Jump to content
SAU Community

Hunting Idle & Miss Fire ..... Advice Please?

stacky

By stacky,
in General Maintenance

 Share

Recommended Posts

stacky Apprentice

stacky

Posted
Posted

Hi all,

Have a series 1 R33 Gtst and have a few annoying problems that i hope someone can help me with....

Problem 1: Hunting idle & High tickover.

On first start up when cold it rev's quite high (normally between 1500rpm and 2000rpm) for the first 5(ish) mins.

Then when stopped at the lights, 50% of the time it idles stable at about 800rpm, but the other 50% of the time it hunts between 500rpm and 1500 rpm.

I did a search and found the two likely causes to be the idle control valve and/or the AFM.

I took both out yesterday and cleaned them with carb cleaner but NO DIFFERENCE :-(

Problem 2: miss fire when cold.

It missfires at from 4K plus when cold (not that i drive it all that hard when cold), but after a good 20min drive no more miss firing.

Finally,

The alternator belt or water pump bearing is screeching. Not sure if this is connected to the problems but thought i should mention it.

It does seem to play with the idle a tiny bit but as it only screches for the first 30 seconds of startup from cold - its obviously not the route cause.

Any help would be much appreciated.

Cheers

AGROV8D Newbie

AGROV8D

Posted
Posted (edited)

Try resoldering the AFM pins. Take out the AFM, open the box and resolder the pins going from the PCB to the loom connector.

Resolder them even if the old solder is still intact. You'll find that a lot of idle issues have been resolved simply by resoldering the connecting pins if you do a quick search (including mine, contacts were intact however I still ended up resoldering them just to rule it out and.it ended up fixing my idle issue).

Additionally, check that the AAC has been cleaned properly including mating surfaces and tightened properly when you reinstalled it. Check all the hoses going to and from the intake manifold for leaks.

Clean the throttle body and check/adjust the TPS to correct setting.

Reset the ECU and the idle once you've done all of the above. There is a step by step guide on cleaning the AAC and resetting the idle, do a quick search.

I have a feeling that your missfire issue is related to your idle problem so hopefully sorting out the idle will sort out the misfire.

Check the belts for wear, if worn, replace them. If not, check/adjust the tension, could be as simple as that.

Edited by AGROV8D
stacky Apprentice

stacky

Posted
  • Author
Posted

Thanks for the reply.

I will try re-soldering when I get a chance.

The acc was defo done correctly so I'm gona eliminate that from the possible causes list!

I'm gona wrap PVC insulation tape around the coil packs later to see if this cures the misfire (as per the sticky thread).

One thing I have not checked is the fuel filter so I'm going to change that tomorrow.

Any other opinions / suggestions?

AGROV8D Newbie

AGROV8D

Posted
Posted

Here's a couple of threads on how to adjust the TPS:

http://www.skylinesaustralia.com/forums/topic/404812-help-setting-tps-on-r33-s2/

http://www.skylinesaustralia.com/forums/topic/374524-rb25det-s2-tps-clarity/?hl=%2Badjust+%2Btps#entry5983578

stacky Apprentice

stacky

Posted
  • Author
Posted (edited)

Well, I adjusted the TPS. It was out but after adjusting correctly I still have the hinting / erratic idle issue.

Is it possible for the TPS to fail, or is that highly unlikely?

So far i have:

  • Adjusted the TPS.
  • Replaced the air filter,
  • Cleaned the AFM with electrical solvent cleaner.
  • cleaned the AAC

This weekend im going to do the following:

  • Replace the lambda/o2 sensor.
  • Resolder the AFM.
  • Oil change,
  • Fuel filter change.

I suspect however that none of that will fix the issue :-(

Anyone else have any other ideas??

PS.... currently the problems i am experiencing is:

When Cold:

  • Screeching belt on cold startup for the first 30 seconds.
  • Very high tick-over when cold (2000 rpm) but no hunting idle.
  • Miss fire at 4500 rpm.

When Hot:

  • Hunting/erratic idle (needle waves from 500rpm to 1200rpm).
  • Poor fuel consumption.
Edited by stacky
stacky Apprentice

stacky

Posted
  • Author
Posted

Ya, the belt is fine (its in good condition and probably less than a year old) so i figured it was just loose.

I tightened it using the adjuster on the alternator, started it up and it was screeching non stop, so then i slackened it off and it got alot better (but still screches when stone cold).

I need to budge and re-tilt the alternator bracket to slacken it off any further.

  • 4 weeks later...

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

    • Murray_Calavera
      "Cheap" bolt on turbo on RB25DET NEO

      By Murray_Calavera · Posted

      The fab work can be as simple as a couple of silicon hoses and clamps to the factory piping. 
    • joshuaho96
      "Cheap" bolt on turbo on RB25DET NEO

      By joshuaho96 · Posted

      Just sounds like either way you need to do some fab work to get everything to fit, so why limit yourself at that point? If the GCG high flow option is zero effort in and out swap though I'd probably do that. It's almost certainly lowest risk, lowest cost, etc. The HKS GTIII-RS option that Kapr mentioned is laughably expensive for what it is, they charge the exact same for two turbos on the RB26 so their margins are off the charts on that thing.
    • GTSBoy
      "Cheap" bolt on turbo on RB25DET NEO

      By GTSBoy · Posted

      Intake manifold is not a part of the issue. The turbo bolts to the exhaust manifold. That is easy. But close your eyes and picture the physical situation. That is a T3 flange on the manifold and a T3 flange on the turbo. As long as any new turbo has a T3 flange on the exhaust housing, that exhaust housing will bolt to the exhaust manifold. This places the exhaust housing in the same place as the stock one. But now move your mental attention a little further forward. The location of the compressor housing is set by the length of the turbo's core. The stock turbo had a long core. Let's say that it is..... 100mm long. So that would place the compressor housing 100mm forward of the exhaust housing. But a highflow, might well have a centre core that is shorter. Let's say that it is only 70mm long. Now the compressor housing will be 30mm further back in the engine bay than the stock one. This DOES move the turbo's compressor outlet backwards. It also moves the compressor's inlet backwards. You will very likely have to do some work to both the inlet and outlet piping to make everything connect again. I am not say this to make it out to be a bigger deal than it is. I am just pointing out that "bolt on" is sometimes not quite bolt on. The highflow from GCG that Murray linked above (https://gcg.com.au/turbo-charger-upgrade-skyline-gtst-2iu-xtrgts-s1.html ) uses a core that is the same length as the stock core, and so does not require this extra work. It will look very much like the stock turbo. No-one uses GTR turbos of any flavour (stock, or aftermarket) in a single turbo application on RB20/25. It's not a thing. Yes, people have been putting on GT3076, GTX3076 (and bigger and smaller versions of those) and G30s (of various sizes) onto RB20/25 since forever. But these are not "bolt on". Everything except the 4 bolts to the exhaust manifold change with these. And genuine Garretts are expensive. Non-gen, like Pulsar, etc, are cheaper, variously as good or nearly as good. But still not bolt on. No-one in the right mind would pay for an HKS turbo. Not in this modern day and age. Well, yes, the GCG highflow. You could ask HG what he can do to make the compressor housing sit in the original location. There are surely others doing highflows around the world. And some of the eBay/Temu ones (as reported by Dose) work and don't die. Bit of a lottery though. I would send your turbo to GCG (here in Oz) to be highflowed if you want a trivial no-extra-work option. But seriously, the work required to change inlet and outlet piping is not that hard. That's a boost control problem, not a turbo problem.
    • Kapr
      "Cheap" bolt on turbo on RB25DET NEO

      By Kapr · Posted

      Thank you all for the replys 🙂 I know that intake would be different but that is one pipe at it is not that hard to get(custom one). I meant mainly bolt to the stock manifold and the turbo elbow. I looked and many sites/forums but they are just "old" with some old HKS turbos from GT-R i guess? What about some Garrets?  Or any other turbo? Is there even a turbo which i can just bolt on? 😄 And yeah i know about that new HKS but that is like 2000k USD without taxes/shipping in here   Iam getting a touch up tune but my "problem" is that on the "not" hot day iam getting peaks around 0,9 bar...and when it was around 15 Celsious i saw peak around 1 bar which is just too much for stock turbo. And of course turbo is old and i like to get some new one for a piece of mind 🙂 
    • GTSBoy
      new here

      By GTSBoy · Posted

      I'm working on the assumption that our friend Jasmine here is a Russian (or, possibly Ukrainian) spammer/spambot, based purely on the number of such that I have been having to neuter in the last few weeks. IP address for the OP above was in WA. But that could have been via VPN. Posting at quarter to 4 in the morning is a good sign of being from somewhere in Europe. The last Jasmine that I kicked in the cooch was IP addressed in Ukraine. Even that could have been via VPN, and the bitchbot could have been from Russia, Serbia, China or anywhere. Regardless, was a spambot, so I killed it with fire. The fact that our new friend Jasmine here did not respond in any way to my tart query strongly suggests to me that this OP was just the establishment phase of a user able to be activated for spamming in a week, or 3 or 10.
×
×
  • Create New...