rough idle, my plans.. anything else i should do?
 

money is tight, so im seriously sitting here debating a few things.
Such as, knock sensor.. its $170 and alot of work. But my car has 130+k miles and i DONT know if its ever been changed, most likely not. Should i just sat F' it and change it?

Other stuff im planning on

Plugs
Remove & clean injectors, replace with new o-rings.
Fuel Filter
PCV Valve
Oil & Filter
Recharge my k&n air filter, or perhaps buy a pop or cold air finally.
MAYBE buy 4 new coils ( 2 rear, 2 front) already have 1 of each within 1 year.

Ive heard alot about cleaning the MAF (special solvent?) I have NEVER done a tune-up on a max or even a car like one yet before.

Anything else i should do, for a general maintence/tune-up.. get er running right

Sounds like you just have a miss somewhere.

You can measure resistance on the knock sensor to check its status. Same with the injectors, if they work but 1 is bad and causes the rough idle, dont take them all out. Dont clean them either, if it works fine then leave it alone because its best not to disturb them.

If you suspect a coil issue, try swapping them between different cylinders to see if the miss follows the coil.

Your k/s is most likely bad if it has never been changed..but it is most likely not the cause of your rough idle issue. Check your ecu for a bad k/s ghost code(bad k/s usually doesn't trigger the check engine light=ghost code)

Definitely replace the plugs/pcv valve if you haven't done this recently..As already stated, Do not pull the injectors to clean them, nissan injectors fail electrically, not clog, so cleaning them is pointless.

the Coilpacks on these cars tend to fail under load(accelerating) not at idle, however a bad injector will give a terrible/shaky/rough idle, and a pronounced shake when you accelerate. Unplug each coilpack plug one at a time with the engine running at idle, while listening carefully to how the engine sounds while each coil is unplugged, if you find one that doesn't change idle/roughness of the idle, then you found the problem. swap the coil out with the one next to it to see if the miss follows the coil, if the miss stays on the same cylinder, then you have a bad injector..

good luck.:)

KS; 5c resistor bypass is THE heresy that keeps my VGE running, since -04.

(bad knock sensor usually doesnt trigger the check engine light
and stores it in the self diagnosis on the ecu right?)
must not be that important to not trigger the check engine light

does anyone else think 92-94 ve dohc maxima knock sensors are an early
primative version thats really only on or off until they break
and trick the ecu into thinking the engines knocking which retards
timing and makes the customer belive anything could be wrong with
the car
and 89-94 vg sohc maxima knock sensors do even less since that motor
has a distributor unlike the ve 's power transistor which can vary timing
without turning a distributor and i never hear of vgs with bad knock sensors

ive been using the knock sensor bypass on my ve 92 auto dohc maxima
on a kinda frankin engine (except its running fine)for the last 15 thousand
miles of hard drivin (alot of delivery driving and road trip to the kinda-
off road up the mountain trail on a 95 dregree summer day with the air
conditioner on most the time)

so in conclusion i find 15 thousand miles later and still going fine
that the knock sensor bypass is fine on OUR TYPE OF MOTOR

AND THE ONLY THING KNOCKING IS IN THA TRUNK BOOM ,BOOM BUMP

KS is a [global] safety feature. When gas is good, engine clean, ambient conditions ok, safety features are seldom needed. Whole car-century went by without KS tech...

One way to keep our low rpm engines clean, is to run time to time '5miles over 5k rpm'... I guess this 'Grand Canyon-flush' also cleans gas-gunk sediment from injectors. At least this seems to do some good: idle becomes more steady, emission tst numbers are better.

Shops use gold-pricey gas cleaner additives to pass inspection - creates nice revenue with happy customers.

yea KS seems kinda pointless to me.. seems like some kinda "idiot proof" idea.
if i hear a pinging or knocking, i would know.. lol, my engine runs good for the most part.

thx for the info greeny, gonna check my injectors soon, and i never would have known its a bad idea to clean them.. figured it couldnt hurt.

NOW, how do i bypass the KS? :)

is that an additive, or just actually driving for 5 miles with motor at 5k rpm's or higher

1. on a low compression motor with factory timing the KS is not needed
2. the KS is a microphone, not a switch
3. the VE is modern high compression motor that uses the KS to prevent detonation due to variances in gas quality, elevation, and other factors that affect the detonation point of the fuel.
4. Unless you are consistently running 93 with your timing set to stock or less, leave the KS intact and functional

Going to inspection, I do the 5k rpm stunt for few miles, driving on 1st gear [that is a global safety precaution to keep u license]... I have no scientific proof - but the VGE typically runs so low that soot buildup on all various systems is more than probable; fuel system, soot on pistons, valve stems etc. The 'globbal WARmup -stunt' gives the soot a greenpee KICK.

The KS is :
a. good form Nissan point of view = keeps em running past warranty
b. very good business revenue expansion strategy = also happy $tealerships
c. useless nuisance for me
d. a 50c pretensioned piezo buzzer in an Ni$$an pckg
e. Keeps most [dead KS] ol Nissans guzzling gas = happy oilsheiks

My KS bypass http://www.cardomain.com/ride/748507/9

http://memimage.cardomain.net/member...748507_157.jpg

so i guess i really shouldnt bypass it?

well, i wanna check the resistance of my injectors, but i dont see where to make contact with the omhmeter. Where do I touch the points on the injector? (stupid question, i know lol)

yea, i actually found that write up while searching google, says to use a 500Kohm resistor, which AdvAuto couldnt help me with.
I at least want to bypass it to see if it makes a performance difference, if it DOES, then im left with the option of leaving it, or replacing it.
how do i get my hands on a 500kohm resistor??

radio shack

1st open the hood... Pins come visible after injector connectors are pulled up, theres the connector lock wire... and I broke almost all of em :( Doesnt matter, usually they will not need the lock. I guess (?) u can measure the pins also connectors NOT disconnected ... but then you cant see the possible oxidation and cleanup need. You may also listen em injectors clicking with a stethoscope (or long screwdriver) and compare.

Bypassing a safety feature always involves a risk. I think the LIFE is such a big risk ... each of us will die trying to save it:( ... opening the hood is already a huge risk, you will become responsible... like the life you have been given. Ppl say that 240VAC kills - if that was true, I was dead x100. So that claim is only somewhat true: 240VAC kills in certain circumstances. In my opinion, driving a car is the biggest risk of all those. Take care and be happy; to me this includes KS bypass :)

Radio-Shack etc electronics shops sell resistors '5c apiece'. Its easy test... I guess (?) the only reliable way to test KS is Nissan Consult. Ask dealership how much that is (maybe 100$).

unplug the connector. check it for corrosion. touch the leads of the multimeter to the 2 male prongs on the injector.

i figured if i unclipped the injector, it wouldnt have any current passing thru it.. so i was trying to poke around on the outside lol
I just tried to test the ohms for my KS,and failed, not the KS, but me.
i couldnt get a reading, ive never used one of these before.. its on the ohm setting, but what range should i be in? 20, 200? +2000 or whatever they are.
And i disconnect the wiring harness for the KS, do i check the pins that go TO the KS or the pins that go to the ECU? um.. motor on for checking the KS too?
man, so much i dont know, it sucks.
Do chilton books provide all these little details?

yeah, try radioshack, fry's, or any store that sells electronic parts.

thx, descriptive helps me :D

KS: Disconnect the connector (near temp sensors), measure between the pins on sensor side - NOT on ECU side.

Ohms Scale, upper scale ... try to get any reading. As said, this often fails, Nissan Consult Tester is the real option (?) besides bypass testing.

Bypass R is installed on ECU side, just to hoax ECU.

Chilton is a comic book; if you are not yet confused, buy it, try it...

thanks, hm, well.. im off to radioshack, then back home to bypass, shower, and take a ride to my gfs.. i'll post back if i noticed a difference
or if my engine blows up lmfao

radiohack only had 470kohm and 1Mega ohm resistors, i bought them both, trying the 470 now..

also, i unplugged my coil packs one by one, rear bank, left side.. does NOTHING when i unplug it, the rest make the engine bog down for a moment

sign of a bad coil? spark plug?

swap the coil with a known good one(on the car). if the same cylinder has problems, its more likely an injector. if the "new" cylinder has the same problems, its the coil.

Yes as benstoked says - generally dead cylinder. Worst case is burned valve [rare; if suspect, do compression tst]. As said, clicking injector is most probably alive.

When plugs are out, its good to do the compression tst on all cylinders and mark results for later use - compare. Reveals cylinder/piston ring & valve condition. Compression tester is '10$'.

2pcs of 1MOhm resistors tied parallel makes 0.5MOhm; your .470MOhm works... If KS is bad, youll find much better performance, if KS is ok then no difference.

The ECU on the VG controls the timing in the same way the ECU on the VE does.. via a power transistor. The difference is the VG uses only one coil and therefore requires a distributor. This does not affect the ECU's ability to control the timing.

I think you are getting confused with the old Kettering type ignition system which used points and weights.

while it serves the same function, the necessity of it is different

well i swapped the coils, put a known good one in there.. no difference

plus i pulled that plug up, runnin rich, it was covered in an oil/gas mix.. obviously the injector.. correct?

funny thing is, even with 1 cyl not firing correctly, my car still runs great. haha just that lil stumble of an idle.

and why the rear bank? now i have to take so much apart for an injector?
well, since im going to have to do ALL that i might as well replace the KS for good measure while im in there. sigh, there goes next weeks pay lol

but first im going to try swapping out the plug, rather it be the plugs just not sparking so its getting coated in oil/gas.. then have to change FI. longshot? find out tomorrow. lol

pull the plugs and look at them.

Most probable. Swap the plug...

If piston oil ring is broken, it will soot the plug, causes misfire. Get the compressor gauge while there...

Listen to your injectors click. Get stethoscope or long screwdriver: insert on injector, ear on handle [NOT vice versa:]

--------------------------------------------------------------------

'Cleaning' engine, injectors using hi rpm: worn engines 300kmiles(?) may have an formed an edge on top of cylinder. In case former user has never been racing the engine, the first time its done, hi rpm's will cause pistons fly against this edge - this will destroy all pistons into bits.

Cleaning fluids: From garage owners point of view its safer to use seafoam -like cleaners. At a shop they cannot possibly know customer engine history, and would be out of business if they were 'cleaning' all engines just by hitting max rpm's...

Typical way to clean a carburettor engine is to administer water down the throat [waterboarding?] while keeping rpm up. One teacup a time, pour in little water until engine starts to stutter. This steam cleanup is effective. This may also be tried on injector engine... I havent figured out how to administer it in VGE, so I havent done it (maybe via upper intake attached hoses?).

KS bypass: I know my engine history from factory, its clean, low miles, cold weather, lowest octane is 95 - thus I can also safely say that my KS bypass will not do any harm to my engine. (My ign timing is also advanced 2 degrees, now 17). Hot weather, sooty engine, not correct ign timing and KS bypass is recipe to destroy engine. So if bypass is done, ign timing should be checked, gas octane known, clean engine before driving in hot weather with full load.

[QUOTE=sonicii;6289855]The ECU on the VG controls the timing in the same way the ECU on the VE does.. via a power transistor. The difference is the VG uses only one coil and therefore requires a distributor. This does not affect the ECU's ability to control the timing.
QUOTE]
Im not tryin to battle here i might even learn somthing...now, I can understand how turning the distributor by hand can adjust timing
because the rotor to (dist, caps)contact points change(to either
a bit earlier or later)in relation to piston position(as in 15,or 17 degrees
before top dead center)AND also understand how an older type distributor
uses a vacum signal to move the vacum advance whichs duplicates turning
the distributor by hand .
but cant really see how that can be duplicated electronicly(by the power transistor ON THE VG...... pg.EF & EC 15(92 F.S.M)"power transisitor"
"The ignition signal from the ecu is AMPLIFIED by the POWER TRANSISTOR
which turns the ignition coil primary circuit on and off ,inducing the proper
high voltage in the secondary circuit .the ignition coil is a small molded
type ....no mention of timing
now the VE power transistor is way different because it controls
each of the six coils on off timing not just one

ive even been running regular unleaded (no specific gas brand)in my
ve with the 470k knock sensor bypass

one more advantage to the cars being not worth much anymore
i always give it plenty of pedal and feel the vtc boost
its an auto but i have a whole vlsd 5-speed swap sittin around
so im given the auto a workout since i have a backup upgrade plan
the 5- speed had bad input shaft bearings till me and my friend
"maximacgyver'd"the new bearings on since we had no hydr.press
and the 5 speed's all clean and still left apart waiting for a budget swap in or
futher rebuilding beforehand (i do like the auto since my 91 vg and my truck are stick)
so maybe the 91 vg-5 will get the vlsd-5 treatment .well see which one needs it first

when my ve knock sensor was hooked up it only lied to the ecu
when it got warmed up then after double triple checking
all the usual suspects i drive to radio smack and spend a dollar for 5
-resistors, plug er in and get er dunn my car went from a 500
clean ve auto with a "mystery" problem to more like 2-2500

[QUOTE=maximagician;6292506]You are quite right - the actual power transistor can do squat ito changing or controlling timing (if its working as intended anyway).

You did however conveniently left out the important part of that feedback ie "The ECU on the VG controls the timing in the same way the ECU on the VE does" ........................ ECU determines, using various sensors, the current ambient and load conditions of the engine, and from that, using a fixed and pre-determined "map" of optimized timing values for those conditions, only trigger the coil/s via the power transistor at the appropriate point in any given engine revolution - ie - the power transistor acts on a switching signal from the ECU.

The power transistor is nothing more than a modern version of "a set of points and condenser" moulded in a plastic package that you are used to find on older mechanical (speed) and load (vacuum) varied distributor timing - consider the modern ECU to be the equivalent of the older points/condenser mounting baseplate.

even with a distributorless ignition ignition system there is still something that picks up the engines timing and in the case of a VE can be easily adjusted to fool the motor, effectively changing the timing.

I guess the safety-margin is quite large. Some say that they use 25dergees advance... Still its not good to generally advice ppl beyond any 'danger line'.

If my Maxima was young, I would not use any bypass but let stealership gouge my engine & deep bank account. However, 3gen maximas and deep accounts seldom go together nowadays...

well, id say my KS is fine, and bypassing is maybe not the best idea.. least for me!
my car acted strangely, rather than better.. so obvious sign my KS was fine.. so i took the bypass off.

changed the plugs yesterday, filled up with some mobil.. my idle seems to have smoothed out, but i know still.. if i unplug the rear bank left coil, there will be no change.
so its kinda scaring me into thinking its the cylinder

this is only my 2nd vehichle, makes me miss my 88" yota pickup.. that thing was cake to work on. And it was the 22re engine, solid
but i love the balls a 92 maxima se has.. if i had the money id make my car "brand new" again.


COMPRESSION check.. ok, how does one check the compression on the rear bank side, its like 8" deep.. please tell me i dont have to take the intake plenum off to check compression? I can only thing of the usual compression tool ive ever seen or once used

simple: get a compression tester(you MAY be able to get one as a loaner from som parts places)kinda like This one., depressurize the fuel system(pull the pump fuse, let it run til it stalls, start again, repeat til it wont start up), remove coil and spark plug. install tester into spark plug hole(doesnt have to be tight, you wanna be able to remove it), have somebody crank the engine while you watch(some gauges have a maximum psi needle that you can reset, others hold the maximum psi til you push the release), reinstall plug/coil, and move to the next cylinder, repeat. do all six cylinders.
note: may wanna have a battery charger available. that few, short cranks shouldnt kill the battery, but better safe than sorry.

LvR covered it fairly well. The power transistor itself does not adjust the timing, just as the power transistors on the VE do not adjust the timing, the ECU adjusts the ignition timing and drives the coil(s) via the power transistor(s). But the ECU only varies the timing from the base timing setting. The Base timing is set by adjusting the Crank Angle Sensor, on the VG, the CAS is in the bottom of the distributor unit, on the VE it at one end of the front bank (as far as I know). Turning the CAS changes the phase between the actual crank position and the sensor.
The CAS is responsible for telling the ECU what position the crankshaft (camshaft to be accurate) is. The ECU offsets the ignition timing from the base setting based on several other inputs (RPM, Throttle pos, Coolant temp, etc).

I should also point out that if you could just turn the distributor cap, without turning the CAS, you would not change the timing. The timing is determined by firing the ignition coil which is done by the ECU. If the cap could be turned far enough it is possible the spark would be sent to the wrong cylinder though!

Hope this clears things up.

yeah. compare the contacts on a maxima
http://i242.photobucket.com/albums/f...1635888BOS.jpg

VS. a chevy (I think, doesn't matter, the contact is about the same size)
http://i242.photobucket.com/albums/f...DR311Rotor.jpg

anyway, the contact point on our cars is significantly wider. this allows the ecu controled coil to manage when the spark is sent, rather than just the dizzy with a (pretty much) always hot coil(respectively).

part of it has to do with the diameter of the cap and how many cylinder it's firing.