Frankiman's street/track GTR project

[GTR-Dad]

the final specs are simply impressive;

a perfect cross weight distribution of 50/50 was acheived with AND without driver

Hmmmm.... Are you sure? Whenever I get into my own car it gets heavier on the side I'm sitting on. I've been considering a Maclaren F1 to avoid this, but... jking.

Seriously, how can you reconcile adding weight to one side, but both sides get heavier by the same amount?

Dan

[jessem]

Its CROSS weight man, not side to side weight

[archaeic_bloke]

Hmmmm.... Are you sure? Whenever I get into my own car it gets heavier on the side I'm sitting on. I've been considering a Maclaren F1 to avoid this, but... jking.

Seriously, how can you reconcile adding weight to one side, but both sides get heavier by the same amount?

Dan

its because of the suspension, the suspension purpose is to exactly distribute the weight of the car equally over all 4 tires...

all this means is when frank plops down in his car, his suspension is now set up properly.

[frankiman]

without a driver, side to side weight is 50/50, with driver its probly 52/48

but with cross weight, whenever you add/remove weight on the longitudinal and/or perpendicular axis (determined by the center of gravity viewed from above) it doesn't change the cross weight at all

ex;
you could put a 400lbs block of led directly in the middle of the trunk and it wouldn't change the cross weight a bit

[GTR-Dad]

without a driver, side to side weight is 50/50, with driver its probly 52/48

but with cross weight, whenever you add/remove weight on the longitudinal and/or perpendicular axis (determined by the center of gravity viewed from above) it doesn't change the cross weight at all

Thx. I was reading 'cross weight' as 'side to side'.

Should be a great handling car!

Dan

[frankiman]

so, as some of you may have read in another section, i was part of the UltraRide this weekend with 6 other GTRC members

but for some reason my engine was running super crappy, and i couldn't keep my speed steady because the car would studder / misfire / backfire everytime i would put the slightest pressure on the throttle

but as soon as i was into boost, no problemo

apparently, i was making ALOT of backfires,
Mitch32 even caught some on video


so tonight, i wanted to see for myself, and went out for a drive on the highway, and positionned my GoPro HD camera on the rear bumper in 60 frame per second mode to catch any occurence

well....

this is the kinda of misfire / backfire i get all the time when applying very little pressure to the throttle,;



but the other night, i ajusted my TPS, since then my car as been running super rich (based on my AEM wideband)
and when i left off the throttle to slow down under compression, instead of going full lean like before, now it stays really rich (12 afr) for a couple seconds (5-6) before going full lean

so this is what i got tonight, in just 15 minutes of driving;

enjoy the fireworks;








anyone has any idea what could be causing this

oh and also, when i ajusted the TPS, my idle as gone down to ~500rpm ish and i pretty rough, but still idles at 12afr
tried to ajust the AAC valve and throttle cable tension, but couldn't find the right comination

[bellis_GTR]

That is F*ckin sick!! Sorry I dont know your problem lol Amazing shots!

[nelsonmxmarc]

TPS voltage value is calculated how? Via consult or a multi meter? You should be around ~.48/.50 on a fully closed circuit (idle). Misfires could also be due to plug gap or failing coil packs. I think i heard your coil packs were kind of on the edge, no? If that's the case, you're misfiring, building up fuel and burning it off on the next cycle.. Would cause excess fuel to burn off in this manner.. And yes, your car is running effing weird.. I was behind you sunday and even cruising at a steady speed you were spewing black smoke and popping like crazy..

[frankiman]

well, ive only adjusted the TPS angle, haven't checked the voltage, i'm spending the whole afternoon at Almasi for a re-tune, i'll have robin check everything...

it couldn't the plug gap, since i've gapped it a bit less than last year (for more boost), but my problem always occurs with very little load under 5 psi of boost

and the coilpacks and brand new Spiltfire, even tested them on Mitch's car and they were fine, Tyler has had my old coilpack for months now, could i have them back?

[nelsonmxmarc]

I think Mitch has them now. lol
Those things have been around

Hmm... sounds like air - boost leak perhaps. TPS voltage is tuned in precise increments, however. Even being slight off a tenth of a volt is enough to trigger small issues. I had mine adjust for .45 when i purchased the car, having it reset to .49 made a world of difference.

Tyler has consult, its an easier way to deal with it. But like you said, Robin will probably be able to get it all done no problem. Hopefuly you'll pinpoint the issue.

[nelsonmxmarc]

Oh one quick mention, i think when adjusting the TPS, the AACV will likely override idle adjustment. I dont recall off the top of my head but messing with the TPS shouldn't change idle values? If that's the case, unplug your TPS (not remove), then change the idle via the AACV FIRST, then readjust the TPS to match. Idle should be around 950 or so. TPS unplugged, idle will not fluctuate with the AACV properly adjusted.

[archaeic_bloke]

awesome photos, unfortunate situation.

my 2 guesses:

1) like marc said, it would make sense if its a vacuum leak, that would also explain your 3 PSI drop on those dyno sheets... can you pressurize your charge piping and vacuum lines accordingly and come up with a test to determine if its all as it should be? or start to think about other systems, maybe one or 2 of your injectors are leaky... try to look and see if theres any leaks around the injector o ring seals,
bottom line is you're getting too much gas while off boost.... while on boost you're fine because all the extra gas can be consumed during boost with out issue.

to summarize this point: a) its a fueling problem... OR b) its a vacuum leak problem.

2) could also be O2 sensors... i know i've going on and on about O2 sensors but dude, what you're describing was exactly my situation when i had one O2 sensor blown out... if one or both of your O2's are done, it would also do the things you describe. testing O2 sensor's is kind of difficult for me, i don't know how to do it.

options: a) ask tyler to borrow is consult cable and scan ur system and see what the car is telling you... B) you tried to pull any ECU codes yet?

gotta get her ready for friday~!

[RWD_GTR]

my guess is because you just got a/m bovs you no longer have the recirculation pipe. mine ran like **** when my bovs were vented to atmosphere. doing this makes the car run rich at idle and partial throttle. i fixed it by turning up the idle screw and adding more oxygen to the mix.

[aN4rk1]

Francois, off-topic question:
Where did you get that string of LEDS under your boot lid in the last pic? thanks

[archaeic_bloke]

hey yajh!! wtf man!? i never seen this before on any other skyline even!!
also, i run atmo BOV's... at idle it should make no difference at all if installed correctly, only difference comes when they're in use obviously, when you shift you'll notice backfires due to excess fuel in mix, i think his BOV's set up is unrelated to this problem.

hey man give us the 411 on this photo below!!!