Jump to content
SAU Community

R34 Rough Idle, Misfiring, Running Rich?

MarkB34

By MarkB34,
in Engines & Forced Induction

 Share

Recommended Posts

MarkB34 Rookie

MarkB34

Posted
Posted

Hey guys, this is my first post here but I've been reading for weeks now as I've been doing a complete engine swap on my car. Great to finally be a part of the skyline community

 

I bought my 2001 R34 GT about 3 months ago, and a month ago the radiator dumped coolant and the engine overheated and warped (didn't change temp gauge at all), and the car shut off completely and smoke billowed from engine. All sorted now with new engine in and everything seemed to be running fine. Took it on a long run 2 days ago and no issues at all, and everything seemed perfect minus the need for a tune. Last night I took it for a run on the freeway and I noticed that the tacho was pretty erratic jumping  about +-700rpm and a loss of power so I pulled over and the car shut off before I stopped and lost power steering similar to when the engine went. I managed to get a tow home and today I checked the plugs (all new from swap), and coilpacks for any damage (not sure if these are stock or not as they are blue, possibly Spitfires?) and didn't find anything. On idle the car is super rough misfiring and jumping around revs, when revving the car evens out at about 3000+, but backfires on decel and idle, even a little around 3000+. I tightened all clamps behind AFM (replaced old one with one from wreckers due to swap) and plan to swap back to the old one tomorrow and check if that fixes anything and also clean out the O2 sensor. Could the issue be a faulty injector possibly? 

Would connecting a scanner to the car produce any possible fault codes? Or would it just read no issue? 

The only thing I can think of in between it being perfect and the issue arising is that the car was washed but I doubt much water found it's way under the bonnet and the car ran fine for an hour or so afterwards. 

Thanks guys any help would be greatly appreciated.

  • Like 1
Link to comment
Share on other sites
Slap Rising Star

Slap

Posted
Posted

Could water have got in the tank.
Sounds like closed loop o2 to ecu isnt functioning correctly.wrong a/f mix readings.
By 3k its hittin maps usualy.
If its stock ecu unplug the o2 sensor leave it and do a reset and start it to see if idles and revs to 3k better.
Could be dirty maf also

Any mods we should know to help internet diagnoses?

Link to comment
Share on other sites
MarkB34 Rookie

MarkB34

Posted
  • Author
Posted (edited)
9 hours ago, Slap said:

Could water have got in the tank.
Sounds like closed loop o2 to ecu isnt functioning correctly.wrong a/f mix readings.
By 3k its hittin maps usualy.
If its stock ecu unplug the o2 sensor leave it and do a reset and start it to see if idles and revs to 3k better.
Could be dirty maf also

Any mods we should know to help internet diagnoses?

I heavily doubt water would have made its way into the tank

I'll give the O2 sensor a go today, cheers. I'll replace with the old AFM and clean the plug today too. Cheers mate

The only mods are a pod filter (have the airbox also, if that would possibly make a difference?) + a cat back exhaust. 

 

I reckon I've found the issue mate, the CAS disc was snapped and bent all over, I'm not sure how it happened though, would you know any causes? 

IMG_20190610_114158_01.jpg

Edited by MarkB34
  • Like 1
Link to comment
Share on other sites
Slap Rising Star

Slap

Posted
Posted

Wow. I havent seen that before. Definitely an issue. I cant believe it ran clear at 3k.

Unless you broke the disc by accident opening it up. ( doughtful ).

Got another cas?

Link to comment
Share on other sites
MarkB34 Rookie

MarkB34

Posted
  • Author
Posted
5 minutes ago, Slap said:

Wow. I havent seen that before. Definitely an issue. I cant believe it ran clear at 3k.

Unless you broke the disc by accident opening it up. ( doughtful ).

Got another cas?

Me either, I am shocked that it didn't run worse. I've ordered another one, should be here mid week, just concerned it will happen again. Definitely will get it tuned asap, to be sure

Thanks mate

Link to comment
Share on other sites
MarkB34 Rookie

MarkB34

Posted
  • Author
Posted

Just the stock ecu at the minute. When I did the swap I checked it before reinstalling and it was definitely not that bad. It had a slight bend but that was it, could it have just bent too far and caused the chipping and cracks? 

Link to comment
Share on other sites
Slap Rising Star

Slap

Posted
Posted

Stock ecu should just need a reset unless u got nistune in it.
Have you driven another turbo skudline?
If not maybe it wasnt running correct at 3k+ and never experienced its hidden truth.

I just cant see it running right at all if that disc was like that the whole time.

New cas . Reset . Away you go hopefully. Goodluck! And becareful cause it may have loads more power than previous.

Link to comment
Share on other sites
MarkB34 Rookie

MarkB34

Posted
  • Author
Posted

I doubt the car has a nistune, I've already reset the ecu before and everything ran fine. I haven't driven another turbo skyline, but I'm unsure as the CAS seemed in pretty decent nick when I first looked at it

Hopefully when it arrives I can just plug and go, straight to the tuners. Cheers mate, you too

Link to comment
Share on other sites
Slap Rising Star

Slap

Posted
Posted

You cant tune the stock ecu.
You will need an aftermarket one and if your auto one that can assist the auto.

I doubt the car has a nistune, I've already reset the ecu before and everything ran fine. I haven't driven another turbo skyline, but I'm unsure as the CAS seemed in pretty decent nick when I first looked at it
Hopefully when it arrives I can just plug and go, straight to the tuners. Cheers mate, you too
Link to comment
Share on other sites
MarkB34 Rookie

MarkB34

Posted
  • Author
Posted

Okay, so I replaced the CAS tonight and the car ran and made it around the block, the timing is slightly off as it has a rumble quite low in the revs and on takeoff. Will adjusting the positioning of the CAS make a difference or should I wait until I get it to a tuner to go over it properly? 

Thanks again guys

Link to comment
Share on other sites
Slap Rising Star

Slap

Posted
Posted

If you are going for an aftermarket ecu then yes.

If not you cant get it tuned . Just serviced, fixed or modded.

But definitely dont play with it.
Make sure it gets timed correct.

Link to comment
Share on other sites

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

    • GTSBoy
      Does anyone know whats happening with harness on drivers door?

      By GTSBoy · Posted

      The two diagrams are equivalent. The R32 one is just one sheet out of about 3 showing everything in the whole car all at once. And without knowing the functionality that occurs in the modules, they are both equally opaque.
    • Neostead2000
      R35 OEM Injector dead times

      By Neostead2000 · Posted

      8v - 2.48ms 9v - 2.15ms 10v - 1.74ms 11v - 1.41ms 12v - 1.15ms 13v - 0.99ms 14v - 0.89ms 15v - 0.82ms 16v - 0.81ms I'm running these values on my RB20 Neo with 570cc Denso R35 stock jets and it's great. Also bought a set for my Legnum VR4, love these injectors!
    • harambe34
      Does anyone know whats happening with harness on drivers door?

      By harambe34 · Posted

      Thanks for your reply,  Those blue/green wires running to the actuator aren't attached to anything, so I'm not sure how the central locking is still working. I will have to take a good look tomorrow, I don't have the car with me. After googling it seems like a pretty common aftermarket actuator which even uses the same green/blue wires the immobiliser required. i'll test everything tomorrow and if it's working i'll melt the solder, strip it, resolder and neaten it all up with some heat shrink. I don't have to understand it if it works hahaha I just don't want a fire/ short circuit. That R32 diagram looks more like a continuity chart? Can you make sense of this form the R34 manual? 10V is probably due to very flat battery, i'll recheck as well tomorrow, I did have to jump start it haha. Thanks again!  
    • GTSBoy
      Does anyone know whats happening with harness on drivers door?

      By GTSBoy · Posted

      So, COM doesn't mean comms. It means common. What common itself means will depend on the type of device. For a two directional actuator (ie, one that can push and pull on the same output rod) then the common will typically just be the earth connection. There will be at least 2 other wires. If you put 12V on one of the other wires, then the actuator will push. On the other 12V wire, it will pull. Can't quite make out what is going on with the wiring of your actuator. It appears to have several wires at the actuator plug, but there only appears to be 2 wires where its loom approaches the door control module, with at least one of the others cut off. I don't know these actuators off by heart. I'd have to look at a wiring diagram for one before knowing what the wires were about, and that's despite me having to replace one in my car not all that long ago. Just not interesting enough to have dedicated memory set aside for trivia like that any more. That actuator is an aftermarket one, not the original one, which probably died and was replaced. That might require some sort of bodge job on wiring to make it work. Although nothing should justify the bodginess of the bodge job done. As to the soldering job on the door module's loom plug. Ahhahhahaha. Yes, very nasty. Again, I cant tell you what any of those wires do. You'd need to study the R34 wiring diagram (if you can find one that shows the door module). I don't think I have any. I'd have to study the R32 diagram to start to understand what mine is doing, and again, even though I've had a problem with mine for the last 25 years (where it locks the passenger door when the driver's window reaches top or bottom of travel) I'm just not interested enough to try to to work it out. So long as it's not burning down, it's fine with me. Here's the R32 GTR diagram, which, confusingly, has rear door lock actuators and window motors on it!! As you can see, unless you understand the functions of the door lock timer and the power window amplifier, you'll never be able to work out how it works just from the diagram. I don't imagine that the R34 one is any better. Hopefully an R34 aware bod can help. FWIW, the two wires that are cut and joined look like they are both power supply - so hopefully it is not fatal to join them. The 10V you measured on the cut off free end of one of them is concerning. You'd expect 12V, and it might be the reason for the bodge job joining them together.
    • harambe34
      Does anyone know whats happening with harness on drivers door?

      By harambe34 · Posted

      Oops my bad, here you go .
×
×
  • Create New...