*searched* car dies when rpm's come down *VIDEOS*

[pacefarm]

need help....

been trying to figure this issue out for a week now, after the engine went back in.

here's my setup:

KA24de-T
stock bore arias 8.8 pistons
eagle rods
stock head
z32 mafs
t3/t04e
fmic
blitz bov
550 deatchwerks
walbro 255
z32 fuel filter
stock fuel rail and fpr
SAFCII
NGK BKR6e-11 plugs

before the re-build, car would idle just fine and ran without any stalling issues, aside from the decel-air problems caused by the blow off valve. those were solved by the SAFCII.

now, with the engine back in, i'm having problems starting the car, and keeping it running after the revs come down. with the 550's once i rev, the rpm's drop and the car dies, unless i keep them up with the accel pedal. once it floods, i gotta pull the fuse, crank it till it starts, shut it off, put the fuse back in and try again. let me say this again, the car ran FINE before w the same set-up. at lower rpm's, while driving the car sounds like a machine gun and hesitates. once i hear the turbo starting to spool (not building boost, staying out of boost for now), everything smooths out and its fine.

just to try things out, i switched back to the stock 270's and adjusted the fuel accordingly on the SAFCII. start-up is easier now, but the same "RPM drop and fall falt on its face" problem continues.

aside from the rpm's dropping, the car idles OK. vacuum reads -80 on the profec and .6 (x100 kPa) on the boost gauge.

i've cleaned the mafs and changed the plugs (bkr6e-11). dont know what to do next....

PLEASE SOMEBODY HELP!!!

http://i199.photobucket.com/albums/aa109/dsalni/th_MOV09276.jpg (http://s199.photobucket.com/albums/aa109/dsalni/?action=view&current=MOV09276.flv)
http://i199.photobucket.com/albums/aa109/dsalni/th_MOV09275.jpg (http://s199.photobucket.com/albums/aa109/dsalni/?action=view&current=MOV09275.flv)

[pr0ject TRUENO]

What setup is your BOV? Open atmosphere or recirculating setup? That could be your problem.

[pacefarm]

What setup is your BOV? Open atmosphere or recirculating setup? That could be your problem.

the bov is atmospheric. thats not the concern tho, since it ran just fine before, with the same setup. the car dies even when the bov doest come into play... even if it did, the decel air settings are there to compensate for the stall problem caused by the bov.

[NI_YON_Zenki]

sounds like you are working with some boost control issues, but check your fuel filter as well?

[pr0ject TRUENO]

Hmmm no compression problems huh? Sounds weird that you're having the same stumbling problems with the 550 and the 270 injectors. What are your supporting fuel mods besides SAFC? FPR? Rising rate?

[pacefarm]

Hmmm no compression problems huh? Sounds weird that you're having the same stumbling problems with the 550 and the 270 injectors. What are your supporting fuel mods besides SAFC? FPR? Rising rate?

yeah it is weird.. compression is amazingly perfect through-out all 4 cylinders.
the thing that is confusing is that prior to the re-build, the setup was identical to what i have now. as for fuel mods, SAFC is the only thing i'm running right now, aside from the bigger injectors and the walbro.

the fuel filter has less than 100 miles on it. if i were to clean it, what would be the best way?

[pr0ject TRUENO]

Don't clean it. You'll damage the filter element. Might as well upgrade to a 300ZX turbo one. Costs less than $30 from the dealership or Performance Nissan. If it has less than 100 miles on it, chances are it's still good.

How did you tune the car? Sounds like before boost kicks in it's dumping too much fuel, maybe causing the idle problem. Other than that I'm stumped.

[Mlogue84]

Now i don't know to much about this setup at all but i do know when i had rev problems (with the car dying without my foot on the accelerator) i had to adjust my throttle position sensor.. as for my hesitaion i had to change out my fuel filter. i too have a walbro 255 with the stock fpr... some people say that you have to change that out but i don't know how true that is... once again it's still all a little new to me.

[pacefarm]

Now i don't know to much about this setup at all but i do know when i had rev problems (with the car dying without my foot on the accelerator) i had to adjust my throttle position sensor.. as for my hesitaion i had to change out my fuel filter. i too have a walbro 255 with the stock fpr... some people say that you have to change that out but i don't know how true that is... once again it's still all a little new to me.

how would you adjust the TPS?

i dont know if this is part of the same problem or not, but when i try to set timing and unplug the TPS, the wont idle AT ALL; gotta constantly keep my foot on the accel pedal. could this be related???

[Mlogue84]

well i don't know exactly how it is done because my friend who's a mechanic did it. i'll find out right now...

[Mlogue84]

go here...
http://www.240sx.org/faq/articles/throttle_position_sensor_adjustm.htm

[pacefarm]

go here...
http://www.240sx.org/faq/articles/throttle_position_sensor_adjustm.htm

thanks man..

gonna go mess with it some more..

[Mlogue84]

let me know how it goes...
Good Luck, Mark

[pacefarm]

swapped back to the 550 cc's and now it floods almost every other time i try to start it. once it starts up (IF it starts up), the rpm's dont hold and just drop even worse than with the stock injectors.

bad FPR???

[pr0ject TRUENO]

Stock FPR?

msglength

[pacefarm]

Stock FPR?

msglength

yes. never gave me any problems in the past.

[idrum2loud]

MOVE YOUR MAF FARTHER AWAY FROM YOUR TURBO AND CHECK FUEL PRESSURE.

My car was doing the same shit, and i moved my MAF farther away from the turbo ( the turbulnece from the turbo will make iot read false ) that and my fuel pressure was off. Check and do both.

[pacefarm]

MOVE YOUR MAF FARTHER AWAY FROM YOUR TURBO AND CHECK FUEL PRESSURE.

My car was doing the same shit, and i moved my MAF farther away from the turbo ( the turbulnece from the turbo will make iot read false ) that and my fuel pressure was off. Check and do both.

installed a fuel pressure gauge and an adjustable fpr. fuel pressure is good and stable, unfortunately the problem is still there. i'll move the mafs further just to eliminate the posibility of that being the problem, but the car was just fine w the same mafs to turbo length before the rebuild..

also changed the injector o-rings..

is there any way to check that mafs itself if its going bad?

[drift into a curb]

Hey dsalni, i'm getting the same problem of the stumbling than stalling. Have you tried the TPS? That's about the last thing I want to do since my TPS was running fine before the turbo, but let me know if you solved your problem at all.