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No Tps Voltage From Ecu

R34GTFOUR

By R34GTFOUR,
in Engines & Forced Induction

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R34GTFOUR Mentor

R34GTFOUR

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haha you need abit of humour when your day is going like shit...

anyway im guessing the z32 afm is shagged aswell, is there any resistance test or anthing to test the actual afm?

so another update:

I have a spare q45 afm, which i thought i would try. I hooked it up and the afm volts started to read as they should around the .2-.4volts when the engine was off but in the igntion postion. It was around 1v at idle, although it ran very rough (i had it on the vh41 setting for airflow)

I then stuck the stock r33 airflow meter and took it for a drive. The volt reading was simular to the q45, and the car reved as it should and there was no spultering or anything like that throughout the rev range. But it hunts at idle now... 700-1400rpm just goes up down up down.

So i now am concerned about 2 things,

1. why is it hunting?

2. why didnt it like my q45 afm even though i had it on the right afm setting?

I'll try and get some pics of it, the owner has done a decent job at making it look good, now it just needs to go properly haha

thanks again

Edited by R34GTFOUR
R34GTFOUR Mentor

R34GTFOUR

Posted
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Posted (edited)

as for the hunting side of things, i have reset the powerfc and gave it 30mins to "relearn" its idle, but it didnt work

I kinda knew it wont stop hunting the second i started it up with the reset ecu, it hunted straight away. When we first put a powerfc in my bros car, it never hunted at idle, it just ran really rich until it learnt the idle then it was all good.

BUT... (and there is always a but haha)

if i took timing out from the powerfc (about7-8degrees so its at about 8degrees BTC) then it stops hunting and idles at 950 but its not a normal idle. It kinda sounds liek its struggling even though the rpm doesnt change. If i return the timing to 15 BTC it starts hunting again.

so yeah... still thinking...

Edited by R34GTFOUR
paulr33 Grand Master

paulr33

Posted
Posted

check the physical loom connector to the PFC

as you have been messing around with wires and swapping ECUs check the actual plug is connecting properly

most common causes of crap running with the PFC and wierd idle etc is the actual harness isnt connected or is a bit loose

tighten the bolt a little too to make sure its straight and even and a firm snug fit. you should do the self idle learn, once the ECU is stable

it sounds like the stock AFM and q45 AFM you have are both OK its just you have some wierd idle problem - see above

R34GTFOUR Mentor

R34GTFOUR

Posted
  • Author
Posted
check the physical loom connector to the PFC

as you have been messing around with wires and swapping ECUs check the actual plug is connecting properly

most common causes of crap running with the PFC and wierd idle etc is the actual harness isnt connected or is a bit loose

tighten the bolt a little too to make sure its straight and even and a firm snug fit. you should do the self idle learn, once the ECU is stable

it sounds like the stock AFM and q45 AFM you have are both OK its just you have some wierd idle problem - see above

yeah i'll have a closer look at that tomorrow, although the plug looks fine and i always tighten the bolt to secure it all the way (i even press the outside edges of the plug cause the plug doesnt always go in evenly).

The actual harness itself hasnt really been molested too much, 99% of its be untouched. The only thing thats been "tapped" into is the main power (3pinouts), eccs relay was made up, water temp and tacho feeds to the dash, and the starter signal from the igntion barrel, and all these things check out as good.

I'm starting to feel sorry for the owner cause everything that shouldnt go wrong, has. I mean the odds that his q45 tps, z32 afm and a brand new power ALL being broken are almost statistically impossible but they are haha, i was intitially expecting one thing to be wrong lol

Everything besides the stable idle is working fine. The car revs fine, and powers beautifully right to limiter, no surging and spluttering, it just hunts.

Anyway i'm given up for the night, its only got a front pipe as an exhaust so its bloody loud and i dont want to get noise complaints, i'll wake them up first thing in the morning with it haha.

So tomorrow:

-Im taking my bros powerfc (the owners original powerfc is broken) out and putting it back in his skiz to make sure everything still works as it should (even though i just deleted his tune lol)

-I'm going to let the skiz run then record all the sensor signal voltages, then put the powerfc back into the hq ute and compare the signals, hopefully something jumps out at me.

-If not, im going to go pinout to pinout and record each and every value and compare that to the workshop manual and see what it says.

-If still no joy, i will purchase some fuel and some matches and burn the bastard down to the ground....

once again thanks, your input has helped me alot :D

R34GTFOUR Mentor

R34GTFOUR

Posted
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Posted (edited)

PROBLEM SOLVED :/

Okay so there was 4 main areas from stopping the rb25 from running properly:

1.

The powerfc was faulty, it didnt give out a tps voltage, I stuck my bros powerfc in it and it works fine. Hopefully he can get his fixed under warrenty

2.

He wired in the z32 afm plug so i just doubled checked the wiring. He was using a diagram that listed the wiring code as 1,2,3,4,5 (5wire plug), going from left to right, but the actual plug has the numbers 1-5 but 1 starts on the far right hand side. What this means is that he wired the signal and voltage back to front (SATO GTS, you were spot on haha). I re-wired it and it works fine now :D

3.

The tps that he had on the q45 wasnt actually a tps, but a throttle switch. The switch was either on or off, there was no variable to it. I stuck my q45 tps, which was the proper tps and problem solved.

4.

Now this last problem got me stumped for a while, and this is what was causing the hunting at idle. On the q45 throttle body it has its own idle up. It uses a coolant line going though it to warm up this valve, and once it hits operating temperature it pushes the throttle back to fully closed. Since we arent running any coolant to it, the throttle was open too much at idle so it was getting to much air and confusing the ecu making it hunt.

I pulled the whole assembly off the throttle body and adjusted the idle screw and it now sits dead on 800rpm, no hunting.

So after a LONG weekend, a car that barely started and hardly ran now starts first go, idles smoothly, and if the diff ratio wasnt so tall would be pretty quick, but it still revs freely and cleanly. Its going to get tuned and the boost upto 12psi and it should go alright for a hq ute.

Thanks again for everyone that replied, especially paul, it helped me alot.

Cheers :(

Edited by R34GTFOUR

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