Jump to content
SAU Community

Rb20det Idle Problems?!?!?!?!?!

BlueRB240

By BlueRB240,
in Engines & Forced Induction

 Share

Recommended Posts

BlueRB240 Collaborator

BlueRB240

Posted
Posted

Ok here is the problem, I can't seem to get my car to idle unless I pull the big vacuum line off that goes to the break booster. If I leave it on and try to start the car it just won't turn over. The air fuel ratio while it's cranking with no vacuum leak is like 10ish, with it off it's around 14ish and when it fires up it's at 16ish. So when I fire it up with the vacuum leak that car will ilde high but it will stay running until I seal up the leak then the airfuel ratio shoots to the 10's and the car stalls out. I tried to unplug the maf to get it to idle and it just won't do it. Checked the ecu for codes but none all is good. I thought maybe my injectors were dirty and they were a little from the report I got back after I had them cleaned and balanced. I'm running 824cc Sard injectors with a Nistune Ecu and Denso 280lph fuel pump. I also reprogrammed my nistune and tried it another Rb20 and that car fired up like normal. I'm at a very big loss because I have never seen this before.

Link to comment
https://www.sau.com.au/forums/topic/294968-rb20det-idle-problems/
Share on other sites
payback21 Community Regular

payback21

Posted
Posted

Mate i had this exact same problem with my wifes car recently and it took me a few days to nut it out.

After changing ecu, plugs, coilpacks, afm, fuel pump, checked electrical and intercooler plumbing but nup nothing. But after the few days of swearing and cursing i found it.

It ended up being the intake pipe that goes from the AFM to the turbo. It had wriggled off the front of the turbo and was just sitting in front of it. I couldnt bloody tell because as most know, the intercooler piping covers alot of the turbo so you cant visualy see it unless you look for it.

With the intake wriggling off the front of the turbo, it was sucking air in which was stuffing the fuel mixture ratio hence the reason why it wouldnt idle and it couldnt make boost.

Put it back on and now shes all sweat. I would also check the plumb back system if you have it as it may be sucking air from there somewere too.

Im not sure if this is going to solve your problem but check it out. Anything is possible. Hope you have some luck. Its a very annoying problem to find.

BlueRB240 Collaborator

BlueRB240

Posted
  • Author
Posted
Mate i had this exact same problem with my wifes car recently and it took me a few days to nut it out.

After changing ecu, plugs, coilpacks, afm, fuel pump, checked electrical and intercooler plumbing but nup nothing. But after the few days of swearing and cursing i found it.

It ended up being the intake pipe that goes from the AFM to the turbo. It had wriggled off the front of the turbo and was just sitting in front of it. I couldnt bloody tell because as most know, the intercooler piping covers alot of the turbo so you cant visualy see it unless you look for it.

With the intake wriggling off the front of the turbo, it was sucking air in which was stuffing the fuel mixture ratio hence the reason why it wouldnt idle and it couldnt make boost.

Put it back on and now shes all sweat. I would also check the plumb back system if you have it as it may be sucking air from there somewere too.

Im not sure if this is going to solve your problem but check it out. Anything is possible. Hope you have some luck. Its a very annoying problem to find.

I'm running a blow through setup on my car. P1010630.jpg

P1010737-1.jpg

I did have to take my Rips manifold off to change my thermostat and thats when this all started to happen. I took it off again and didn't see anything and installed a new gasket. I'm going to start it again tomorrow and spay some brake cleaner around the flange to see if the idle changes might be a leak or something.

blind_elk Grand Master

blind_elk

Posted
Posted

What fuel pressure are you running?

Considering that you are running injectors probably 4x standard flow rate, I'm surprised it runs at all. You have a programmable ECU - trim some fuel out of it at 'start' and 'idle'.

BlueRB240 Collaborator

BlueRB240

Posted
  • Author
Posted
What fuel pressure are you running?

Considering that you are running injectors probably 4x standard flow rate, I'm surprised it runs at all. You have a programmable ECU - trim some fuel out of it at 'start' and 'idle'.

I have it set to 40psi without the vacuum line. Nistune realtime board for adjustment.

  • 2 months later...

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

    • dbm7
      R34 Skyline climate control unit transistor

      By dbm7 · Posted

      Bit of a pity we don't have good images of the back/front of the PCB ~ that said, I found a YT vid of a teardown to replace dicky clock switches, and got enough of a glimpse to realize this PCB is the front-end to a connected to what I'll call PCBA, and as such this is all digital on this PCB..ergo, battery voltage probably doesn't make an appearance here ; that is, I'd expect them to do something on PCBA wrt power conditioning for the adjustment/display/switch PCB.... ....given what's transpired..ie; some permutation of 12vdc on a 5vdc with or without correct polarity...would explain why the zener said "no" and exploded. The transistor Q5 (M33) is likely to be a digital switching transistor...that is, package has builtin bias resistors to ensure it saturates as soon as base threshold voltage is reached (minimal rise/fall time)....and wrt the question 'what else could've fried?' ....well, I know there's an MCU on this board (display, I/O at a guess), and you hope they isolated it from this scenario...I got my crayons out, it looks a bit like this...   ...not a lot to see, or rather, everything you'd like to see disappears down a via to the other side...base drive for the transistor comes from somewhere else, what this transistor is switching is somewhere else...but the zener circuit is exclusive to all this ~ it's providing a set voltage (current limited by the 1K3 resistor R19)...and disappears somewhere else down the via I marked V out ; if the errant voltage 'jumped' the diode in the millisecond before it exploded, whatever that V out via feeds may have seen a spike... ....I'll just imagine that Q5 was switched off at the time, thus no damage should've been done....but whatever that zener feeds has to be checked... HTH
    • 25RBGT
      Got this r31 silhouette flood car to rebuild.

      By 25RBGT · Posted

      First time we have seen lights 
    • Wazmond
      WGNC34 - floor mats

      By Wazmond · Posted

      I think Fitmit had some, have a look on there (theyre Australian as well)
    • soviet_merlin
      Howdy Y'all

      By soviet_merlin · Posted

      Hah, fair enough! But if you learn with this one you can drive any other OEM manual. No modern luxury features like auto rev-matching or hillstart assist to give you a false sense of confidence. And a heavy car with not that much torque so it stalls easily. 
    • soviet_merlin
      WGNC34 - floor mats

      By soviet_merlin · Posted

      Actually, I'd say all three are the automatic option. Just the different trim levels. The manual would be RSFS, no? 
×
×
  • Create New...