98 camry engine light on w/misfires & system too lean

You have to determine which cylinder is doing the misfire. It may not be an ignition problem but possible injector problem.

NO CHECK engine lamp (CEL) glowing running???????
which engine, there are more than one engines, offered on most cars.
that is misfire. and misfire is complex.
there are 50 causes of misfire, on Otto cycle engines (gas)
http://www.fixkick.com/misfiring.html

and more if flooding.
hot or cold engine?
or both?
ever do the 60k tune up?
id bet the engine is good, so we can remove 1 of the 3 main causes.
1: bad engine , no
2: bad spark, id bet not if miles is low, is it? below 60k?
3: bad fueling.
that is the proper order,
so if car is tuned up and spark is good.
then it must be fueling. so we connect the scan tool (any Can-bus)
and see DTC errors and it MIL active.
ok its sees misfire P0300s?
if no errors and its misfiring.
we then look at all sensors live with the scan tool.
id bet the engine dont hold closed loop hot, idle , as it must.
screen says, CL = active, or like kind.
if v6, there are 2 banks that must be in closed loop status.
I'll stop here, but will say I have a battery of tests for CL failures.

one is to make sure the 02 sensors work right and that there
are no exhaust manifold cracks near any 02 sensor.
i try to force the engine leaner and righter (tricks) that might
wake up a dead 02,
to see if it swings. (called cross counts)
the causes are many if the sensors are good.
fuel pressure out of spec,
injectors bad, leaking or clogged.
bad fuel.
dirty MAF sensor.
ECT stuck at wrong temperature for any reason, 180F or more is good.
and more... ask.

how many miles on the odometer, mines 95k.
ah a v6, P0306 is #6 misfiring. 2.5L V6
300 is all 6 misfiring.... oops.
it is. for sure.
misfire is cause by many things, only 3 in physics, but many real world. (compression + spark +fuel rates)
i works this easy, way.
i have a full scan tool not just a code reader (near useless it)
i make sure my V6 (I have an 04) holds closed loop at idle and 2500 rpm. i f not , fix that first.
easy, it is. just look, bingo, Open loop, (out of control)
fueling is out of control.
but, first i do that tune up. in the manual, 60k , 120k, 180k, see?
do that first. , spark plugs dont last foreever nor filters.
then i replace both front 02 sensors at 100k miles. there design life.
V6 has 2 front sensors. (rear can , just sit and be ignored)
if it misfires. now, i toss a coin.
compression or fuel pressure.
i can do both in 30min flat but i toss coin lands on fuel.
i check fuel pressure and its.
60psi, fuel regulator is bad,
20psi, same, or bad pump or bad 12vdc to pump, 8v to pump is bad wiring.
one thing that helps is to find out if the engine is running too rich or too lean.
and if there are cracks in the exhuast near the 02 sensors.
i force the EFI rich and lean watching both 02 sensors in my scan tool
to see if i can force them lean or rich.
on the v6, we can introduce air leaks, to the plenum.
this will cause lean, and the o2 most react to my lean forcing
or its dead.
i can force richer, if i suspect lean or 02 shows lean, by
removing the Fuel pump regulator hose (vac) and plugging hose fast.
this causes the FPreg to go to high pressure. max.
causing RICH>
i watch the 02 and see it go rich, if not the 02 is bad or you have exhaust leaks, or dead cylinder causing the 02 to fib.
you have 2 banks, and both banks are running off 1 MAF
so you can look at both 02 sensors (front) B1S1 and B1S2
and see if both react the same. to my forcing's.

i dont think you have 3 bad cops out 6. no.
if any cylinder misfires on bank one, then bank 1 o2 goes nuts
same with the Bank 2. this can aid troubleshooting having 2 banks.
the MAF can not lie for 1 cyclinder nor one bank
the 02s can lie for each bank,
both are key to diagnosis.
let me give an example say
injector 1 leaks.
causing 301s
v6
246
135 left
this is your lay out.
my guess is its not lost compression (no test guess, mostly useless)
not 2 bad cops one on each side will cause 300s
not one bad cop. as other side would be ok.
not one bad injector.
my guess, is fuel pressure is way off.
but///???
or maf running lean (dirty, spary clean it 12inches away not close)
low fuel pressure
too high fuel pressure.

all comments are for engine with 60k mile service done,
60k, 12ok, etc.

You might want to check the wires that go to the 02 sensor it sounds like when the tune up was done the wires may of become dis-connected. Unless of course the tune up was done to correct the problem. In that case first check for gas leak under car and around gas tank, if OK then, next ( I take it there's no check engine light on) borrow a fuel pressure tester from Auto Zone and test the fuel pressure After you've hooked up the tester run the engine a few minutes then shut it off and watch the gauge it it slowly drops you more then likely have a leaking fuel injector.If in fact this is the case, before you replace the injector run the fuel down to 1/4 tank and add a good fuel injector cleaner to the gas and run until close to empty. Put fuel in tank and drive at least 50 miles to allow fuel system to clean out. If still the same then the injector is bad. Note; You could also have a bad 02 sensor but that should set the check engine light.

p 0300 code is for random misfires
random misfires are more from dirty /faulty injectors or low fuel pressure than anything else
have a pressure test done to check pressure regulator , filter and pump operation
use a can of quality injector cleaner or remove and clean the injectors

P0301 - Cylinder 1 Misfire Detected.

Causes:
- Improper spark plug at cylinder #1
- Insufficient compression at cylinder #1
- Incorrect fuel pressure
- The injector circuit is open or shorted at cylinder #1
- Fuel injector #1 may be faulty
- Intake air leak

Solutions:
- Perform Injector Service
- Replaced Spark Plug #1
- Replaced Injector #1
- Replaced Ignition Coil #1

P0303 - Cylinder 3 Misfire Detected.
Follow info from P0301.

P0316 - Misfire Occurred In The First 1,000 Engine Revolutions.

Causes:
- Damaged CKP sensor.
- Ignition System.
- Fuel Injectors
- Running out of fuel
- Fuel Quality
- Base engine
- Damaged Powertrain Control Module

Solutions:
Usually the P0316 is combine with a P03XX codes. The P03XX code indicates in which cylinder the misfire occurred.

P0171------ system too lean bank#1
Po174------ system too lean bank#2
For these 2 codes, try cleaning the maf sensor (mass air flow), that is mounted in the big black hose that goes from the air filter housing to the throttle plate, if it is dirty, that will cause those 02 sensors to send a signal to the computor to lean the air fuel mixture. If cleaning it doesn't work, the sensors will probably need changing.
P0300---- Random/multiple cylinder misfire
P0316---- Cylinder misfire at start up---- first 100 revolutions.
On those 2 codes, you have to do some testing to find out why there is a misfire.
Possible causes:
dirty/malfunctioning injectors
weak coil pack
fowling spark plugs/wires
Low fuel pressure

Sounds like you have a vacuum leak for the lean code and the misfires. I don't see a 473 code in my manual, but have a 463. The 463 is for the fuel level sensor open or voltage high.

vw2000 (2.0)
Blinking engine lt. Poor performance-barely make it up a hill.
Mechanic said bad O2 sensor--Replaced--had same problem-
Used "ADVANCED AUTO" Diagnostic meter---FREE FREE FREE
Code read MISFIRE
Replaced COIL pack!!!!!!!!!
Returned to Advance auto to clear codes---
NO CHECK engine light --runs like new
Believe the COIL pack went bad causing the sensor to clog and go bad--Probably could have just cleaned it.
Cost $200 parts and free labor>LOTS of bad words,gerasy hands and good running car
HOPE THIS HELPS SOMEONE

po301 thru po306 all misfire codes cylinder 1-6 remove plugs and replace them..... set the plug gap first
i suggest u replace the wires also if they never been replaced all these misfire codes can set the others and one is for the oxygen sensor ( 02s or HO2S) CIRCUT MALFUNCTION do u know how to check wireing systems
do the tune up plugs (set gap) .052-.056 change the fuel filter also. clear the codes hows it run
this info is for 98 E-250 4.2Litre
what engine do u have 4.2L or 4.6L i know it is a v-6 by the codes