Rb25 Help

[krayzie32]

after driving around prett much stock since 2003 i got bored and i decided to mod the car a little...

started of with 32 gtr body parts, then big stereon system and then over the course of the last 6months, the list ended up looking like...

s2 rb25 with loom and ecu (hks 1.2mm metal head gasket installed)

s2 rb25 box

nismo coppermax clutch

nismo lightweight billet flywheel

1pc tailshaft

f-con s piggy back ecu (same specs as mine hence the ugraded ignition, intake, cam & fuel gear)

hks 264 in/ex cams

hks adjustable in/ex cam gears

splitfire coilpacks built in igniters

nismo 740cc injectors

rising rate fuel reg

hks gt2535 turbo

greddy profec b II boost controller

custom intake

z32 afm

jjr fmic

allow radiator

walbro 255l/hr pump

5zigen pro racer titanium exhaust

4in dump pipe

hi-flow cat

hicas lock bar

cusco adjustable front upper camber arms

cusco adjustable rear upper camber arms

cusco castor rods

hks hiper damper II coilovers

defi bf guages (boost, oil temp, water temp)

dba drilled and slotted discs front and rear

most of the stuff was put in some stage over the last 3-6months and the final step was ripping out the 20 n box and putting in the 25 n box, installing the fuel and ignition upgrades, wired it all up my self got everything (ecu, sensors, wipers, a/c, p/s, dash etc etc.. hks piggy back) running, turned key to find that car is really rough at idle...

car is running really rough at idle once warmend up and then goes crazy ie; 200-1400rpm erratic idling atalling eventually

also occasionally car is steady idling at 800rpm and then once i put a load on it like switch head lights on starts idling erractically again stalling eventually

or sometimes car is warm and and it just stalled i turn key then car stall immediately after.

when i take for test drive car pops and cracks and misfires, so im assuming it running lean, not like backfire when its rich...

but then when i apply brakes, the load of the brake lights causes the car to sort of stall...

i know ive done a heap to the car and have upset a lot of the electronics but i know that just a few tweaks need to be i.e. fuel map and boost map, but this whole idling issue is becoming a big nasty headache:

for those that might be able to help i have this information

getting 3bar on fuel guage with reds on (apparently between 3-5bar is good)

getting 2.1-2.4bar on fuel guage on idle (same as above but rising or boost pressure)

getting 12.8v at battery (car off)

gettign 14.2v at battery (car running)

getting 13.6v at battery (car running, lights and stereo and a/c on)

getting correct voltage at injectors

getting spark at coilpacks

checked all vacuum hoses for leaks

cleaned air flow meter

checked all gaskets/hoses/ic pipes for leaks

checked and cleaned aac valve and replaced gasket

havent checked fuel filter...

maybe not enough voltage to pump? as im getting 12.7v as opposed to the mod everybody does to get full 14v to pump for higher flow...

if i put fuel pump and return line back to front ie pressure goin through return and into fpr then into rail then rturn through filter back to tank will car still run??? really thinking this maybe cause as all of my fuel related parts are new

not sure how to check alternator but im sure the voltages speak for themselves,

not much more i can think of checking on but i hope this is enough information to get some answers,

if i have missed something please let me know and ill get that information too so you can help me chase this down...

really cant think of anything else other than i need a retune on my f-con but my tuner tom from bd4s said car should at least be able to idle fine...

for now any information will help thank you...

especially related to the fuel pressure issue which i think is the main culprit to my idle issues

thanks tim.

[blind_elk]

Voltages look ok. Fuel pressure seems a bit low at idle.

You CANNOT run the fuel lines back to front.

You are running HUGE cams and HUGE injectors - the car will have problems idling (ever heard a drag car or old-school race car idle smoothly?). Erratic idling can also be the AAC.

[paulr33]

why are you assuming its fuel? it could be a sensor? it could be a mechanical problem? it could be a mismatched part? it could be the tune?

run the stock ecu diag or check the HKS for any diagnostics

surely it would have some sort of sensor check section or basic engine sensors

check all the basic sensors first and then see if it gives you any diagnostics

has it been tuned or had any basic config etc? you cant expect a stock ecu to run big injectors and just work, so youll need to tell the HKS it has bigger injectors, and im sure some sort of base map

[krayzie32]

Voltages look ok. Fuel pressure seems a bit low at idle.

You CANNOT run the fuel lines back to front.

You are running HUGE cams and HUGE injectors - the car will have problems idling (ever heard a drag car or old-school race car idle smoothly?). Erratic idling can also be the AAC.

yeah I noticed the fuel pressures which is what bugged me... How do you suppose I increase it?

I didn't purposely install it back to front but it got me thinking if I accidentally mixed the lines up at the boot end causing the low pressure, if I clamp off return and it doesn't rise what does that mean?

Also I know that it's not gonna sound thensame at idle or idle as smooth as a stock car but still ibdont understand themassive fluctuation

[krayzie32]

why are you assuming its fuel? it could be a sensor? it could be a mechanical problem? it could be a mismatched part? it could be the tune?

run the stock ecu diag or check the HKS for any diagnostics

surely it would have some sort of sensor check section or basic engine sensors

check all the basic sensors first and then see if it gives you any diagnostics

has it been tuned or had any basic config etc? you cant expect a stock ecu to run big injectors and just work, so youll need to tell the HKS it has bigger injectors, and im sure some sort of base map

only sensor I could think of was o2 sensor so I disconnected and no diffence, mechanical or mismatched part?? Direction I could possibly look at?

I haven't had the rb25 ecu retuned for the gear...

But I was assured that the HKS fcon was running same size injectors, coilpacks, and same cams, I thounght that mabe a close enough base map to work off...

Can car be taken to the tuner as is?? Or is there a few more things I can look at before I send the car in...???

Again the fuel pressure is a big concern is there something I'm missing?

[Branelly]

I know you didnt mention an aftermarket bov, but i know they can cause retarded idling issues.

[krayzie32]

i have jdm greddy type with adaptor s in stock position plumbed back into intake pipe i guess it should be ok...

[krayzie32]

thanks to everone for their help but ive managed to resolve this issue myself.

with the help of the D.I.Y. section i completed the Fuel Relay Bypass mod to my Walbro intank pump and instantl notice alot more flow to the fuel reg,

i upped the idle static fuel press to 4bar and to cope with the 740cc injectors for now and no longer have any issues when lights and stereo etc come on.

along the way i changed fuel filter, cleaned afm, cleaned aac valve, triple check all hoses for leaks, recharged battery, added eathing kit, and it was finally sorted after adding direct feed to the pump via a relay.

thanks again.

[krayzie32]

now that the idle is sorted it off to the tuners to get the best out of my machine.