Jump to content
SAU Community

Need Info Regarding A Tough Rough Idle

SargeRX8

By SargeRX8,
in General Maintenance

 Share

Recommended Posts

SargeRX8 Grand Master

SargeRX8

Posted
Posted

Hey all,

Its been some time since I've posted here but I'm at it now and I need some direction. This ones got me stumped.

My car has, for quite some time now(more than a year), been idling poorly. In a nut shell.

In more detail, the car will never start first go in the morning unless I'm lucky and mashing the throttle or its a warm/hot day. No idea if this is related but lets move on. When my car does start and run while its cold, its perfect, revs hold fine until it warms and they come down to the normal range. I can then go on my drive, 5 minutes to 1 hour what ever it is and more often than not my revs will not be stable. If I watch the needle closely I can see the needle jitter as well as hear it in the engine and see it in the vacuum gauge.

Today it was significantly worse. My car pulls a nice high amount of vacuum, usually at -28 to -30 on my boost gauge and -96 on my Profec B spec 2. Today it decided to pull between -20 and -24 and -76 and my revs came down to about 700 and were fluctuating between 700 - 780. It was audibly noticeable. I thought I may have popped off a hose or something so I pull over and listen over the whole engine bay and it sounded just fine. I gave it throttle and there was no sign of boost leak either.

I really don't know where to go with this. I do not run a O2 sensor and my car has all the bolt ons(mods below). I have no idea where to go from here. I don't know if this is a vacuum leak since it doesn't happen all the time. Another thing to note is I have ran 100octane E10 fuel from United over at Drummoyne. That stuff is awesome. I know people hate it but I've ran probably 3 tanks of that stuff and I get more KM's and it seems to kick my knock out the window.

The AAC valve has been cleaned, the plenum gasket is fresh as the old one busted out. The TB to plenum gasket is fresh. I need a second set of ears as I suspect there MAY be a leak somewhere under the plenum but for the life in me I can not locate where the sound is coming from and spraying gas in the area does not cause the revs to change. If anyone can make any suggestions as to where I can start looking with this, that would be great.

Also to throw this in there, the other day when I started my car in the morning the engine light came on for about 3 seconds and the moment it came on I heard a lean pop from the exhaust. I have no idea what caused the light to come on. It has happened once in the past for about 3 seconds while driving and during that 3 seconds the car ran like absolute dog shit.

The car is an R33 GTST with the following:

Unopened RB25DET

Power FC

740cc nismo injectors

Z32 afm

HG SS2

3" to 4" exhaust

Enclosed Pod

Thanks all!

Ben C34 Grand Master

Ben C34

Posted
Posted

Check for vacuum leaks.

Easiest way is by pressure testing. Then you can hear the leak and spray soapy water if needed to make it even easier to find.

Have you ever checked the timing?

AngryRB Grand Master

AngryRB

Posted
Posted (edited)

sounds like what I experienced with mine, the intake manifold is warped and would never seal properly, squrt some carby cleaner on the plenum gasket and see what happens, mine was playing

games with me cause it seemed to run ok but then at times it would just stall when starting or reversing, also when I converted to E85 the cold start was too lean and gave stalling when cold.

Edited by AngryRB
SargeRX8 Grand Master

SargeRX8

Posted
  • Author
Posted

I haven't checked the timing since it was done nearly two years ago as I don't have a timing light. Part of me thinks it may be something to do with the CAS but I don't know if a CAS issue wil throw a check engine warning.

I'll do a pressure test this weekend after I make a new jig. I can't find the old one.

I really hope its not a warped anything. I'm gonna go over it again and tighten everything around the plenum up, I remember changing the gasket there and the thing was an absolute bitch to do and it was summer. Maybe I didn't apply enough tension to a screw.

I don't know how to determine if the check engine light is related to this issue since the check engine has only happened twice in about 3 - 4 years of owning the car.

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

    • 04-LOOX
      R34 GTR Vspec Garage Sale - All must go!

      By 04-LOOX · Posted

      Hi, is the HKS  Tower Bar still available ? negotiable ? 🤔
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      From there, it is really just test and assemble. Plug the adapter cables from the unit into the back of the screen, then the other side to the car harness. Don't forget all the other plugs too! Run the cables behind the unit and screw it back into place (4 screws) and you should now have 3 cables to run from the top screen to the android unit. I ran them along the DS of the other AV units in the gap between their backets and the console, and used some corrugated tubing on the sharp edges of the bracket so the wires were safe. Plug the centre console and lower screen in temporarily and turn the car to ACC, the AV should fire up as normal. Hold the back button for 3 sec and Android should appear on the top screen. You need to set the input to Aux for audio (more on that later). I put the unit under the AC duct in the centre console, with the wifi antenna on top of the AC duct near the shifter, the bluetooth antenna on the AC duct under the centre console The GPS unit on top of the DS to AC duct; they all seem to work OK there are are out of the way. Neat cable routing is a pain. For the drive recorder I mounted it near the rear view mirror and run the cable in the headlining, across the a pillar and then down the inside of the a pillar seal to the DS lower dash. From there it goes across and to one USB input for the unit. The second USB input is attached to the ECUtec OBD dongle and the 3rd goes to the USB bulkhead connected I added in the centre console. This is how the centre console looks "tidied" up Note I didn't install the provided speaker, didn't use the 2.5mm IPod in line or the piggyback loom for the Ipod or change any DIP switches; they seem to only be required if you need to use the Ipod input rather than the AUX input. That's it, install done, I'll follow up with a separate post on how the unit works, but in summary it retains all factory functions and inputs (so I still use my phone to the car for calls), reverse still works like factory etc.
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      Place the new daughterboard in the case and mount it using the 3 small black rivets provided, and reconnect the 3 factory ribbon cables to the new board Then, use the 3 piggyback cables from the daughterboard into the factory board on top (there are stand offs in the case to keep them apart. and remember to reconnect the antenna and rear cover fan wires. 1 screw to hold the motherboard in place. Before closing the case, make a hole in the sticker covering a hole in the case and run the cable for the android unit into the plug there. The video forgot this step, so did I, so will you probably. Then redo the 4 screws on back, 2 each top and bottom, 3 each side and put the 2 brackets back on.....all ready to go and not that tricky really.      
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      Onto the android unit. You need to remove the top screen because there is a daughterboard to put inside the case. Each side vent pops out from clips; start at the bottom and carefully remove upwards (use a trim remover tool to avoid breaking anything). Then the lower screen and controls come out, 4 screws, a couple of clips (including 3 flimsy ones at the top) and 3 plugs on the rear. Then the upper screen, 4 screws and a bunch of plugs and she is out. From there, remove the mounting brackets (2 screws each), 4 screws on the rear, 2 screws top and bottom and 3 screws holding in the small plates on each side. When you remove the back cover (tight fit), watch out for the power cable for the fan, I removed it so I could put the back aside. The mainboard is held in by 1 screw in the middle, 1 aerial at the top and 3 ribbon cables. If you've ever done any laptop stuff the ribbon cables are OK to work with, just pop up the retainer and they slide out. If you are not familiar just grab a 12 year old from an iphone factory, they will know how it works The case should now look like this:
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      Switching the console was tricky. First there were 6 screws to remove, and also the little adapter loom and its screws had to come out. Also don't forget to remove the 2 screws holding the central locking receiver. Then there are 4 clips on either side....these were very tight in this case and needed careful persuading with a long flat screw driver....some force required but not enough to break them...this was probably the fiddliest part of the whole job. In my case I needed both the wiring loom and the central locking receiver module to swap across to the new one. That was it for the console, so "assembly is the reverse of disassembly"
×
×
  • Create New...