Jump to content
SAU Community

Neo Fuel Problem

JonnoHR31

By JonnoHR31,
in Engines & Forced Induction

 Share

Recommended Posts

JonnoHR31 Grand Master

JonnoHR31

Posted
Posted

Just finished putting an auto er34 rb25det into a manual hr31, wired it up and got it running yesterday. It started straight away and idles like a dream, except the ecu isn't putting in any extra fuel when pumping the throttle, making it UN-drivable.

I've been over the TPS wiring several times, its got power and at the ECU plug the signal wire reads .45v when closed and 4.0-4.1v at WOT so the ECU is getting the TPS signal and it's working as it should. As far as i know the TPS signal is the only thing the ECU uses for throttle pump injection so this has me stumped. Does anyone have any ideas why this wouldn't be working and how to fix it? Possibly something I've missed in the wiring? Or is there something else than can cause the same symptoms (stabbing the throttle causes revs to drop until the ECU picks up the extra flow via the AFM) that I'm missing?

Link to comment
https://www.sau.com.au/forums/topic/406040-neo-fuel-problem/
Share on other sites
GTSBoy Grand Master

GTSBoy

Posted
Posted

You need to get a consult connection going so you can see what's going on.

You're also going to need to Nistune it if you want to be able to get around the lack of traction control and ABS that the ECU expects to see. Otherwise it will throw codes about the TCS/ABS comms and the TCS throttle position sensor.

JonnoHR31 Grand Master

JonnoHR31

Posted
  • Author
Posted

Consult isn't really possible at the moment unless I can find someone local with one, might have a scope around the WA section.

There was always going to be error codes but I was under the impression they wouldn't affect the actual running of the motor? I've taken it for a test drive and apart from this throttle hesitation it drives perfectly and doesn't have any cuts under full boost or anything.

GTSBoy Grand Master

GTSBoy

Posted
Posted

Is it all still connected? If the ECU can't see the TCS TPS it'll have a fit.

The ECU still chucks a wobbly even if it is connected - if there is no TCS computer present to make the throttle do the close-open dance when the ignition is switched on. That's one of the error codes that comes up. Nistune can mask it.

And this stuff can still cause hassles even if you get past all these little annoyances. The Nistune blokes worked out that if you do not have the TCS stuff working, when you up the boost/flow and get up to a reasonably high power level, then the ECU starts pulling shenanigans that feels like a rev/boost limit, and can't be tuned out. It is possible that Stagea ECU images do not have that problem (as they do not use TCS).

GTSBoy Grand Master

GTSBoy

Posted
Posted

Got it sorted, had the ECU boost sensor hooked up to the manifold, moved it to the intake and now it's running fine. Weird.....

That'll do it. I just checked my engine. That sensor is connected to the crossover pipe immediately adjacent to the BOV. I guess it is not supposed to see vacuum.

Hanaldo Grand Master

Hanaldo

Posted
Posted

The ECU still chucks a wobbly even if it is connected - if there is no TCS computer present to make the throttle do the close-open dance when the ignition is switched on. That's one of the error codes that comes up. Nistune can mask it.

And this stuff can still cause hassles even if you get past all these little annoyances. The Nistune blokes worked out that if you do not have the TCS stuff working, when you up the boost/flow and get up to a reasonably high power level, then the ECU starts pulling shenanigans that feels like a rev/boost limit, and can't be tuned out. It is possible that Stagea ECU images do not have that problem (as they do not use TCS).

Spot on. It's very annoying :glare:

DVS JEZ Grand Master

DVS JEZ

Posted
Posted

One of the wires was broken but it didn't make any difference.

Got it sorted, had the ECU boost sensor hooked up to the manifold, moved it to the intake and now it's running fine. Weird.....

Can u Please explain this a little more?

Had a 34 come in that had the same symptoms as urs after another mechanic did a headgasket. I had to disconnect the boost sensor to stop it trying to stall on takeoff. Such a simple little thing

JonnoHR31 Grand Master

JonnoHR31

Posted
  • Author
Posted

It seams to not like seeing vacuum, so just make sure it's hooked up somewhere before the T/B and it should be fine.

Thanks for the suggestions everyone.

Hi Jonno, i know its off topic but why did you get rid of your RB30DET and put a AUTO RB25DET neo into your HR31?

Sold the car to my younger brother, put a stocker neo (it's now manual) in for him and I'm selling my engine seperately along with a lot of other stuff.

StevenCJR31 Veteran

StevenCJR31

Posted
Posted

It seams to not like seeing vacuum, so just make sure it's hooked up somewhere before the T/B and it should be fine.

Thanks for the suggestions everyone.

Sold the car to my younger brother, put a stocker neo (it's now manual) in for him and I'm selling my engine seperately along with a lot of other stuff.

ah cool . . . are you using the auto ECU that you got with the motor? could be causing issues if you are?

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • Duncan
      spot the stagea

      By Duncan · Posted

      roof rail delete used to be a thing, they were made locally for a while too
    • AnimalGarage
      spot the stagea

      By AnimalGarage · Posted

      I can get more photos of it here soon and I plan to make a thread detailing the process. I received the car this way and it sorely needs refinishing. That is probably the most appealing photo of it. Up close it is fading, cracked, and needs to be re-glued. Depending on their condition I'm on the fence between refinishing or making a new set.  Another angle hiding the pimples and razor pumps  
    • AnimalGarage
      Can you mount the ATTESA pump in other locations?

      By AnimalGarage · Posted

      According to this thread the RS4V with build plate RC40 comes with the R200 diff @ 4.083 ratio as well (mine has said RC40 denotation). We may need to check if the axle stubs are the same pattern as well. The auto subframes have longer axles. However I think yours being a later Series 2 as well, we should have the same bolt pattern for the diff stubs. Unless your upgraded rear also has upgraded axles. Either way, I would not be opposed to pulling the covers to check so I can inspect that  fancy rear core  Also I don't have HICAS. I don't believe that should change things but I hope the people here with heaps more experience than me can correct me if I'm wrong   Let me know if you want to attempt to make this work and I can get some pictures of mine from under the car. 
    • joshuaho96
      R34 25GT Engine Light 21

      By joshuaho96 · Posted

      It's not that straightforward. For example I have had this code because my ignitor/power transistor wires were unplugged. It knows something is wrong but has no idea what it means. If you want to actually diagnose this I recommend following the service manual flowchart for code 21. Ohm out the harness, coilpacks, inspect the ECU, etc. And again, it's entirely possible for there to be no problem at all but if you're running a different coilpack it'll trigger the code because it doesn't like what it sees.
    • GTSBoy
      R34 25GT Engine Light 21

      By GTSBoy · Posted

      If it (the code) wasn't still current, it should have gone away by itself by now. No, nothing it 10/10. But it is quite likely. Everything else to do with the ignition could still be responsible (which is wires and connectors). The car is an old piece of shit now, so all the wires and connectors are also old pieces of shit.
×
×
  • Create New...