top end power problem..

[Anonymous]

fark these cars definatly test your stress levels...
well was having trouble with the car not wanting to pull much in above 5500rpm, so i got it on the dyno.
-fuel had gone from being just a little rich(last year) to now being off the dyno scale as it could only read 10:1.
-so they checked for boost leak as it wasnt boosting right.
-found a bolt missing that holds the throttlebody to the engine.(car went better but not totaly fixed when they put a bolt in there.
(they have presurised every thing to try and find a leak)

They have tested the afm the compter, and all other electronic things.
the timming is spot on, and theres no fault codes comming up what so ever.

so now u can get 3 good pulls out on the road before the power goes dowm,(but it still boosts to 14 psi and stays there when the power goes down.still no fault codes.

on the dyno they had a scanner on the ecu and someone with a multi checker thing on the afm, and well at 5500 for a split second the scanner picked up that the ecu went into open loop or somthing, but the afm was reading fine on the multi meter.
(before christmas they found the cam chain out a link so they put it back to the right spot, but now they are thinking maybee it has other spec cams in it)
so they said next step is to pull the cam cover off and check the cams with some tool i dunno the name to see if they are standard, and then check valve springs, throttle body, turbo and well im guessing the list goes on.
ANYONE GOT ANY IDEA WHAT IT COULD BE AND IF SOMEONE IN JAPAN HAS CHANGED THE STUFF IN THE ENGINE, COULD THERE BE A REASON THAT THEY WOULD PUT THE CAM CHAIN OUT A LINK??? AND IF SO AM I GOING TO CAUSE ANY DAMAGE DRIVING IT.
engine runs smoothly on idle not rattly,but if u stand at the back of the car near the goose, it sounds rough like theres an air leak or somthing, the sorts sound realy airy now (wasnt like that when the cam chain was out a tooth)

sorry for such a long post just pissed that the problem cant be found.
made 154kw atw before christmas now in 20kw atw down on that figure..
thanks luke...... (help please)....

 

[zia]

how is the boost being controlled do you have bleed valve fitted. or does the ecu have chip/or board fitted. have they checked lambda sensor if it is switching? does it have big injestor/up graded pump/fpr?

zia

 

[Anonymous]

hey mate, have just got a turbo smart bleed valve.total standard ecu.
not sure about the pump but am sure that it would have to be a bigger one to flow that much fuel that it is at 1 bar boost, and the injectors are the standard colour but could well be highflowed.
TOOK IT FOR A RUN TODAY,(THEY HAVE TURNED THE BOOST DOWN ABIT I NOTICED.)SO WHEN THE OIL TEMP IS BELOW 90c AND U BOOT IT THE BOOST NEEDLE JUST GETS PAST THE 7 ON THE GAUGE,AND IT PULLS CLEANLY TO 7500RPM, BUT IF THE OIL TEMP IS ABOVE 90C THEN THE BOOST NEDDLE GOES ONLY TO THE SEVEN MARK, AND IT FEELS LIKE YOUR LOOSING POWER AT ANYTHING OVER 6000RPM.
im thinking its going into some sort of safe mode, but the mechanic said no cant be, as its boosting fine and timmings fine and it ant deting or pinging and there isnt any fault codes showing..
IS THERE MORE THEN JUST ONE SAFE MODE, IE:LIKE ONE THAT STILL BOOSTS FINE BUT JUST CHUCKS A HEAP OF FUEL IN???
only got 60klm, to half a tank of fuel on highway driving, sitting on 100klm/h thats realy realy bad....
am getting pissed with it now, as its been 9months since ive had a smooth running r.......

 

[j10gtr]

It could be the crank angle sensor playing up and altering the timing this tends to happen when the car is hot.

Also have you checked for knock maybe after a couple of runs when the engine is hot the ecu is picking up some knock. If knock is detected it will retard the ignition timing and the car will feel flat.


Thanks
Paul

 

[Anonymous]

apparently the timming is spot on and theres no knock or detting when the problem aross on the dyno, just massive amounts of fuel being pumped in.
have just read about 20 old topics,on this problem but every thing anyone has tried or done that has fixed the problem has been done on my r but did nothing...

 

[Fast Guy]

What intercooler do you have fitted?
It sounds like you might be suffering from heat soak/build up as you're getting less boost when hot. Abit like the hot day/cold day scenario.
If your gauge was going past the 7 before that could be over 1bar boost. (the std gauge ain't known for it's accuracy) If it's dropping a couple of psi boost that could be 20bhp maybe and you'd notice that loss.

You realy need to find out why it's running so rich and sort it. If it's far too rich, you could be damaging your engine with bore wash, where excess fuel washes the oil off the cylinder walls and promotes wear through lack of lubrication. At the least it could just be robbing you of power and money through wasted fuel.

I take it they've checked the MAF grounding, injectors (off car for flow and pattern), fuel pressure, fuel regulator working, coolant sensor, lambda sensor. That's just some ideas.

 

[Fast Guy]

The standard power curve starts to drop off at around 6200(ish)rpm. If yours is going before that , it could be your cam timing after they changed it or your turbo might just not be upto it.

 

[zia]

what is the exact feul pressure? if it running to rich you could ask them to increase boost so the a/f ratio is more 13:1 etc and double check lambda sensor is switching is it ,or maybe giving weaker/incorrect voltage to ecu which in turn is increase injector pulse.also check top mount for blockage. also what is the air temp in/around the engine there is konw problem that alot heat soak on the intercooler will kill power once air temp reach certain level.

zia

 

[Anonymous]

thanks for the replys.
zia, not sure what the fuel pressure is at, or the temps, all i can say that the temps outside are around 29deg, so not hot at all, considering it used to still go hard on a 40deg day..
spoke to him yesterday, to confirm all things they have checked, and that is basicly everything u all have mentioned, except checing the flow pattern of the injecters.
(lambda sesor only effects it at ide he says)
but what do u mean by is the lambda sensor turnning off????

dont realy wanna run more then a bar boost, to cover a problem up, as the car never used to run this rich,

i think that if i fit an oil cooler to keep oil temps under 90deg then i will be fine, cause i have no problems then...
IF U GO INTO SAFE MODE, WILL THAT SHOW UP ON A FAULT CODE CHECK??????
luke....

 

[c20ona]

i'm having the exact same problem !, and it's doing my head in too mate.
it ran fine up until i fitted a norris front mount, greddy profect b and uprated fuel pump.took it to a dyno and after 5500 the car over fuels like a bas and the boost disappears.got 245bhp at 1 bar !!!!!!!.but as mentioned before, the car runs spot on low range etc.should i maybe get the ecu upgraded as well to comp for these changes ?.
also, would the restrictor thingy (small bullet type thing in the top pressure pipe) cause any issues.i've taken it out and even put it back but makes no difference.hope someone can figure this out cos i've been lost for months ?.

cheers

kenny (i'm new to the site by the way but been an 'r' owner for over 4 years now.great little car...well, until recently)

 

[c20ona]

sorry, got a hks fuel computer as well.turned it down but it's still rubbish top end. :?

 

[Fast Guy]

If you go into fail safe mode (the car won't rev above 2400rpm) the ecu check should give you a code as to what's put it in that mode.

If the det sonsor kicks in, it should pull back on the ignition timing and boost, but will reset when you turn the ignition off. (although I can't actually find this in the manual )

The restictor thingy in the pipe from the plenum is there to increase boost, without it you shouldn't make the same boost level.

If boost disappears above 5500rpm, your turbo might not be upto it or it could be ignition or cam timing out maybe.

 

[c20ona]

ah right.so even with a boost controller i still need the restrictor.better pop it back in then.
but i'll have the timing and turbo checked to see if this is my prob.
can't knock it, had the car for over 4 years now and never had to spend
a penny ! (apart from the reg service of course).

thanks again though

kenny

P.S - Anyone know how i get my pics onto the owners page ?.
Went to the e-mail section where your details etc go but it says
theres a problem with the address ?

 

[zia]

if the problem is temp related have they checked the coolant temp sensor if it giving correct resistance when hot and cold? you really need to know all stuff i,ve stated to able to give idea what is happening if they don,t know what fuel pressure it is what how will you know it is,nt regulator that is faulty? also lambda sensor should switch from closed loop to open loop.and make sure there no leaks at turbo, dumepipe, as this will give incorrect oxygen content to lambda sensor

zia