Ok guys need help on this one

[joeytvr]

I have a 1990 7mgte supra. mods below.

This is the problem, car pulls hard until around 5200rpm then falls off. I have tried everything but bolting on a kitchen sink... lol

fuel pressure is 38psi at idle and raises to 59 psi under 16psi of boost.

My latest thoughts, one of the pumps taking a shit, plugs getting blown out (.024 ) gap. well thats about all i have left. Today i thought maybe pull the airfilter off. short cheap metal filter from autozone. lol

Funny thing is sometimes it runs great. Some days if i add about 9% fuel it hauls ass, next day or later i will need to pull the fuel back out. even then power still tappers off in higher rpms. ?

Been about a year of playing with this, i drive the car daily now and it is driving me crazy. I have another race with a built cobra and do not wanna gamble on how the car is gonna run. Help please?

Mods

Tein suspension
brembo rotors
rims
nitto tires rear drags
feramic clutch disk
short shifter
fluidyne radiator
electric fans
aftermarket front mount intercooler
all custom intercooler plumbing
balnaced crank
stage 3 reworked rods
JE pistons
total seal rings
greedy head gasket
full port and polishes cnc head
1mm oversized valves
high lift vavle springs
titanium retainers
custom regrind cams (do not know specs)
550cc injectors
dual 255lph intank pumps
dual feed fuel rail
aeromotive billet fuel pressure regulator
MAF pro computer Speed density conversion
4" turbo intake with custom race ram air
sp67 turbo
HKS cast manifold (rare)
tial 44mm wastegate
billet blow off valve
NX nitrous kit

 

[str8_6]

does your boost drop too or does it hold steady, but power band still goes down?

 

[joeytvr]

boost holds rock steady at 16psi and fuel pressure itself holds steady?

 

[joeytvr]

turbo has no play, not a drop of oil on intake or intercooler side. i know thats not it. pressure tested intercooler system up to 35psi

 

[jdub]

ECU codes?

 

[joeytvr]

no codes, other than power falling off after 5000rpm she runs like a champ. pulls super hard then just runs out of steam//,,,

 

[joeytvr]

just to make it clear it does not miss or sputter just a smooth decline in power. What about bad grounds? I think a motor ground may be missing

 

[dumbo]

you said no codes..did you intall the resistors needed to fix the codes with maft w/speed density??

i got the same problem. but mine was right away..nowhere near a year of runnin


so has yours just devolped? or been since the start?

what are your settings, d you have ptt or WOT enabled??
do you afr go rich in the top?

 

[HKS_TRD]

Detonation or knock control system being engaged?

 

[joeytvr]

you said no codes..did you intall the resistors needed to fix the codes with maft w/speed density??

i got the same problem. but mine was right away..nowhere near a year of runnin


so has yours just devolped? or been since the start?

what are your settings, d you have ptt or WOT enabled??
do you afr go rich in the top?

i say yes on resisitors but ya know at this point i may chaeck....lol

has been this way from the start just more noticeable once i started to turn up the boost. i did all the settings in the maf over a year ago so ptt and wot i have no idea.

what plugs should i be running? i have autolite 3923's in it

 

[joeytvr]

Detonation or knock control system being engaged?

i thought maybe same thing at first

 

[Suprafast0422]

If it varies day by day id check any sensors that measure temp or that air temp/humidity would have any effect on. Too much for a piggyback maybe? Time for a standalone?

 

[joeytvr]

forgot a important thing, the car missis and pops out the exhuast at idle. No noticeable missfire off idle.

 

[jdub]

Likely due to the plugs...the AutoLites are 1/8" shorter than the JIC std plugs the 7M uses and can cause arcing between the wires/plug tip. Get NGK coppers...BCPR6ES is the stock heat range plug. You may want to go 1 step colder with BCPR7ES.

 

[adampecush]

Is there any chance you are exceeding the capacity of the 550cc injectors?(or putting them into a static state above 5k)

 

[suprahero]

Is there any chance you are exceeding the capacity of the 550cc injectors?(or putting them into a static state above 5k)

I wouldn't think he's exceeding the injectors on 16psi.

Have you had it dyno'd and saw the horsepower falling off or just feeling it with your britches?

 

[dumbo]

AFR??? Also have you had it dynoed^^

 

[adampecush]

I wouldn't think he's exceeding the injectors on 16psi.

Have you had it dyno'd and saw the horsepower falling off or just feeling it with your britches?

yeah, I wasn't that sure of it...just thought I'd throw the suggestion out there. What kind of power are you pushing at 16 psi?

 

[joeytvr]

yeah, I wasn't that sure of it...just thought I'd throw the suggestion out there. What kind of power are you pushing at 16 psi?

never dynoed. Car has run 11.60 as it is. traps 121

ordered some ngk 3330's cold enough?

 

[jdub]

ordered some ngk 3330's cold enough?

Those are NGK BCPR7ES...yes, should do the trick. Gap at 0.028".