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R33 11psi Flat Spot In Rev Range Fmic-pod-exhaust-turbotech Boost Tap

SS#eater

By SS#eater,
in Engines & Forced Induction

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SS#eater

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Posted (edited)

i have r33 gtst running 11psi with just jap front mount 600x300x76, k&n pod clod air exhaust..etc.

when you floor the acelarator if seems to have a flat spot around 4-5000 rpm then picks up again, feels like its holding back ...but if you let it rev out without flooring it its not to bad...sometimes it revs out smooth ...running 9 psi it feels like it pulls harder and revs smoother.. should i change plugs or the gap...coil packs...

any help... :happy: could it be leaning out...

Edited by SS#eater
Links Veteran

Links

Posted
Posted (edited)

I would have to take a stab @ R&R is kicking in.. what's happening is that it's ramping up the boost.. detecting the increased air flow.. than dumping in fuel and retarding the timing..e.g. rich & retard - protection system is kicking in to prevent over boosting..

By slowly easing it in - you won't experience this as it won't see a huge spike of air flow..

I would suggest lowering the boost.. or just not slamming the foot down in 1st and 2nd..

OR - get a power fc and tune it..

edit - It won't be leaning out.. if it's using the stock ecu this is a protection system.. and will be riching up the mixture instead..

Do a bit of a search. you'll find plenty of topics..

Edited by Links
_8OO5TED_ Mentor

_8OO5TED_

Posted
Posted

Rich & Retard it is, I have exactly the same mods making about 0.8bar and the same thing happens with freshly gapped Iridium plugs. I have a Power FC which is about to be tuned, should solve all the problems. Alternatively a cheaper solution would be a SAFC II.

Angry Proficient

Angry

Posted
Posted (edited)

can i ask why your gapping Iridium plugs though?

anyways.. if your not runing iridiums in yours SS#eater.. invest in another set ..with a 0.8 gap ... coppers.

its fairly typical of a 33 to have the flat spot... only way to tuen it out is the above mentioend SAFC or PFC.....

oh and is your K&N filter the oiled type? i dont thnk that woould be giving your AFM much to work with coating the sensor with oil.

Edited by Angry
SS#eater Collaborator

SS#eater

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can i ask why your gapping Iridium plugs though?

anyways.. if your not runing iridiums in yours SS#eater.. invest in another set ..with a 0.8 gap ... coppers.

its fairly typical of a 33 to have the flat spot... only way to tuen it out is the above mentioend SAFC or PFC.....

oh and is your K&N filter the oiled type? i dont thnk that woould be giving your AFM much to work with coating the sensor with oil.

yeah it is an oil type..it will be gone today!....iridum plugs and power fc...there goes my bank account..lol

thanks for the help let you know how it goes...

mad082 Grand Master

mad082

Posted
Posted

sorry to butt in, but it isn't rich and retard mapping. it is to do with the cams. you will find that cars that are stock will do it (i mean completely stock, exhaust and all). a pfc won't fix it at all. there is a thread on here where people were trying to shift the cam change point to get rid of it but it didn't really make a difference.

Munna1 Proficient

Munna1

Posted
Posted

I will put money on it been rich and retard. Regap your plugs to 0.8 if that doesnt work get a power FC or a SAFC. My car used to do the same thing even when stock the more mods I did the worse it got. SAFC fixed the problem for me.

cheers

mad082 Grand Master

mad082

Posted
Posted

it can't be rich and reatrd if it does it when stock. why would nissan a protection in that happens when the motor is stock?

it is the hydraulic cams changing back. the switch at 1500rpm, then back at 4500rpm. there is a thread on here that explains it. had a quick look but couldn't find it, will look again later.

rich and retard is a sudden loss of power. it is a violent stop/start, not a slow point of acceleration.

LatinR33 Experienced

LatinR33

Posted
Posted

Drop boost to 10 psi, get a safc from the for sale section and ur sweet. if the car runs good on 9psi but crap on 11psi then meet half way and get the fuel mixtures tuned :starwars: have a nice day.

Links Veteran

Links

Posted
Posted
it can't be rich and reatrd if it does it when stock. why would nissan a protection in that happens when the motor is stock?

it is the hydraulic cams changing back. the switch at 1500rpm, then back at 4500rpm. there is a thread on here that explains it. had a quick look but couldn't find it, will look again later.

rich and retard is a sudden loss of power. it is a violent stop/start, not a slow point of acceleration.

I don't believe that this is what is happening.. Mine does it depending on how quickly my boost ramps up.. doesn't matter what RPM.. ease it in.. and it's fine.. flatten it.. it spikes.. and I get a slight dip than it comes back up..

Could be spark plugs getting blown out..

It's a stock motor - running 3PSI than the maximum all the way through the rev range.. that's what will do it.. say your spooling by 3,000rpm.. that's 5 or 6PSI (Double) what the ecu would be expecting to see.. that would explain why it R&R's..

HOWEVER there may be something else going on.. but I don't believe that it's the cams changing.. as I get smooth power all the way through the rev range in 3rd or 4th gear when easing it on.. even in 2nd.. Oh and my cars very stock except for the bleed valve

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