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NismoR34
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279 Posts
Discussion Starter · #1 ·
Guys, i been getting this problem lately, fixed a big boost leak and car pulls good but under full throttle, it feels as if its holding back a bit.....HOWEVER if i throttle the pedal, lets say hold it at somewhere in between 1/4 and 1/2 throttle, it pulls as if its normal, boosts good etc.

Any throttle however, i read 15.7-16.1 on idle on wideband and under full throttle or 1/2 or 1/4 the wideband just reads 10.5 etc, very rich. And my fuel pressure is 38psi idle and goes up to nearly 60psi under boost/full throttle etc.

I went on the dyno to see what throttle i will get max and its only at 1/4 to 1/2 throttle im getting best power results.

Full throttle 9psi - 318RWHP

Full throttle 14psi - 327RWHP

In between 1/4 and 1/2 throttle - 348RWHP

I mean, for a neo 25 on stock ecu/airflow/injectors, thats not bad, but the hold back under full throttle is killing me.

I have the following mods:
NEO RB25DET
Mishimoto Intercooler
2.5" Piping from Turbo side to intercooler
3" piping from intercooler to throttle body
Q45 Throttle body
Greddy intake manifold
T61 Turbo
X02 Extractor Manifold
44mm Wastegate
Full 3.25" Exhaust ( 3" total diameter internally)
Walbro Intank Fuel Pump
Nismo Twin Disc Clutch
HKS Fuel Rail
Stock Injectors
Stock ECU
Stock Airflow
HKS Spark Plugs
Aeromotive Fuel Pressure Regulator Set at 38psi idle

Thats about it!

Anyone think fuel pump might be an issue? How the car has been parked up for a year and a half? I dunno, but the fuel pressure goes up to nearly 60 under boost.

I get NO MISSFIRE AT ALL
 
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2,006 Posts
t61 0n standard afm and injectors and with a little walbro tank is overkill! get some injectors a z32 and a bigger pump! and as martin says standard ecu! wtf has it been mapped at all? it sounds like an accident waiting to happen! what boost controller you got? as it aint on your list?
 

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Registered
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468 Posts
i have the same problem with the following current mods

Japspeed Cat back,
Japspeed Backbox
Japspeed silenced decat
Japspeed D1 FMIC
Hks downpipe
Blitz Bov
Apexi power airflow intake
Apexi AVCR gen2 boost controller
Bosch Fuel pump
Uprated iridium spark plugs (7*)
RSP 400+ Hybrid turbo (steel internals)
Uprated actuator

i think its all down to me needing a remap my standard ECU has never been touched, my car goes through petrol faster than usual. as you can see upgrading everything apart from the ECU is a big problem! my nisune arrived this morning so that will help once in. my first feeling was my standard coils or i was maybe maxing out afm or injectors?

im hoping a nice map will iron things out for me............. might be something for you to consider?
 

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Car work on a budget, a very SMALL budget :(
Joined
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3,080 Posts
Do you think I have enough mods to make the stage 1 ECU from RSP work out?

Apexi Induction Cone
Iridium 7's
R34 GTT SMIC
Greddy Profec B S II EBC
5Zigen Cat Back

Im sure I am missing something...
 

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NismoR34
Joined
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279 Posts
Discussion Starter · #9 ·
Using as turbo xs manual boost controller. Wwastegate stock spring is 10psi, raised it to 14.

I was figuring today it could be the cause of stock injectors/ecu/airflow bcuz the first gear on full throttle goes all out, but 2nd or any other gear on full just does the problem, unless i let off half throttle....probably lesser air going in lol

I had a microtech to put on but a jackass electrician disappeared from the place with it and other peoples stuff.

All i had for my other car was an aem fic, so i might as well just drop that in until money comes along for a full standalone again for the r34
 

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Registered
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468 Posts
gaz i tink ur missin FMIC? i believe they do indeed do a generic chip for those mods,double chek wit em dough or pay the extra n gt nistune fit locally instead.im north west also. dnt tink u can beat a custom map. Leon thats exactly what mine does 1st gear aswell, ill let u knw how the map goes in due coarse.
 

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1,110 Posts
Neo differs from std rb25det in that it richens up and retards the ignition when it sees the max 5volts at the afm. It feels a bit like a little "burp" from the exhaust and isn't very harsh. You will easily reach 5 volts ith FMIC and uprated turbo.

There is a proper boost cut sensed from the boost sensor on the top rear of the engine, when you hit 1 bar its cuts the engine and you will feel like you are gonna be thrown into the windscreen, its very harsh. The neo ecu also alters the map using the same boost sensor signals, something which a std rb25det DOESN'T do because the boost sensor on those engine is simply to drive the boost guage. The neo engine has a SEPERATE boost sensor that is just for the gauge located on the drivers side.

Good coilpacks are a must and standard ones are fine if in good order. I have new genuine Nissan coilpacks on mine and it runs just under a bar (0.98) fine as far as ignition goes. As soon as I can afford I will going Nistune to get the boost cut raised and eventually Z32 and bigger injectors.

So in case you missed that, neo ecu is different to std RB25det because it has a dedicated boost sensor for the ecu that affects the map and has a true boost cut. The std rb 25 doesnt have a boost sensor signal to the ecu, it uses the AFM only.
 

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Cambridgeshire
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1,604 Posts
Using as turbo xs manual boost controller. Wwastegate stock spring is 10psi, raised it to 14.

I was figuring today it could be the cause of stock injectors/ecu/airflow bcuz the first gear on full throttle goes all out, but 2nd or any other gear on full just does the problem, unless i let off half throttle....probably lesser air going in lol

I had a microtech to put on but a jackass electrician disappeared from the place with it and other peoples stuff.

All i had for my other car was an aem fic, so i might as well just drop that in until money comes along for a full standalone again for the r34

the turbo and set up you have is much beyond the scope of the electronic support you have on the car..
 

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NismoR34
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279 Posts
Discussion Starter · #13 ·
Getting the AEM FIC Installed tommorow, evening time will collect and start some tuning.

I wanted to find out, my boost sensor that uses the vacum hose, the connection on it broke, as its plastic and i dunno if thats gonna affect anything....

Anyone?
 

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NismoR34
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279 Posts
Discussion Starter · #15 ·
Not that one, the one on the firewall.

Will be collecting car today hopefully, they was having some issues with the CAS wiring on the NEO 25, so if anyone knows what to do, lemme no, incase they dont get through with it
 

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468 Posts
i still run the standard boost gauge in my car and a boost controller. if you say ur little connector for the boost gauge is damaged and not working the engine warning light should be on as that is what comes on when i disconnect mine. ive had a fiddle in the past i wanted to run both gauge and controller that was my aim. if i remember correctly dean advised me, we got around the boost cut also...... which was a pain but got there in the end.

The way i got over this is to simply plumb the boost controller boost sensor into the existing 8mm black vaccume pipe from engine to standard boost sensor (the one with the vaccum filter on). i used a t-piece for this, as originally i had it run direct. it seemed to do the trick no enegine management lights and no boost cut at 1bar. ive now got a hybrid which sucks more air and not expecienced it yet.

i was also told by dean that when my piggyback goes on this will override the boost cut.

hope all that is of some use. if the connectors broke im sure you could replace it or tape it. if the engine management lights not on it should be fine so i wouldnt worry.
 

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NismoR34
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279 Posts
Discussion Starter · #17 ·
Got the AEM wired in and tuned.

Apparently the car was leaning out and i need more fuel. I maxed out the injectors on 11psi with this turbo. Oh wells.

As i said, i did 348 at 14psi with half throttle before the aem and now at 11psi tuned on the aem, the car is feeling faster and it goes through ALL GEARS WITH NO HOLDBACKS, just FULL THROTTLE ALL THE WAY INSANE POWER!

What size injectors is ideal for 18-20psi? i was thinking either some 650-750cc's
 
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