Car Not Holding Boost

[Gunnar_11]

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??

[SS8_Gohan]

coilpacks breaking down perhaps??

did it sound like a wrx?

[Thelen]

Sounds like fuel cut. If its fine on the street but not on track, might be fuel starvation..

[Duncan]

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]

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]

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]

Not sure about the spark plug gap.

This might sound weird but it sounds like boost surging however the guage remains at a constant 11psi (ie there's no fluctuating of boost)

Running a Nismo fuel pump

[Gunnar_11]

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?

[nsmo30tt]

mmm.. sounds like an issue related to air.. im meaning vacuum hoses ect.. but also maybe tps?

[RBceffy25]

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]

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 April 26, 2010 by Gunnar_11

[RBceffy25]

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]

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

[Gunnar_11]

Ok so the coil packs and spark plugs were replaced last night; it's helped the problem but not fixed it, still doing it but it's doing it over less RPM.

Going off the Apexi hand controller the AFM's seem ok.

Anyone have ideas on what else to check???