Jump to content
SAU Community

Car Not Holding Boost

Gunnar_11

By Gunnar_11,
in Engines & Forced Induction

 Share

Recommended Posts

Gunnar_11 Enthusiast

Gunnar_11

Posted
Posted

I was at Eastern Creek yesterday and had an issue with the car that ruined the day. I have no idea what this is but here's what happened:

Car would only rev to about 3.5 to 4k at 11psi; it is tuned for 16psi in this range. From there the car would flutter and not want to rev any more. The problem is, this only occurs under full load acceleration; with light acceleration it's happy to rev to red line.

I checked all the hoses and nothing was loose and couldn't hear any leaks.

It's an R33gts-t and does anyone have an idea what this may be because I've got nothing??

Link to comment
https://www.sau.com.au/forums/topic/317390-car-not-holding-boost/
Share on other sites
Duncan Grand Master

Duncan

Posted
Posted

I know you said you've checked all the hoses but that would still be my guess. On a track you are full load/full boost way longer than on the street, and things you might overlook can be loose.

so...check again....all clamps on the inlet....bov returns.....vacuum hoses....you need to look for splits as well as loose clamps too, tiny splits can open under boost but not be noticeable normally.

unless it sounds like a wrx of course!!

Gunnar_11 Enthusiast

Gunnar_11

Posted
  • Author
Posted

Thanks for your replies

Nah it didn't sound like a wrx. Car sounded normal and until it reached that flutter accelerated like normal.

I'll have to re-check all the hoses on it.

It's got after market coilpacks on it. I know it's an issue but how bad are these for going through coilpacks (as in after market ones)?

DVS JEZ Grand Master

DVS JEZ

Posted
Posted

what spark plug gap are you running?

my car was boost surging from 16psi to 13psi on sunday on the way to eastern creek, i worked out the boost controller was playing up, after turning the boost controller off and running stock boost the boost was fine,

is your boost surging or the engine missfiring/ spitting?

what fuel pump your running?

Gunnar_11 Enthusiast

Gunnar_11

Posted
  • Author
Posted

OK I've had another look through the car the other day. I made a mistake above and the car does hold 16psi when it does this.

Checked the exhaust to see if it was a blocked cat but when the exhaust was off the car did the same thing but only when it was at half throttle.

Checked and cleaned spark plugs - all okay.

Unfortunately I didn't check the coil packs when the spark plugs were off. I will check these though. There's Splitfires on there but I don't know how long they've been on the car for.

Any ideas on what else that may be wrong with the car?

RBceffy25 Rising Star

RBceffy25

Posted
Posted

Hey.

When did you last change your fuel filter? It may be partially blocked.

Gap your plugs to 0.8mm.

Also What voltage are you running with your pump? If it hasn't been done already, you need to wire it directly to your battery with a 30amp relay in place for correct operating voltage.

If you are using the stock AFM you may also need to change it.

RB25DET AFM's are temperamental things especially when compared to Z32 or even R32 and don’t like to run too much boost through them especially on cold days/nights.

What ecu are you running?

If its stock the problem may also be a factory safe guard known as ‘rich and retard’.

If you running Splitfire’s they should be fine but if you’re concerned have them tested.

All in all it’s just a process of elimination but to me it sounds like air/fuel ratios are out which is known to occur around this rev range on RB25DET which tells me its running rich.

I hope this may help you in some way.

Cheers.

Gunnar_11 Enthusiast

Gunnar_11

Posted
  • Author
Posted (edited)
Hey.

When did you last change your fuel filter? It may be partially blocked.

Gap your plugs to 0.8mm.

Also What voltage are you running with your pump? If it hasn't been done already, you need to wire it directly to your battery with a 30amp relay in place for correct operating voltage.

If you are using the stock AFM you may also need to change it.

RB25DET AFM's are temperamental things especially when compared to Z32 or even R32 and don't like to run too much boost through them especially on cold days/nights.

What ecu are you running?

If its stock the problem may also be a factory safe guard known as 'rich and retard'.

If you running Splitfire's they should be fine but if you're concerned have them tested.

All in all it's just a process of elimination but to me it sounds like air/fuel ratios are out which is known to occur around this rev range on RB25DET which tells me its running rich.

I hope this may help you in some way.

Cheers.

Thanks heaps for that info. I hadn't checked the pump to see for blackages yet; regarding the voltage, I'm not sure what it runs but I'd presume it would be wired in for the appropriate voltage. Will double check though.

I probably should have put these up earlier but these are the engine mods the car has done to it:

Apexi Power FC

GCG turbo

Deatchwerks Injectors

Hybrid front mount intercooler

Z32 air flow meter

HKS boost controller

Apexi pod

Custom metal intake pipe

Splitfire coilpacks

Ganador 3” exhaust

Catco metal cat 5” body

JJR aluminium radiator

Nismo fuel pump

I don't know how long they have been on the car for. It's putting out about 260kW at the wheels

Edited by Gunnar_11
RBceffy25 Rising Star

RBceffy25

Posted
Posted

Sweet man, nice set-up.

Get a volt meter and check your pump for sure. It should be running at about 13-13.5 volts at idle if it’s been wired correctly. I forgot to mention that it might also pay to get a can of CRC MAF/AFM cleaner. This shit works wonders.

Other than that, I would change fuel filter and plugs (coppers, 0.8mm) for security and take it to a dyno to check air/fuel ratios.

louie b Community Regular

louie b

Posted
Posted
I was at Eastern Creek yesterday and had an issue with the car that ruined the day. I have no idea what this is but here's what happened:

Car would only rev to about 3.5 to 4k at 11psi; it is tuned for 16psi in this range. From there the car would flutter and not want to rev any more. The problem is, this only occurs under full load acceleration; with light acceleration it's happy to rev to red line.

I checked all the hoses and nothing was loose and couldn't hear any leaks.

It's an R33gts-t and does anyone have an idea what this may be because I've got nothing??

still got the stock rubber in take? when they heat up they go soft an fold on them selfs stoping air flow

  • 2 months 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

    • Wazmond
      Stock rb25det neo questions

      By Wazmond · Posted

      Hows your intake piping? Are you still running stock? Having in the stock AFM position would mean, if the BOV was shut/venting out, it'd create the almost stalling kind of effect right // "the rich pulse behaviour" due to MAF thinking air is flowing ? But this would be better than having the bov in the stock position + MAF on/just before cross over piping right?
    • GTSBoy
      Stock rb25det neo questions

      By GTSBoy · Posted

      Essentially, yes. Although I wouldn't put the AFM on the crossover pipe. I'd want to put it into what amounts to the correct size tube, which is more easily done in the intercooler pipework. I bought a mount tube for card stile AFM that replaces the stock AFM - although being a cheap AliExpress knockoff, it had not flange and I had to make and weld my own. But it is the same length and diameter as the stock RB AFM, goes on my airbox, etc etc. I don't have a sick enough rig to warrant anything different, and the swap will take 5 minutes (when I finally get around to it and the injectors & the dyno tune).
    • Wazmond
      Stock rb25det neo questions

      By Wazmond · Posted

      So to summarise, the best thing to do is to move recirc to between turbo and IC, and maf on the crossover pipe. Meaning I'd need a recirc flange, drill a hole in the piping on turbo outlet area. And drill hole on crossover to fit/weld maf sensor? Either that or put the MAF on the turbo inlet right?  Is an aftermarket recirc/blowoff valve recommended? Do currently have family in Japan so could probably bring something back with maybe a cheeky lil SuperAutobacs run?
    • tsuokun
      Lets play a game - What is causing my oil consumption?

      By tsuokun · Posted

      Yep, so far most have said that it looks like corrosion on the wall from piston not moving. Which then has probably damaged the oil rings and caused those vertical marks. The longest the engine was still after the rebuild, was the winter of 2018 - 2019, plus the boat trip to Japan. When I shipped the car, it had normal gas in the tank but before that winter pause, it had E85 in tank.  In any case, even if either one of those was the cause, it happened close to 6 years ago and the car has been driven something like 30 000kms after the fact. Again, apart from the plugs and the dip stick, there is nothing in the way the car runs that would indicate what has been going on in the engine. I am going to consult a shop and ask their opinion, what would be the best approach. I do have some access to a garage I could use to diagnose further myself, but time is very restrictive. Might end up buying another engine that could be used while this one is being remedied. Without pulling the head, it will be impossible to find out if it needs another bore, but here's to hoping a hone would suffice.  Goddamnit, I would really have preferred this not happening.  
    • 25RBGT
      Got this r31 silhouette flood car to rebuild.

      By 25RBGT · Posted

      Boot is going to be replaced eventually. I just wire brushed what I could and rust converted. Then painted in rust kill primer. the spoiler also got repainted and plugs replaced on the ends. The under side of the bonnet is going to be black also, currently white. But red on the top side, same colour code as the silo to begin.
×
×
  • Create New...