt-Toy]

I know this sounds silly.. BUT i got stuck with it before.

check the power fc where it pluggs into the loom, sometimes it does not go in all the way on the edges and it can cause this problem. It has happened to me before.

If you can see a gap on the ends of the plugs where it plugs in then id undo it and re-connect it, its a good idea to screw the 10ml bolt in 2 turns and then press down on both sides and repeat untill its all the way down.

If this fix's your problem then good, if not then it would be a good idea to check this next time you have any issues anyway.

[PurpleR32]

where there is no TPS signal the PFC goes into protect mode and kicks the idle rpm to 1500RPM

Thats because you dint fill out your TPS report correctly

Sorry, I couldn't resist....I will leave now on the basis i have no helpful information to your problem

[paulr33]

haha