Code P0303

[Mopar]

I got a check engine light last night and checked it was Misfire in cylinder 3. I took out the coil and the spark and everything seems to be ok. I put it back together and my car still chucks and vibrates and hesitates on acceleration. What do i need to change in a misfire, the coil or the plug or what?

[Q45tech]

Depends! could be a dirty injector or a dirty intake valve or plug or coil or ecu or bad rings [low compression].

One usually changes spark plugs, examines and cleans the coil boot and uses BG44K to clean injector and valves as the first step.

[Mopar]

ok done that, what do i do next? change the coil?

[gjh20]

I got a check engine light last night and checked it was Misfire in cylinder 3. I took out the coil and the spark and everything seems to be ok. I put it back together and my car still chucks and vibrates and hesitates on acceleration. What do i need to change in a misfire, the coil or the plug or what?

i have the same problem, except my miss is so random that it won't trigger the check engine light so that i can single out the cylinder. i bought a new coil & have been playing "musical coil" to try to figure it out. i will seemingly have the prob identified & it'll run good for a few days, then the miss returns. i hope someone can help us out Mopar because $250 apiece for 8 coils is not easy to swallow (especially considering it may not solve prob).

[Mopar]

I am thinking of buying a coil and playing that cat and mouse game with my plugs, since today it turned into random misfire. don't know what to do! and I got so used to the shaking of the car at red lights that today i was sitting in a friend's car and it was so nice without the earthquake!. Please someone adivese.

[maxnix]

i hope someone can help us out Mopar because $250 apiece for 8 coils is not easy to swallow (especially considering it may not solve prob).

Only ~$173 from Joe.

There are two types of coils on a VH41DE.

If a cylinder misses, there will be a code usually along with a KS code .
Modified by maxnix at 8:19 PM 6/5/2007

[KU4FIZE]

funny, i only got one code?

and 173 dollars for coils is it for all 8 or just 1 coil?

what type of coil do i need/looking for since there are 2 types.

[maxnix]

Per coil pack. There are 2 different types, so it depends which type (which is dependent on the cylinder) you want to change out.

Only one code is fine. KS code is normallly also generated with a misfire.

[gjh20]

wow. was totally unaware of there being 2 diff coil packs. i bought mine from Infin & wasn't asked which cylinder the two were designated to replace. can you elaborate on how to know the differences a bit more? its a shot in the dark, but i may have wrong coil pack on wrong cylinders...

[maxnix]

Just look next time you are there. One type will not fit on the other type, I believe.

I may be wrong, but when I ordered from Joe I specified the cylinder where the coil pack was installed. In my case it was 2 and I switched with 4.

[gjh20]

i've pretty much exhausted the possibilities in the game of "coil switcheroo" & didn't have any coil fitment issues. i dunno. honestly, i'm frustrated as hell & just want it to go away.

[ZMARKUS]

Amen brother, I feel the same way. Why in the hell is the issue so common but it seems the resolution evades everyone. Infiniti dealers with their bend over and take it high labor prices should be ashamed not to be able to identify this cause more efficiently.

[maxnix]

Well, it's very simple. If the problem follows the coilpack, then it is the coilpack. If it does not, then it is the plug or the injector or their respective harnesses.

The above presumes you have a clean intake, TB, EGR and IAC valve, new fuel filter, air filter, properly working fuel pump. Must eliminate all else first.
Modified by maxnix at 8:29 AM 6/1/2007

[Q45tech]

To meet emissions idle AF is leaner than ideal, after the coolant warms up!

Does the misfire occur during warmup or after 10-15 minutes is a clue.

With a Consult you can manually increase/decrease injector open time to rule out lean misfire. How many 0.00 miisecs before other cyclinders misfire...how much is reserve.

One treatment with BG44k may not clean everything to as new condition.....why BG makes a rail flush system.

When you change spark plugs IMPORTANT to examine the piston crowns for deposits [fiber bore scope or just a fiber flashlight] ....the problem is seeing into the rear cylinders.

Gasoline may be the cause, as it is different from classical version used to test engines. Premium on the pump only means it costs more.

Change brands, change terminal fill locations, substitute some 100 octane racing fuel to zero in on the cause.

[maxnix]

Yes, fuel may be erroneously presumed to be good. Tier one premium only from a new location.

Always worth running a bottle or two of ISO-HEET even before a can of BG44K just incase there is condensation.
Modified by maxnix at 8:20 PM 6/5/2007

[Mopar]

well my misfire happens AFTER my car warms up. But for the past 2 days the misfire went away?!?! only today at a stop light it misfired once and that was it?

[gjh20]

got 2 cans of 44k for $23 bucks. i am halfway thru the 1st can/tank & can easily notice a difference in engine response. thanks for the advice! i know i'm jumping the gun on this part (BG rep told me 2 run 1can/tank, thn a full tank, thn the 2nd can/tank), however, my mis is stronger than ever. i'll be patient until i complete the 44k process but i'm anxious to know the next piece of advice on how to fix/proceed.

btw, my miss occurs on start-up then frequently surfaces during idling, acceleration

[maxnix]

btw, my miss occurs on start-up then frequently surfaces during idling, acceleration

So tell us about the condition of the plenum, EGR and IAC valves, TB, lower plenum runners, and the EGR tube within the plenum. Fuel filters?

Any not pristine as new?

[xerexabante]

check your plugs to see which one has more carbon build up. thus this will tell you that there is unburnt gasoline. might work

[gjh20]

So tell us about the condition of the plenum, EGR and IAC valves, TB, lower plenum runners, and the EGR tube within the plenum. Fuel filters?

Any not pristine as new?

as much as i hate to admit it, i can't answer any of these questions. i have moderate mechanic skills & honestly don't know what all those parts are or how to assess their condition.

[gjh20]

check your plugs to see which one has more carbon build up. thus this will tell you that there is unburnt gasoline. might work

i'll check that. also, the miss didn't begin until i replaced the plugs during a major tune up a couple months ago.

[Q45tech]

AH HA! When you pulled the coil out to change the plugs you probably damaged it going out or back in...........................this occurs sometimes.

[maxnix]

as much as i hate to admit it, i can't answer any of these questions. i have moderate mechanic skills & honestly don't know what all those parts are or how to assess their condition.

Couple of posts on removing the plenum to get to KS on Infiniti Online Mechanic. Only way to know is to look, or assume at 60K - 70K -80K+ miles if not known performed by then.
Modified by maxnix at 8:02 AM 6/9/2007

[Qproject]

could it be that maybe it's not related to the coil packs/spark plugs ?

I get a stall sometimes which triggers my "TCS traction control system" light to come on.

this happens very randomly.

[maxnix]

could it be that maybe it's not related to the coil packs/spark plugs ?

I get a stall sometimes which triggers my "TCS traction control system" light to come on.

this happens very randomly.

Yes.

Coold be a failing alternator, failing battery, or both.

[gjh20]

AH HA! When you pulled the coil out to change the plugs you probably damaged it going out or back in...........................this occurs sometimes.

assuming you may be correct, how would i isolate the failed/damaged coil if i am not getting any codes?

[Q45tech]

Chicken or egg, I wonder why they have upped the plug replacement [to 100k] interval? So the chance of creating a bad coil [at 60k service] rise beyond the powertrain warranty?

[qship96]

Chicken or egg, I wonder why they have upped the plug replacement interval? So the chance of creating a bas coil rise beyond the powertrain warranty?

after looking at the infiniti service schedule on line at corporate website,it appears they dont even list any sparkplug changes anymore,lifetime plugs? check out the newer q or m45 service logs online !

[Q45tech]

Lifetime is a misnomer inthat legal lifetime is 100,000 miles.After that point the car is supposed to be retired and crushed/ sold for scrap.

Just because some last longer in not germain.

[Qproject]

ok so any updates on this ?

this has been the biggest mystery in y33 history.