Jump to content
SAU Community

Occasional Miss Or Lump On Idle

sturb25

By sturb25,
in Four Door Family & Wagoneers

 Share

Recommended Posts

SMOKEYV35 Mentor

SMOKEYV35

Posted
Posted (edited)
What is this PCV valve is it present on standard RB's and Neo's or what?

PCV valve is positive crankcase ventilation valve. most cars have them - they basically release any buildup of combustion gasses that sneak past the piston rings and in under the cam covers. this is also called 'blowby'.

the PCV is the factory way of releasing that pressure. the valve opens when the crankcase is under positive pressure, releasing the gasses and any oil vapour back into the intake where it cycles back into the engine and is burnt off in the next combustion cycle.

a way that tuner's approach this is to get rid of this system and run a breathable catch can - which vents that vapour to the atmoshpere naturally, and then using a series of baffles, attempts to get the oil particles out of the vapour, where the accumulate in the bottom of the catchcan to be drained later. because it is unmetered exhaust releasing to atmosphere, they're illegal.

after that explanation, i'd be curious to see how he thinks the PCV is contributing to the miss. unless it is sticking shut, and then snapping open and releasing a big pressurised hit back into the intake - but that could only upset the AFR if it was entering the intake before the AFM?? either way, it's easy to eliminate the possibility just remove the return pipe from the intake and plug the intake hole with your thumb. if its still doing it, it's not your problem!

EDIT: just thinking this over in the back of my head, it could be stuck - yes. but it could be stuck OPEN, which would cause a vaccum leak and create a lean misfire. to check this, take the hose off at the PCV valve, and block the PCV valve with your thumb. all in all, pretty quick checks!

and if you just want to service it for peace of mind, grab some throttle body cleaner (carby cleaner) and remove the PCV. soak it in a cap full of the stuff. shake it round a bit and it should start moving freely again. do your throttle body while you're at it.

Edited by SLYLINER
Brendan&Ana Collaborator

Brendan&Ana

Posted
Posted

EDIT: just thinking this over in the back of my head, it could be stuck - yes. but it could be stuck OPEN, which would cause a vaccum leak and create a lean misfire. to check this, take the hose off at the PCV valve, and block the PCV valve with your thumb. all in all, pretty quick checks!

and if you just want to service it for peace of mind, grab some throttle body cleaner (carby cleaner) and remove the PCV. soak it in a cap full of the stuff. shake it round a bit and it should start moving freely again. do your throttle body while you're at it.

thats basically what the mechanic has said but he told me to just buy a new 1 cause it should be pretty cheap and throttle body and injectors have already been cleaned

Brendan&Ana Collaborator

Brendan&Ana

Posted
Posted
Just tried cleaning mine and still no joy.

Going to go get a new set of plugs (even though these only done 2,500) sometime soon

when i went to mechanic he cleaned mine aswell it was fine for a lil while then came back but he did say i need to replace it

  • 2 weeks later...
kidafa Veteran

kidafa

Posted
Posted

Turns out my issue was my timing on base idle was well out... I should have chucked the light on it ages ago but its been with a mate! Dialed it in on the dyno today and shes happy again :-)

  • 1 month later...
sturb25 Proficient

sturb25

Posted
  • Author
Posted

Replaced my plugs with coppers today, the miss on idle has gotten worse but it seems to be smoother on and off throttle especially noticable whilst going down hill. Am going to replace o2 sensor in a couple of weeks, i havent ever replaced it and its done 160,000km now.

This miss has got to be sorted out, its starting to shit me. The last time it was this bad was about two years ago and i tracked it down to the hose that crosses over the rocker covers at the front having a split in it. Maybe it is a hose.

When u sit there with your foot resting on the throttle giving it a flat constant rev at one rpm anywhere in the rev range its got a miss but you dont feel it when your driving.

sturb25 Proficient

sturb25

Posted
  • Author
Posted
Replaced my plugs with coppers today, the miss on idle has gotten worse but it seems to be smoother on and off throttle especially noticable whilst going down hill. Am going to replace o2 sensor in a couple of weeks, i havent ever replaced it and its done 160,000km now.

This miss has got to be sorted out, its starting to shit me. The last time it was this bad was about two years ago and i tracked it down to the hose that crosses over the rocker covers at the front having a split in it. Maybe it is a hose.

When u sit there with your foot resting on the throttle giving it a flat constant rev at one rpm anywhere in the rev range its got a miss but you dont feel it when your driving.

How do you reset the ecu?

  • 1 month later...
sturb25 Proficient

sturb25

Posted
  • Author
Posted

Yay, my cars miss is all sorted out. Took it to the mechanics about 2 weeks ago and they said the timing was out 4 degrees so they adjusted that and cleaned the air flow meter but the miss was still there, slightly better but still there.

They checked a few more things but couldnt figure out why it was there. They said the only thing they could think it would be is a dirty injector, so i pulled them out and had them tested and cleaned and re-tested.

The injectors came up 10% difference between the lowest and the highest pressure, the spray and spray angle was good. They got them within 2% from highest to lowest after cleaning them. There tolerance is 3%

My car has never sounded so smooth, no more popping. Its actually gotten quieter, Im wrapped

DaveB Mentor

DaveB

Posted
Posted

Yay, my cars miss is all sorted out. Took it to the mechanics about 2 weeks ago and they said the timing was out 4 degrees so they adjusted that and cleaned the air flow meter but the miss was still there, slightly better but still there.

They checked a few more things but couldnt figure out why it was there. They said the only thing they could think it would be is a dirty injector, so i pulled them out and had them tested and cleaned and re-tested.

The injectors came up 10% difference between the lowest and the highest pressure, the spray and spray angle was good. They got them within 2% from highest to lowest after cleaning them. There tolerance is 3%

My car has never sounded so smooth, no more popping. Its actually gotten quieter, Im wrapped

That's a great result, glad to hear. I actually developed a slightly rough idle after going to 600cc injectors (neo); this was apparently to do with not having quite enough resolution in the latency settings. It doesn't bother me; sounds kinda 'tough', and for the increase in power I'll tolerate it :)

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

    • Sean'O
      3D printing fun

      By Sean'O · Posted

      Howdy friends, So another weird one today, I was looking into replacing some broken clips holding the front grille for the R32 GTR (part number 01553-03831), and noticed the brackets which are supposed to hold the grille in place were also missing 😑. I do recall seeing this issue many years ago, but didn't fix it at the time. A quick look on eBay and I was able to find the genuine brackets, along with all the screws which suited the headlights (part numbers 26042-08U05,26092-08U05). Happy days!....  Once they arrived however there was an extra nut in the packaging which implied that there should also be a bolt or a stud, and sure enough, after a bit of searching I found this thread from 2013, and @Ants clearly shows a stud should be present. Reading around a bit more, it's possible the headlights on my car are the "povo pack" headlights as mentioned by @funkymonkey in this thread way back in 2008. This could explain why the studs are missing on my set of headlights. Looking at the headlight diagram I wasn't able to see a suitable part number for the stud itself. The headlight did indeed have a recess that looked like it would accept a stud, but interestingly no thread or anything obvious how the stud would be affixed to the headlight, I suspect it may have been glued in, press fit, or melted into the plastic at the factory. Another member may be able to clarify if they happen to have a genuine set of N1 headlamps. The only thing we have to work with within the recess is a keyway which likely is there to prevent the stud from rotating within the recess. In any case, back to 3D printing, I put together a model which acts like a pug with a friction fit inside this recess, making use of the keyway so it doesn't rotate while tightening a bolt. Printing in TPU will allow it to slightly swell making a nice snug fit without cracking the part. I've designed the adaptor it to accept an 20 mm M6 bolt (stainless with a cap head in my case), as opposed to the standard M5 stud and I made use of the standard galvanised split washer that came with the genuine brackets from Nissan. Once the bolt and screws were all in place, giving the bracket a gentle shake gave the classic "shaking the car" feeling, very solid, which gives me confidence this is going to be able to hold on much better than the janky solution which seems to have been here for the past decade or so. Overall I'm really pleased with how this turned out and maybe there are more people out there running these headlights without a centre stud at all! Link to the freely available model on Printables: Click here Regards, Sean  
    • GabsReDeal
      R32 GTS (RB20DE) clogged cat

      By GabsReDeal · Posted

      Hey everyone, This is my first post apart of the introduction. I tried searching a bit on the forum but couldn't really get a straight answer. I got the car to my mechanic as I felt it being weak. It seems that it was missing on two cylinders due to the injectors. I had all my injectors clean and the car runs much better. The mechanic also confirmed my suspicions that the cat is clogged and needs to be tackled asap. The cat rattles a bit and the hot exhaust warning frequently lights up when driving after getting the injectors clean. In my introduction I was asked about what modification I might be interested in and mentioned a cat delete. From what I was told, this is not really beneficial on the RB20DE and there are more cons than pros.  Could perhaps anyone give some suggestions on what the best course of action would be since the current cat is toast and needs to be removed/replaced anyway? I can also sometimes smell a strong smell of fuel, but I'm not sure if this is related.
    • Milkmun
      NC MX5

      By Milkmun · Posted

      Hope the cans went down well at least 
    • Milkmun
      Neil's R33 Gts-t Build

      By Milkmun · Posted

      255 can't go wrong with the price.
    • Kinkstaah
      Neil's R33 Gts-t Build

      By Kinkstaah · Posted

      When I was replacing my pump due to being stranded in the wrong state, I went with the Deatschwerks 320lph kit. It is a direct plug in to the stock wires, harness, everything. It comes with a plug... but you can plug the OEM plug directly into this thing. https://justjap.com/products/deatschwerks-dw300-fuel-pump-nissan-s13-silvia-r32-r33-r34-skyline-c34-stagea?currency=AUD Downside: Won't actually flow that much on boost if you want to push it on E85, but it's comparable to the 040/255 etc. Little more actually.
×
×
  • Create New...