MaDMaX024

I went to the dyno yesterday and as i was watching the motor on every single pull, at just about 5000rpm the motor started shaking like it was misfiring however the power delivery is still smooth and the shaking is not noticable in the car whatsoever..is this normal or is there something i should check?

also i was watching the variable intake actuator and just past 5800rpm the actuator would open and close rapidly then slam shut at 6300rpm, i think this could definitely be affecting top end power as the power starts to fall off just after 6000rpm. i was thinking i could get an RPM switch and have it open the VI at whatever the stock point typically is (looks to me like 5200 but thats just me looking at it), i know the ECU bases the actuation on a few different things but if it wont affect power in a big way i dont see the issue.
any ideas?

edit: i have windoweld filled motor mounts, the front tranny mount is filled (windoweld) and the rear mount is welded to the tranny (long story but it works)

Greeny

iTrader: (43)

How did your dyno turn out? {numbers}

MaDMaX024

said and done 195hp/190ftlb
25* base timing, 12.5:1 AFR
i was most surprised that at 2000rpm, i'm making 162ftlb (62.5hp but thats irrelivent)
i was talking to aaron92se last night and he said the record for VE torque was just over 200ftlb..whats the HP record?

Matt93SE

iTrader: (44)

I played around with opening the VI sooner/later in the past, and all I did was lose power. be careful wen dinking with it.

MaDMaX024

the only affect the switch SHOULD have is keeping the VI open until i let off the throttle at 6500rpm as its closing at just about 6000...

Loe max

iTrader: (6)

I was under the impression that the powervalve opens at 3,500rpms?

Zack342

iTrader: (89)

not bad #'s. your turbo right?

MaDMaX024

uhh no...not yet. those are embarassing numbers for a turbo maxima.

MaDMaX024

i dont believe so..the VTC release is approx 3500rpm as is the knock sensor. i'm almost positive the VI opens alot later.

Loe max

iTrader: (6)

I see, I was just under that impression because I can feel a big push in power at 3,500rpms and since this link that SteVTEC had, VTC's close at about 4,500rpms http://www.v6performance.net/forums/...ad.php?t=15976

«§»Craig B«§»

iTrader: (5)

the knock sensor? The knock sensor has no idea what RPM the engine is spinning at.

Jeff92se

iTrader: (82)

You can blip the throttle and see the vi open. It should not close down. Maybe the solenoid is losing the signal or your vacuum canister has a leak. Or the actuator can't hold the vi open because of some leak.

KLoWnPR109

iTrader: (9)

He must be turbo to have more than hp than your car right?

MaDMaX024

the ECU ignores the knock sensor signal just around 3500rpm, i forget the explanation..thats what i was referring to.

MaDMaX024

yeh i have no idea...the vac system is flawless as far as i can tell, no leaks to speak of, all new hoses..how can i check the canister?
looking at my chart compared to other VEs it seems to be just about the same shape, power falling off a little at just about 6000rpm. its not falling off by much, but maybe i could've made a few more ponies if the VI stayed open.
has anyone else noticed this?

Jeff92se

iTrader: (82)

That is odd. Maybe at WOT but I can't see any particular reason why the ecu would ignore the KS at 3,500 rpm or pretty much any rpm

Loe max

iTrader: (6)

I call bs on the #'s, he doesn't have a Nismo radiator cap therefore, the VE would have blown up from overheating 5fwhp over stock.

MaDMaX024

IIRC it has something to do with valve train noise being picked up by the KS as..its the only explanation for julio's(boosted VE w/TTZ pistons) power coming on at 3500rpm. the fuel was perfect, the turbo would not spool more than 3psi below 3500 in 2nd or 3rd and even in 5th gear when it did the power was just not there, then all of a sudden it would make 8psi no problem by ~3600. it was very consistant and a problem that plagued him when the motor was stock, after the heads were rebuilt, when the block was rebuilt w/Z pistons, even still after he was boosted. previous to his dyno i was convinced the ECU would both pull timing and dump fuel if it picked up knock, but from what i've seen it only pulls timing.
a good experiment would be to go WOT a few times in say 3rd gear from 2000rpm-5000ish to calibrate the butt dyno, then disconnect the knock sensor w/o any kind of bypassing and do it again..i'm willing to bet power above 3500 is unchanged. i drove his car, i helped him test and retest pretty much everything and something in the knock circuit was dead.
honestly both driving and riding in the car, it felt maybe 10% as strong as my VE(even before when i had very low compression and a slew of other problems...one of them was NOT anything to do with the knock sensor)

MaDMaX024

thats 5HP more than what stock is at the crank
stock VEs put down what, 170hp at best?
no comment on the nismo cap

Loe max

iTrader: (6)

http://forums.maxima.org/showthread.php?t=345990 go through the pages and you'll see what I'm talking about

MaDMaX024

i already know what you're talking about but i dont want to start an arguement

mtcookson

iTrader: (2)

you'll probably gain even more power by running the afr up a little bit. generally you don't need to make it that rich unless you're boosting. otherwise, the numbers aren't bad.

subs1000w

numbers look great but can you post the printout

MaDMaX024

not yet, i'm not in the database so i dont have access to it yet..i'll post it as soon as i get it.

Jeff92se

iTrader: (82)

When I was boosted, I could feel the turbo coming in alot sooner than 3500 rpm. I have no way of measuring the psi level but I'm sure it had to be more than 3psi.

MaDMaX024

boost was irrelivent, the fact is on or off boost, below 3500rpm it felt exactly the same.

Jeff92se

iTrader: (82)

Okay. Mine still felt very good below 3500 rpm. but I had a T28 and not a T3/T4 hybrid.

«§»Craig B«§»

iTrader: (5)

so you're saying the knock sensor is responsible for that because you couldn't think of anything else? And then determining that the ECU works a certain way because of this quirk?

I really dont think that's the case. I dont know why the ECU would stop looking at the knock sensor like that.

MaDMaX024

whip out the FSM and tell me i'm wrong.


i'm done discussing my reasoning for thinking how i do about the knock sensor, mine works 100% and thats what i care about at the moment. can we get this thread back on track? if you'd like to discuss knock sensor issues with me, shoot me an IM, i love talking about maximas on AIM.

to get back on topic: so no one has noticed the VI actuator going crazy at just about 6k?
what about the motor shaking?

MaDMaX024

i dont doubt it one bit and with a t28 i'm almost positive you made more than 3psi below 3500rpm
i find it horribly strange that in that car, below 3500rpm stock motor, not stock motor, boosted, it made VERY little power. i mean, stock motor/stock compression, n/a on lower compression, and on boost it felt no different whatsoever below that point. like i said in my previous post to craig, talk to me about the trials and tribulations of julio's car on AIM, i'm more than happy to discuss everything i know about it and what was done. it'd be nice to find out i'm wrong and that there is a much simpler answer than something in the knock sensor circuit is very wrong and we could not figure it out.

Jeff92se

iTrader: (82)

I'm not sure there would be something that specific in the fsm but I could be wrong.

My car does not shake at 6,000 rpm but I also can't really look at the VI while inside the car.

But Mr. Gone has a rice light that tells him when the vi is on/off. I guess he could do a run and see if the light flickers at that rpm. But I would seriously doubt it

MaDMaX024

in the fsm it says something about which conditions each sensor/valve/actuator is active in..like the vtc solenoids are something like when engine speed is below 3800rpm or whatever it is, not at idle, coolant temp below a certain amount...


its not that the car shakes, the motor did on the dyno. i had my hand on the fender for a few runs and even though the motor was shaking like like it was misfiring, the graph/afr/overall feel was smoother than the motor movement indicated.


shawn's rice-light has nothing to do with this, i was simply asking for experiances from those who have been to a dyno. if you look at the VI actuator does it rapidly open and close several times before shutting (before the pull was over). had the hood been closed, i wouldn've have suspected anything was amiss, but it wasnt and i'd like to know if something is terribly wrong or if its normal.

subs1000w

i didnt look at the VI when i was on the dynop because i was driving but i did watch the engine and it didnt move and inch wonce it was under a load

MrGone

iTrader: (30)

1. no sheet no care
2. my rice light tells me when the ECU is telling the VI to open and it doesn't sound too far off
3. who wants to drive around with no hoods to verify
4. i'll read the entire thread tomarrow

blacks92seAuto

ya where is that dyno sheet

MaDMaX024

the place i dyno at makes all the sheets availible online, i'm not on the site yet. i'll post it as soon as its availible.

Jeff92se

iTrader: (82)

I pretty sure the valve will open cold or hot. It's the VTCs that only operate under certain conditions. But I'd have to look to make sure. But it's operation is fairly simple. I can even rev in neutral and have it flip open. Lower than 6,000 rpm also. Even teh 4-gen mevis are tuned at 5,000 rpm. 6,000 rpm is too high imho.

I didn't notice my car shake any more than normal. But then again, I was driving the car at the time also. Maybe the graphing is such that it hides it. ie.. big jumps in the rpm scale. I dunno

Actually it would. If yours is switching on/off, then his light would be blinking. That is if the ecu is signaling it to go on/off. If the ecu signal stays on and it's still going on/off, then it's a vacuum problem or the solenoid is flipping out.

BTW. In what gear and what type of dyno did you get this all done on anyway?

MaDMaX024

it doesnt start to open at 6000, it opens fairly low (not entirely sure), but at 6k it starts to flip out then shut.


i find it strange the dyno operators let you drive your car..oh well, the entire car doesnt shake, its just the motor....if no one looked and i cant notice it in the car, i'm not gonna worry about it.



i highly doubt its the ECU but i'll check it out this weekend

3rd gear, dynojet model 248.

Jeff92se

iTrader: (82)

Far as I know mine does not open/shut at that rpm. Doesn't make sense. But that's kinda hard to test unless I just rev it in neutral and watch

Not unusal here. They just say "stay off the damned brake at all costs"

Prob not the ecu. That was my point. But it could be the ecu. I'd confirm the signal at the solenoid.

Zack342

iTrader: (89)

where did you dyno>?