R33 GTST weird idle?

[Beardrive]

Hey idk if im just paranoid but after a track day i have the feeling that the car has a weird idle. It sounds a bit like a rotary or Subaru. If i blip the throttle it sounds a bit like fuel igniting in the manifold. 

It feels strong and pulls well tho so it doesn't seem like a missfire

I just have an Apexi intake and exhaust system, combined with a blitz sequential boost controller. Running max 0.7 Bar

[joshuaho96]

3 hours ago, Beardrive said:

Hey idk if im just paranoid but after a track day i have the feeling that the car has a weird idle. It sounds a bit like a rotary or Subaru. If i blip the throttle it sounds a bit like fuel igniting in the manifold. 

It feels strong and pulls well tho so it doesn't seem like a missfire

I just have an Apexi intake and exhaust system, combined with a blitz sequential boost controller. Running max 0.7 Bar

Start with an idle power balance test. Consult cable will let you shut off fuel to one cylinder at a time without having to risk breaking an injector harness clip or have the metal clip go flying off into the abyss. 

[Murray_Calavera]

5 hours ago, Beardrive said:

It sounds a bit like a rotary or Subaru

If it actually sounds like this, could be a blown head gasket. Not having any overheating issues are you?

[Beardrive]

7 hours ago, Murray_Calavera said:

If it actually sounds like this, could be a blown head gasket. Not having any overheating issues are you?

it got a little bit over the middle of the temp gauge on the track but not really overheating. 

[Beardrive]

9 hours ago, joshuaho96 said:

Start with an idle power balance test. Consult cable will let you shut off fuel to one cylinder at a time without having to risk breaking an injector harness clip or have the metal clip go flying off into the abyss. 

I dont have a consult setup. Is there another way to do this?

[Kinkstaah]

It sounds like a misfire. RB's go surprisingly good on 5cyl.

The easiest way is to have your car idling, and unplug a coilpack or an injector and see/find which one doesn't make the sound change. That's your problem cylinder. The consult cable means you don't have to actually unplug stuff, can turn it off electronically.

[Beardrive]

ah ok I was about to record a video but the battery is completely empty. I'll charge it up later and upload the vid. Hopefully its just the coils since i planned to get splitfires anyway

[Beardrive]

8 hours ago, Murray_Calavera said:

If it actually sounds like this, could be a blown head gasket. Not having any overheating issues are you?

I checked the usual things for headgasket like color of coolant/oil and if the oil filler cap has that milkshake stuff but everything looks good

[joshuaho96]

1 hour ago, Beardrive said:

it got a little bit over the middle of the temp gauge on the track but not really overheating. 

That is pretty much overheating on an RB. Should never exceed middle of the temp gauge. In my experience normal temp it never even gets to the middle reading 80C.

[Beardrive]

16 minutes ago, joshuaho96 said:

That is pretty much overheating on an RB. Should never exceed middle of the temp gauge. In my experience normal temp it never even gets to the middle reading 80C.

Really? i mean im bot from Australia so its summer here rn. We had 35°C and I was beating on it quite a bit. When i did a chill cool down lap with normal driving it very quickly dropped down to normal

[GTSBoy]

30 minutes ago, Beardrive said:

Really? i mean im bot from Australia so its summer here rn. We had 35°C and I was beating on it quite a bit. When i did a chill cool down lap with normal driving it very quickly dropped down to normal

What Josh was saying is that the stock gauge reads dead on centre across a really wide range of temperatures, from "not quite up to operating temperature" all the way to "you're just about to cook it". That means that if you ever see the gauge over the 50% mark it is actually very bloody hot, and yes, you might have done the gasket at that time. Or, you might not.

Head gaskets can fail so that coolant enters the cylinder, exhaust gases enter the coolant, oil enters the coolant or water enters the coolant, or any of the possible combinations. Just not seeing emulsified oil in the radiator is not sufficient to rule out gasket failure. You also need to test the coolant pH, to look for dissolved combustion gases (CO2 -> carbonic acid when dissolved in water).

A fluffy idle could be from a dying/dirty injector, dying coilpack (or perhaps damaged sparkplug), a vacuum leak on the inlet manifold gasket, broken piston/ringlands or burnt exhaust valve, and any of a number other things. You need to start working through the list.

[Kinkstaah]

FYI. I have a R34, not a R33.

I noticed that the stock gauge would be middle at 104C. Then completely pegged to H at 105. It moves gradually between middle and hot, it physically takes time to move. (same as it takes time to move from cold to OK)

It only has 3 actual settings, "Too cold", "OK" and "Too Hot"

[Beardrive]

i ordered a head gasket test kit to make sure its not that.

I could test the injectors and Coilpacks by unplugging them and see if the idle Changes? 

Id check for A vacume leak by spraying break clean and see if the idle changes? 

i have an endoscope for checking the valves. 

What can i do to check Ringlands. 

Have I forgotten any test i should do?

I'll upload a video of the idle later after work/charging the battery

 

 

 

 

 

[GTSBoy]

3 hours ago, Beardrive said:

i have an endoscope for checking the valves. 

What can i do to check Ringlands. 

You can't do a really convincing examination of either the valves or the pistons (through the plug hole) with an endoscope. You can have a look, but it is difficult to see everything.

[MBS206]

Disconnecting a coilpack/injector isn't 100% on identifying anything other than the suspect cylinder.

 

If doing it you note one in particular makes no difference at all, you've got a total miss on that cylinder, it could still be for numerous reasons.

If you do it, and one cylinder affects the idle less than all the others, now you t least have a suspect cylinder.

I'd be doing a compression check on all cylinders first up.

If they're out of spec, do a leak down on it too.

 

Secondly, grab a video of this idle and stick it up here.

[Beardrive]

I'll do a compression test on the weekend with the headgasket test. 

here is a youtube like with the idle:

 

 

 

 

 

 

 

[Beardrive]

I just remembered I got like intermittent rpm drops on idle a couple weeks ago but that's gone now 

[GTSBoy]

Sounds fine.

[silviaz]

On 7/10/2024 at 4:30 PM, Kinkstaah said:

It sounds like a misfire. RB's go surprisingly good on 5cyl.

The easiest way is to have your car idling, and unplug a coilpack or an injector and see/find which one doesn't make the sound change. That's your problem cylinder. The consult cable means you don't have to actually unplug stuff, can turn it off electronically.

I thought I heard if you do this it can drop a cylinder?

[Beardrive]

1 hour ago, GTSBoy said:

Sounds fine.

so I was just paranoid and it's alright?