Questions for some of the more knowing...

FIrst off, yes. this is not the right forum, but try to get ANYTHING out of the J30 area and you'll realize why i am putting this here.


i'm wanting to put more inside of my car performance wise. It's a 93 J30t by infiniti. i already have bosch platinum +4 sparkplugs, pro rated fuel filter, a new pcv valve, and besides that, it's stock. what can i do that will increase my car's potential and not wreck my checkbook?


also

i've noticed that about 80mph my car begins to rattle and shake.. .but then stops at 90... i haven't a clue on what causes that.

oh, and also my car is idling really wierd (like 400-800 instead of 1100) but it fluctuates... like it'll be at 800, then drop to 200, the go up to 1100.


any ideas? ALL input is appreciated.

Is the car pretty much stock??

Plugs probably run too hot for it. Try a more basic plug. Maybe something from the factory.

nah it was doing thta before i switched plugs (the idling all of it...) and they are recommended for it as well (it's platinum tipped...)

You probably have some kind of Throttle Positioning Sensor that is causing your RPMs to fluctuate like that.

I would assume its in the TB somewhere, but I really have no idea for that type of vehicle.

ok, well what about performance? what can i do?

Yeah, it sounds like you need to adjust your TPS sensor. Lemme go check on where it is on the Tib. I'm pretty sure there should be some sort of screw on the TB that you can tighten down to fix that.

As for performance, upgrade the big 3: Intake/Exhaust/Headers. Lightweight pulleys would help too. You could also have the Intake Manifold bored up. If you do that, be sure to get a bigger throttle body.

If you have more to spend, you could get a fuel-tuning system, better fuel injectors, high duration cams, high comp pistons, etc.

It could also be your oxygen or MAP sensor.

As far as racing performance, new spark plugs, cables won't do pretty much anything that will make you go faster, unless the old ones were really bad. I consider new sparkplugs and a new fuel filter maintnance, not performance mods...at least not most cars on this forum.

You should check an infinity forum to see what the best mods would be. All cars respond to different mods differently.

a big ricer wing and lots of stickers will make it SOOO fast! :screwy:

hmm...the +4's are a waste of money i've heard...but i would at least modify the intake, headers, find a y-pipe, high-flow cat, exhaust.

As it was said by Mister Sinister (it woulda been me, if my internet hadn't crapped out seconds beofre I hit 'submit post', lol), the best bang for your buck is gonna come from Intake, Exhasut, Headers, and possibly a bigger throttle body. The engine is basically a giant air pump, and the best way to get it to work better is to let it breath more freely. Once you get those, see if you can find a chip or software to take advantage of those mods. Then, put your car on a diet.

Just a shot in the dark here, since I know absolutely nothing about your car, but does the t stand for turbo? If so, can the stock block handle more boost?

the shaking sounds more like you need your wheels balanced, since its only at a certain speed that does it, this means that the wheel is tramping and shimmying at a certain frequency thats causing it to shake. i think if its a tps sensor then it always bog down whenever it hits that throttle angle.

also if its the 02 sensor, he would notice a big drop in fuel economy. it sounds like either a unbalanced front wheel or wheels, lift up the front of the car, to check if your front end is loose ( check tie rods ends,ball joints, and wheel bearing ) you can check by lifting the up, and by tryin to wiggle the wheel. if it wiggles, theres your problem.

the T stands for touring.
iirc, that's detuned 300zx motor in that car. there are plenty of mods available for that thing.

for the poor idle, i'd say it's either the idle air control valve(iacv) or your PCV valve. Also check your Mass Airflow Sensor.

As it was said by Mister Sinister (it woulda been me, if my internet hadn't crapped out seconds beofre I hit 'submit post', lol), the best bang for your buck is gonna come from Intake, Exhasut, Headers, and possibly a bigger throttle body. The engine is basically a giant air pump, and the best way to get it to work better is to let it breath more freely. Once you get those, see if you can find a chip or software to take advantage of those mods. Then, put your car on a diet.

Without knowing too much about the J30 and what exactly is available for it, this is a very good guideline to go with, except I'd throw in an underdrive pulley kit (again, if available) as a good bang for the buck mod.

Also when to do the software depends a lot on what is available. With the exception of the bigger throttle body, most plug-and-play software won't have different programming for intake, exhaust, pullies, or headers. If you're going the custom tuning route, then you'll definitely want to do the software last.

also if its the 02 sensor, he would notice a big drop in fuel economy.


Not neccessarely. When I got the header in my old civic, the O2 sensor started acting up and I had an erratic idle, but I got better MPG. I was averaging over 40 mpg on the highway whereas it was less before that. Once I replaced it, it went back to below 40 mpg. The reason I know this is because I used to take the same long trips week after week and I'd have more gas left after the 02 sensor started acting up. A lot of people think the car always runs rich after the 02 sensor goes, but that's not always true. But you're right that the MPG should change since the ECU doesn't know how much fuel it needs. But it can also be a benefit MPG wise, but obviously you'll lose performance since not enough fuel is injected to go fast.

after re reading his problems, i didn't realize taht he also mentioned idleing problems.

then you should definitly check if the MAF sensor is plugged in right/tight, also your idle air controll valve maybe no good, or it your throttle position sensor could also casue it, or it could be as simple as a vacuum leak.

open the hood, hear for leaks or hissing sound. if theres non, then chances are you theres no vacuum leak. then your better off buying a voltmeter and probe the power wire, to each sensor, then ground it to the chassis, and see if your getting a right reading.

your maf should give out like . something volts at idle. since 5 volts is when it maxes out at ( which means its reading air flow for around 450 hp ) if your readin something ridicously high, that means the sensor thinks its reading too much air and is dumping a crazy amount of fuel.

on the throttle position sensor, leave the key on the on position but don't start the car. same thing with the volt meter and see if the voltage stays constant without anybody stepping hte gas. the TPS is a variable resister, it should read from 0-5 volts from open to close or visa versa.

you can also check if your running rich by pullin out any plug and see if its really carboned up, or if wet ( wet from fuel ).

My vote goes to the MAFS. Try wiggling the connector and cleaning the diode with a q-tip and rubbing alcohol.

Easy way to check for a vacuum leak is to use a vacuum gauge. They're not expensive at all and have a million uses.

Check the ground as well. Use a multi-meter and test the resistance from your battery negative terminal to an unpainted screw on the chassis.

For performance, I would start with a high flow exhaust system. Then intake, headers, high flow cat, and possibly a tuned ECU with a more agressive timing and fuel curve. Then start looking into internal mods and such.

i would just assume that they make a supercharger kit for your car as they do for the maxima, besides that i'd look into transmission stuff, to get it to shift faster and get more power to the ground, being an automatic and all

The idle problem could be the MAF, or it could be the MAP sensor, or it could be the TPS, or it could be the ECM, or it could be the O2 sensor....etc etc etc... Your best bet is to take it somewhere and get a diagnoses before you start replacing a bunch of parts that you dont need. You can't just say, oh i had that problem and this is what i replaced, now it works fine; Only in a perfect world will that be true. Take it to a dealer, get your diagnoses and if you can, fix the problem yourself.

Probably a vacuum leak or spark plugs, o2 sensors usually throw a CEL.

I/H/E usually the best place to start on any car.

port and polish

You don't usually even have to go to a shop to do a diagnostics. I know that on a civic you can use a paper clip to connect two wires by the ECU and you can get the code by looking at how many times the "check engine" light flashes. I'm sure there's a trick like that for your car too, just gotta find it.

Take it to autozone and ask them to hook it up, its free and easy so why not. I say intake, headers, testpipe, and maybe exhaust if you can afford it.

ok, well these are awesome responses! i already replaced the pcv valve, fuel filter, and spark plugs (did that because i thought it would fix it...) where is the MAFS located? and i'm considering taking it to autozone... don't they do the scanning for free? I know the infiniti dealer way overcharges for all repairs, so i'm wanting to do this myself as long as i can. I'm going to get it balanced tomorrow and get the alignment done again (lifetime alignment's = awesome)

if you can think of anything else, please share! what sites can i go to for headers, etc for my engine?

Yea autozone will scan your ECU for free, knowing how to interprit what it spits out they're not so good at (at least the dude had no idea what it was for my moms sienna).

#4 is the MAS, but this is a 3000GT NA engine. Look for a black box that goes to a smaller black box (with a plug in it, which is the MAS) that leads to a black pipe that connects to the throttle body which is attached to the upper intake manafold/plenum.
http://www.81x.com/Authors/tadryan/engine.jpg

As for headers just search for "j30 headers" lol. You might also try the 300ZX forum since somone said the engines are similar and they might know, they're real nice guys and will help if they can.

maf is the wire that connects to the intake itself, near the filter. and yes, i'm pretty sure autozone does it for free...so go ahead n do it. but you should be able to do most of these fixes by urself...a lot of the sensors are easily accessible.

I think in his instance there's going to be more of a focus on the data stream, unless he actually has some trouble codes present. And i dont think the scanners at auto zone can look at this info. They probably dont even know what a drive cycle is. Checking injector pulse width, O2 sensor signal readings, MAF voltage/frequency(whatever infiniti uses), MAP sensor readings and so on and so forth. Just like GM has the Tech2, i'm sure infiniti dealers have their own scan tools that can quickly go through and see the data stream.

http://www.majinarmy.com/images/Frankencar/repairs/engine.jpg


could someone show me on this picture under the hood?

Its the thing with the red sticker on it on the far right exactally halfway up and half inch in.

http://members.aol.com/vipmetal09/engine.jpg

I can walk you through cleaning it.. just call me up or w/e. If that doesn't do it, then we can look at cleaning the IAC valve.

well you have a 93, those don't use universal OBDII scan tool ports. i don't think autozone has the tool to scan any other car but OBDII cars.

good question.... i needa find that out (remember, i don't know my car 100% yet... that's why i'm here.. to learn more and to share what i know with others.. thanks for the insite, it's very appreciative

autozone by my house doesnt scan for free, they make u pay a $ 300 deposit and u do it ur self. for OBDI u gotta buy a scan tool, its like 30 dollars

Well I'll be the first to say you don't need that silly LSD in your car. Just remove it along with the axles and send them to me.:evillol: hahahahahaha

Just figured I would tell you that you have a Limited Slip Differential. That is if you didn't already know.

i knew that much :evil: lol

but i have a spare :even more evil: i own another j30 as well for parts...

Underground do you know where the ECU is in your car? it's usually on the driver side or passenger side footwell on the floor, behind the center console. there is a little flathead shaped screw on the ECU that if you turn it all the way toward you, then all the way back, it will make you "Check Engine" light begin to flash. it'll flash like 4 long flashes, 3 short, 2 long, that code would be 432. then you look in a haynes manual or something and find out what that trouble code means to find out what your cars problem is. it was like that in my OBD-1 maxima, i can't guarantee it's the same in your car, but it should be.

Edit:

here i found this for you.
http://www.troublecodes.net/infinity/-it even tells you what the codes mean

well for most problems of that sort doesn't your check engine light already have to be on? or is it one of those things it doesn't catch?

I don't know man..they spelled Infiniti, "Infinity"...so I don't know how reliable they'll be. haha.

well for most problems of that sort doesn't your check engine light already have to be on? or is it one of those things it doesn't catch?


If it's a catalyst efficiency harming fault it should. But since there isn't someone needs to get a scan tool and go in and look at the data stream.

if i'm fresh out of rubbing alcohol, should i resort to hydrogen peroxide? or would that not be effective?

update

got wheels balanced, rotated, and got the alignment done. decided to buy some alcohol tonight (rubbing) and will contact vip tomm about cleaning that thing.

i would have to advise against actually touching your MAFS. they're very delicate and expensive to replace. the actual element inside is about the width of a paperclip with a sensor that's like 2cm long. i messed mine up cleaning of air filter oil with a q-tip, which was $385 to replace, luckily i have a warranty and i'm friendly with the nissan guy. i would go to autozone, get electric parts cleaner spray, and use that instead.

I've cleaned mine a million times. Most of the time, it was trial and error to see if that was the problem. It was actually the problem like once. When you clean it, just be gentle. Anything on it should come off very easily with the brush of a q-tip.

any ideas on how to clean it? i dont wanna go at it blindfolded

when i clean mine i take the element out of the housing(6" black tube). it's held in with two star shaped screws. then i hold it out and spray it with the parts cleaner, let it air dry for a minute or two, and slap it right back in. if you're gonna use the q-tip and alcohol just dip the q-tip in the alcohol and lightly brush the q-tip along the metal element and sensor. if you want, i'll do mine tomorrow and take pics. it takes all of two minutes.

yea! that would rock man, i really appreciate it

The J30 has the VQ30DE right? Just do the same mods as me...easy stuff....intake, y-pipe, cat back exhaust

nah, it's a VG30. it's a 300Z motor. killah, if i were you the first thing i'd do would be to take off the that bendy, restrctive intake system and run two sets of intake piping and filters from your throttle bodies. Aside from opening up the engine bay, and looking much nicer, it'll definitely flow better and make some more power and would sound awesome.

as for cleaning your mafs, there's two ways to do it. you can dissassemble your whole intake system, or do like i do and just remove the sensor:
this is my MAFS:
http://img.photobucket.com/albums/v379/BP2k2Max/Project16.png
take out the plug:
http://img.photobucket.com/albums/v379/BP2k2Max/Project15.png
then go to work undoing the two screws holding it down, they're star shaped and kind of a bitch to find the right bit to remove them:
http://img.photobucket.com/albums/v379/BP2k2Max/Project14.png
This is the MAFS taken out of the housing:
http://img.photobucket.com/albums/v379/BP2k2Max/Project12.png
the two sensors are:
the main sensor, which is what you'll want to focus on cleaning. this is the delicate piece, if you're gonna use the alcohol and q-tip be very gentle on this part.
http://img.photobucket.com/albums/v379/BP2k2Max/Project17.png
and this lil sensor here at the bottom, just twirl the q-tip aroundin there.
http://img.photobucket.com/albums/v379/BP2k2Max/Project13.png

I clean mine by just spraying on this stuff, it's quick drying and says it requires no physical cleaning.
http://img.photobucket.com/albums/v379/BP2k2Max/Project11.png

before you plug your MAFS back in and re-energize it, make sure there is no alcohol left on the sensor or it'll blow when you turn the car back on.
Another way to do it would be to just take the whole MAFS and housing and spray a shitload of the electric parts cleaner down into the housing

Nice write up man. I usually don't use a Q-tip when cleaning mine. I just spray it really good with non-chlorinated brake cleaner; gets it nice and clean.

i'm going to do it tomorrow after school (just bought the cleaner tonight) i'll let you know the results

nah, it's a VG30. it's a 300Z motor. killah, if i were you the first thing i'd do would be to take off the that bendy, restrctive intake system and run two sets of intake piping and filters from your throttle bodies. Aside from opening up the engine bay, and looking much nicer, it'll definitely flow better and make some more power and would sound awesome.
The VG30 has 2 TBs? Learn something new every day :icon16:

The VG30 has 2 TBs? Learn something new every day :icon16:not all, i guess just the RWD equipped vehicles, i'm sure it's becuase of the Twin turbo 300z. the VG30 in my old maxima only had one TB. killah posted a pic a few pages back, if you look, you'll see there are two TB's. it looks awesome with two CAI's hanging down with the filters behind the bumper. the only thing i don't know is how you'd connect one MAFS to two intake's.

killah, you can't clean your TB tomorrow. Gran Turismo 4's comin's out, son :iceslolan. too bad there are no maxima's in it though. :mad:

Gran Turismo 4's comin's out, son :iceslolan. too bad there are no maxima's in it though. :mad:
Boooooooooo!!!! :mad:

heh, don't worry, there's time for both (bro's getting it so i don't have to) but i cleaned it. havn't driven it yet... i couldn't get it out of the slot... it has a seal around it that was a bitch to get around, so i just sprayed as much as i could in it and around the plug. hopefully it would work.

btw, how else could i fix the vibration at 60? (after the balance it vibrates at 60 instead of 80...)

i read about the driveshaft u-joints... any idea where they are?

one set of u-joints connect the driveshaft to the tranny, the other set connects it to the differential.

update :

today after cleaing... try to start car... won't start


dad comes home (i'm late for work) he get's it cranked ,but won't go over 3krpm

tonight (mom brought me ot work and dad took me home) sit outside with dad, holding his beer while he wonders what the hell happened. We go to the parts car (the other j30) and take the sensor from it

replaced


works fine

still idles badly though, but at least it's running again. so cleaning it wasn't the problem.

Now have some fun with the cleaner stuff, if its anything like throttle body cleaner everyting in it is highly flamible lol, 7 foot flames out of the can easy haha. I think I'll go get some of that tomorrow and try to melt the snow off the driveway heh.