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Sick R34 - Pfc Problem?

Bill

By Bill,
in Engines & Forced Induction

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Bill

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Lately my R34 GT-T has started knocking under medium load. (Moderate accelleration uphill)

It seems to be down on power and chewing through more fuel, I only got around 500k from the last tank.

I had a basic service last week, but if anything its gotten a little worse.

When it origionally started happening I thought it may be a bad batch of fuel, but that was several tanks ago now and its slowly getting worse.

I was wondering if its possible for a PFC to loose its tuning, and if so, how to tell?

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https://www.sau.com.au/forums/topic/189995-sick-r34-pfc-problem/
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Bill Collaborator

Bill

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just take it back to the tuner and ask him to take a look. maybe timing needs to be changed marginally due to the heat.
It hasent really heated up out here yet, nothing like summer which was fine, and same knocking problems in the morning when its quite cool still.

I spose I will have to make a Trip to Sydney to visit a Tuner.

Also, geez bud, only 500 km??what do you normally get??
Normally 45L for 500k, this time it was 54L for 500k.

(most of my driving is commuting to work which is pretty much just hightway cruising.)

Bill Collaborator

Bill

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omg.... you get 500kms a tank on a highway is about right, you're complaining?

My main concern is "has started knocking under medium load."

As for the fuel economy, I would think noting that Its started using 9L more per 500km may be useful information to working out whats gone wrong dont you?

What mods you running?

FMIC, PFC, Eboost (usually leave it at 1/2 bar when commuting), Turbo back exhaust, Pod and thats about it. No changes here for a couple of years.

Power FC won't lose it's tuning. Even if it does due to the 'heat', it is very minimal.

Ok, so it wont drift, but any way it could have been reset if the battery was disconnected or something like that?

paulr33 Grand Master

paulr33

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The ecu wont loose its tune or forget so its purely just how you are driving and possibly a bad batch of fuel

500 k;s to a tank is great so dont worry there. have a read of the powerfc faq (in my sig) it will cover most of your questions

JBird Contributor

JBird

Posted
Posted (edited)

Maybe you pressed a few buttons on the hand controller or somebody mucked around with it. This happened to a friend of mine.

If it is knocking, you can retard the timing using the hand controller - back it off a few degrees start at reducing it by 3 degrees until knock doesn't go above 20. This can be done in the mean time until you see your tuner...they should be able to sort it out for free if its a problem with PFC.

Also keep in mind, the RB knock sensor is pretty sensitive and may just be detecting other engine noise.

Edited by JBird
raps86 Rising Star

raps86

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hey bill i live in bathurst and have never seen ur car i thought the only 34s out here were mine and the yellow gtr. anyway wat servo do u use? i have similar mods besides i have the profec b spec2 and hks bov. the weird thing is that im getin beter fuel economy now that its warming up im geting about 400 2 a tank of fuel city driving. But out on the road it doesnt change even when my mum drove my car to orange as i had 2 take her car 2 sydney 2 pick family up and she isnt a lead foot and only got 14l/p100k.

Anyway it mite have block injectors witch mite b not giving it enough fuel under medium load but the ecu could b trying to corect by opening the injectors longer when not under medium load and running rich. it mite b worthwhile gettin the cat check for blockage.

Bill Collaborator

Bill

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The ecu wont loose its tune or forget so its purely just how you are driving
Vey easy, think less than 1/3 throttle
and possibly a bad batch of fuel
I had considered this, but its getting worse after several tanks from a couple of different servos.
500 k;s to a tank is great so dont worry there.
its not so much the k's its the sudden change
have a read of the powerfc faq (in my sig) it will cover most of your questions
Thanks, will do so.
Bill Collaborator

Bill

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Maybe you pressed a few buttons on the hand controller or somebody mucked around with it. This happened to a friend of mine.
The hand controller is attached and just sitting in the glovebox, so I spose the buttons could have been pressed by other stuff sitting on it.
If it is knocking, you can retard the timing using the hand controller - back it off a few degrees start at reducing it by 3 degrees until knock doesn't go above 20. This can be done in the mean time until you see your tuner...
Thanks, will do so.
Bill Collaborator

Bill

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hey bill i live in bathurst and have never seen ur car i thought the only 34s out here were mine and the yellow gtr.
Its hard to miss Carls :O .

Mine is a more sedate Silver.

Ive had the R34 for well over 5 years now (first one in town :O )

anyway wat servo do u use?
Either of the Shells on the highway (depends which way Im driving at the time)
Anyway it mite have block injectors witch mite b not giving it enough fuel under medium load but the ecu could b trying to corect by opening the injectors longer when not under medium load and running rich. it mite b worthwhile gettin the cat check for blockage.
Now theres a thought....

I think I might change the fuel filter and take the injectors downtown and have them cleaned.

Edited by Bill
raps86 Rising Star

raps86

Posted
Posted (edited)

ok yeah mines a silver 1 2. i only use the 1 on stuart st as its got all new tanks in it. i just changed the fuel filter in mine and i got more out of that tank with the same driving style. when u change the filter have a clean container and drain the filter out from the in side and give it a blow and check 2 see how dirty the fuel was that comes out of it. mine was lookin like tea

Edited by raps86
  • 1 month later...
Bill Collaborator

Bill

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Cleaned injectors, changed filter and ran a few tanks through it since then.

Fuel economy is better, but not back to what it was (About 1/2 way there)

Still got the knocking under load :rofl:

spark plug type and fuel filter type the same after service

I think you may be onto sonthing here.

How long should iridium plugs last before being replaced?

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