Jump to content
SAU Community

Lumpy Idle

Primordial

By Primordial,
in Engines & Forced Induction

 Share

Recommended Posts

Primordial Grand Master

Primordial

Posted
Posted

My car has a very lumpy idle. At 700-900rpm the rocks around and the idle just feels lumpy.

Someone pointed to the fact that this may be a symptom of aftermarket cams.

Does anyone know of a way to check to see if my RB25 has got aftermarket cams? The car came with lots of other goodies on it, so I wouldn't be too surprised if they were non standard items.

Link to comment
https://www.sau.com.au/forums/topic/142867-lumpy-idle/
Share on other sites
Primordial Grand Master

Primordial

Posted
  • Author
Posted

Nah I havent checked this, but i do notice that at idle my car seems to burn a lot of fuel (black smoke out the exhaust).

I was poking around the engine bay this morning, and didnt notice anything out of place or loose - including the hoses/pipes...

Link to comment
https://www.sau.com.au/forums/topic/142867-lumpy-idle/#findComment-2662462
Share on other sites
Primordial Grand Master

Primordial

Posted
  • Author
Posted

I've had the car just over a year, and its been lumpy since I bought it. I've had the PFC tuned a couple of times so if there was something wrong (ie. vacuum leak) i think they guys would have picked it up..

It came with:

Apexi Turbo

Injectors

PowerFC

Fuel Pump

etc etc..

I suspect that its got cams due to the chunky mid-range. If I have a look at the cams, is there any way to tell if they are std or aftermarket?

Link to comment
https://www.sau.com.au/forums/topic/142867-lumpy-idle/#findComment-2662807
Share on other sites
Mr. Oizo Grand Master

Mr. Oizo

Posted
Posted
I suspect that its got cams due to the chunky mid-range. If I have a look at the cams, is there any way to tell if they are std or aftermarket?

They should have markings on them

I know HKS ones have a HKS logo and the duration on them, so I'm assuming Tomei and whatever other brands make cams would have it too

I'm not sure about regrinds though

Link to comment
https://www.sau.com.au/forums/topic/142867-lumpy-idle/#findComment-2662813
Share on other sites
T04GTR Grand Master

T04GTR

Posted
Posted
My car has a very lumpy idle. At 700-900rpm the rocks around and the idle just feels lumpy.

Someone pointed to the fact that this may be a symptom of aftermarket cams.

Does anyone know of a way to check to see if my RB25 has got aftermarket cams? The car came with lots of other goodies on it, so I wouldn't be too surprised if they were non standard items.

VCT solinoid

Link to comment
https://www.sau.com.au/forums/topic/142867-lumpy-idle/#findComment-2663161
Share on other sites
MR331307 Experienced

MR331307

Posted
Posted

Mate 1st 3 things ill check are

1) AFR`s on Idle (but seeing your saying its rich removes this but still check they should be around 14.4)

2) Vacuum leak (do you have a boost guage it should read 19 hg)

3) idle air control valve (check if this is leaking not working correctly)

Link to comment
https://www.sau.com.au/forums/topic/142867-lumpy-idle/#findComment-2663282
Share on other sites
amosite Proficient

amosite

Posted
Posted

If it has HKS Cams you will see HKS Cast into the cams by removing the oil cap and spinning it over a few times.

Unfortunately the duration is on the end where the cam gears bolt to and cant be seen easily. Only early HKS cams have them just under the HKS logo.

The tomei cams are stamped with serial numbers on the cam thrust washers. You might have to remove the rocker cover to see this one.

A couple of things to note.

Most GTST's have a baby smooth idle.

A 4'' exhaust will exhibit a bit of a lumpy idle but is more of a burble from the exhaust then engine idle

If cam timing is way out it can give the same symptoms

Probably the easiest guestimation is if your car has unusually strong mid/top end for the mods.

I imported a car a while back and it had stupid mid range even though it was on low boost at the time. I.e wheelspin in 1st and 2nd on 7 psi! Didnt think anything of it. I cleaned the TB and intake with upper engine cleaner a while later and it was running rough. I didnt remember what it originally ran like as I only drove it once and was away for 6 weeks OS so wasnt sure. Got my brother to look at it and he said it had cams, but sounds like the plugs are f&&*ed! Inspected through the oil cap and he said it had tomei markings on it- but there was no mention on the auction. I emailed a copy of the auction sheet and he said "it has tomei cams" but I couldnt translate/understand that part.

Which brings me to my last point. Once I put new plugs in it, ran a lot cleaner and smoother. Iriway and iritop plugs are great!

Link to comment
https://www.sau.com.au/forums/topic/142867-lumpy-idle/#findComment-2665553
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

    • TurboTapin
      R32 GTST - 600KW+ RB28/CD009 Build

      By TurboTapin · Posted

      Haha luckily we don't have emissions, inspections, or any laws against power adders here. They only thing they somewhat keep an eye out for are ridiculously loud exhausts. 
    • tidi0x
      CD009 RB Conversion

      By tidi0x · Posted

      Just wanted to pop in an update on my setup. The CD swap has been great, I love the mazworks housing for the overall simplicity. I ended up sealing my trans tunnel with a thin sheet of aluminum reused some of the holes on the trans tunnel, and laid some window sealing EPS foam around the edges. Works great, really quieted things down and sealed up the car.  As for the power comment. Right now I am also running about 650whp. with the way the bell housing is attached to the face of the transmission I have zero doubts it would be fine, mainly because the input shaft and main shaft bearings are seated into the bell housing adapter. This means the load is NOT on the bolts to maintain the power, rather into he casing of the bell housing; Yes the bolts are doing some work there, but with both shafts locked in zero worries.  End of the day, the Mazworks solution is the easiest and safest. no need to take your trans to a shop to get milled perfectly, it fits with minimal clearancing, and you can use all your existing clutch and flywheel.  Driving wise the CD has been great compared to the big box, I'll probably swap my final drive at some point. The serial 9 shifter is gooooood, my only qualm is how tight it is, it takes a fair bit to get use to, 5th and 6th are a bit eh/hard to find at times, but maybe I need re-adjusting, and I think my clutch master is very tired and needs a rebuild. 
    • Dose Pipe Sutututu
      Dumb rich kid tries modding for the first time

      By Dose Pipe Sutututu · Posted

      If you are keen, have a look at my build thread. Car is for sale for the right money or straight swap for a F80 M3 LCI.
    • Murray_Calavera
      Dumb rich kid tries modding for the first time

      By Murray_Calavera · Posted

      Welcome mate.  No point in over thinking it, buying any one of those cars you mentioned is not a smart or logical choice with the availability of many "better" (re price to performance) cars available to you.  The heart wants what the heart wants, buy whatever it leads you too.
    • Hexi
      Dumb rich kid tries modding for the first time

      By Hexi · Posted

      Hey everyone! Im so grateful to be apart of this community and ill do my best to be apart of this. Firstly, i'm not disclosing my real name due to in real life circumstances surrounding my privacy and public image (sorry lol) Secondly, The only thing personal I am willing to share is that I'm from Sydney and a descendant of one of Sydneys largest mortgage firms. I got gifted my first ever car, a 2022 Porsche Cayenne and I love it to death. Ive been driving it for about 5 or 6 months now and honestly Im so grateful for my parents for gifting me this vehicle. However recently I've been working my ass off to afford my second car (which I need help deciding soooooo community help me out please?). Once decided, im planning to try modify it myself. Recent I've been thinking about getting a Skyline, particularly a 25GT or GT-V, yes I know overrated as hell, but I'm also considering a Chaser which I recently came to love. However my dream is to one day own a 180SX (So hard to find clean versions and im not really into importing).  Lastly before I send this off, I want to apologize if I sound tacky or pretentious. I try not to and want to genuinely learn from everyone and anyone. (Im no expert in this area) Thanks for reading!
×
×
  • Create New...