OliverLS

Before you read this I would like to make clear that I am not from Florida, I am from Panama (the country), so if you find some words that you don´t understand I´m sorry, my native language is spanish.

Hello everyone, you might know me from the ATF mixed with coolant thread so you probably know im kind of a dumbass . Im making this thread to see if someone might have an answer to my problem (I´ve tried to diagnose the problem myself, I´m 20 so I barely know anything), my 2004 LS430 is misfiring BAD, the check engine light keeps blinking. I'll tell you what I have done and in order.

First, I connected the car to Techstream and it gave me some codes, P0031, P0172, P0175, P0300, P0301, P0303, P0305, P0307. Then I disconnected the battery, and swapped the coil packs form one bank to the other (7 to 8, 5 to 6, and on and on) also, the spark plugs were changed last year they were bought on amazon, they said they were Denso, the box said Denso also (A mechanic did it, but he's honest).

When I swapped the coil packs I noticed an EVAP Hose was broken completely (I´m not sure if it was broken a long time ago or just recently, TBH the car has always smelled like gas), the one that connects to the VSV valve, so I did what anyone with a 16 year old car would do, break it trying to get it off and proceding to break every other hose (i´ll attach images of everything I did).

I tried to glue the valve again but it broke again, so I grabbed a piece of hose and connected the metal tube that directs the gas fumes to the VSV valve and directed it straight to the floor and plugged the metal piece that is connected to the intake so no air would escape from it. (This is a temporary fix until I can get the VSV Valve, i´ll attach pictures so you can laugh at me) Please tell me if you think buying this valve is important, in my country we don´t care for emissions.

The car was disconnected from the battery for around 3 or 4 days, then, I connected it back again, the car ran fantastic, had plenty of power. I drove it for one whole day (the 24th of december) the check engine light came on that same day
but just for P0031, still, drove fantastic, checked with techstream and it wasn´t misfiring.

I haven´t driven the car since the 24th but I have started it everyday, but today the light started flashing and it started misfiring again, I placed a screwdriver on the injectors and heard the same clicking sound on all 8 cylinders. The car has these codes P0031, P0300, P0303, P0305, P0307, no more codes.

Also, that O2 sensor my dad has changed it 2 times already, that code has always been there but the car wasn´t misfiring that bad, I only remember it misfiring this bad a few years ago but I don´t remember if it fixed itself or something changed, we´ve had this car since 2012, so yes, that code has been there for 8 years straight (world record maybe?).

I am a very cheap guy, I don´t care for check engine lights, I just want the car to not misfire so bad, any redneck or ghetto fix is fine for me, I´m like a redneck latino. Tomorrow I´ll buy I multimeter and check the resistance of everything that might be kinda suspicious.

THANKS FOR TAKING THE TIME TO READ THIS!!






The broken hose, I attatched another hose and pointed it to the floor to keep the fumes away from the engine bay

The hose that replaced the broken one and directed to the floor

The new hose pointing to the floor

The plugged valve, I don´t think any air is escaping.

Aus430

So let's start with 1 thing at a time.

I assuming you have patched or replaced all the cracked hoses. So no air leaks. I'm also assuming you brake booster is working (ie not heavy.) If they break you get a massive air leak in to the intake which can appear as a misfire. If you suspect this is possibly the cause then plug that vacuum hose to confirm.

1. What are your long term fuel trims for each bank?

2. When you swapped the coils, did the misfires stay in the same spot?
3. Have you moved the plugs? If so did the misfire move cylinder?

if the miss moved then you know it's ignition
if the miss didn't move its probably not ignition

Then:
check the connectors to the variable valve solenoids. Possibly even see how they respond to the solenoid test in tech stream. A broken vvt solenoid can mimmick a misfire.

if its not that you are left with fuel or compression.
check the connectors on injectors.
possibly swap injectors around if you have good oring handy. They will likely be hard and brittle with age unless recently replaced..

See how you go.

OliverLS

Thanks for replying.

1. The only long term fuel trims I have is from the car running for about 5 hours (the car had no power before so the computer reset). For Bank 1 its -20.4% and for Bank 2 it´s -23.5%. The short term (at the time I took the picture at idle) were for Bank 1 -20.4% and for Bank 2 +10.1%.

2. Yes, when I swapped the coils the misfire stayed in the same cylinder.

3. I have yet to do that, I'll do that next.

ls430w140

Is your engine coolant temperature sensor fine?

when u have a chance , check one of my threads to make a decision about VSV.

Good luck!

YODAONE

Is this a temporary repair?

Worth replacing with correct factory hoses and hose clamps..engine will.perform better and .not expensive parts.

Have your mechanic check your Oil Control Valves.(OCV)

Aus430

3. Cool after swapping plugs around if it is still persisting...

4. Run the activity test on the vvt solenoids to see if they are working in techstream

if its not either of those then let's isolate the cause with the ltft.
20 & -23 ltft means it is pulling fuel from the mix. Ie computer thinks there is more air there than there really is - therefore pulling fuel to get back to stoichiometric mix according to o2 sensor reading.

Usually the cause is a dirty maf sensor/or dodgy maf sensor giving computer wrong value of air volume to begin with.

Potentially a dodgy o2 sensor reading giving computer incorrect reading

Or possibly there really is too much fuel than it thinks should be there caused by non standard injectors, faulty fuel pressure regulator allowing too much pressure in, additional fuel source, etc

Or possibly because of the misfire the o2 sensors are reading rich with the unburned fuel in the exhaust.

The ltfts in these cars change about quite quickly in the 3uz as the computer is constantly tuning itself based in what is going on.

For a more accurate diagnosis before fiddling about just changing parts, can you confirm:

is the ltft same across the rev range?
Or just idle?

can you graph about 1 minutes worth of data of the following?:
both bank ltfts,
maf,
throttle position
revs
and both banks o2

Recorded from idle to 3000rpm. Engine at operating temp.


Again only do this after first changing the plugs around to see if the miss moves and if that wasn't it, then checking the correct operation of the vvt solenoids in techstream.

OliverLS

I´m not sure how to check that, I think it might be alright, but when I start the car even when its cold (Here in Panama cold is 77°F) the fan starts running at normal speed, but the car warms up to the correct temperature.

OliverLS

Thanks for replying, I'll be sure to check that.

OliverLS

As soon as I check that I'll post the results, thanks!

OliverLS

I have just realized that I'm not replying to everyone individually, I´m sorry, I´m new to this page, the next posts I'll be sure to quote everyone.

OliverLS

Hi, I did a resistance test at 30° celcius or 86 °F.

The resistance was around 1770 ohms.

Aus430

Any luck swapping the spark plugs?

OliverLS

I just changed the spark plugs, I didn't had much time so I only swapped the SP from cylinder 3 to cylinder 1. Here´s how they looked.

The mehcanic didn't change the spark plugs, I know this because I bought platinum SP, and those are Iridium. I know I should buy iridium next time and change them myself. The car has 88k miles, is 16 years old. I know that 88k miles isn't when they are supposed to be changed but where I live I do a lot of city driving, a lot of bumper to bumper traffic (I live in Panama the country), that car I would guess that the equivalent to a car living in America has to be the mileage converted to kilometers, I'd say that the equivalent has to be around 140k miles. Litteraly where I'm from, if the traffic is too bad, just to move 2 miles it takes like 15 minutes.

I'm not that good at reading spark plugs, how do you think they look? Should I replace them? I didn´t see any cracks on them.

Cylinder 1

Cylinder 1

Cylinder 1

Cylinder 1

Cylinder 3 (misfiring)

Cylinder 3 (misfiring)

Aus430

I just spent a bit of time rereading the first post and translating the codes into words. Ignore my previous comments as I missed a couple of clues.

The codes in words from google (my comments)

P0031 - o2s1 heater circuit low voltage (odd where is that voktage going)
P0172 - rich bank 1 (computer thinks there is too much fuel)
P0175 - rich bank 2 (computer thinks its rich)
P0300, - random missfires
P0301 - miss cylinder number 1
P0303 - miss number 3
P0305 - miss number 5
P0307 - miss number 7

So the computer will be trying to pull as much fuel as possible from bank 1 to bring it back to its ideal air fuel mix - until it hit maximum threshold it can as programmed and throws a check engine.

However both banks are running negative 20 ltft

"The car was disconnected from the battery for around 3 or 4 days, then, I connected it back again, the car ran fantastic, had plenty of power"

Computer reset back to base tune - effectively ignoring the o2 sensors as it calibrates itself. My car runs super smooth for first 30 minutes after a reset. Some of the codes/symptoms take longer than others to trigger/return. Also means plugs and coils are ok.

sounds like it is leaning itself out to point of misfiring on basis of a false rich reading. Although there is a bank 2 code there

I notice the o2s1 on bank 1 reads 1.27v! Yet the sensor 2 is at 0.03v which is very lean. Impossible for a catalytic converter to remove that much fuel.....

I've never seen a functioning o2 sensor read more than 0.95v. Sounds very much like a faulty o2 sensor as I'm pretty sure they are designed not to go above 1v. Ever. Regardless of how much fuel really is there. That, or somehow extra voltage is getting into the circuit on the way to the computer somehow through damaged/altered wiring.

"Also, that O2 sensor my dad has changed it 2 times already, that code has always been there but the car wasn´t misfiring that bad, I only remember it misfiring this bad a few years ago but I don´t remember if it fixed itself or something changed, we´ve had this car since 2012, so yes, that code has been there for 8 years straight (world record maybe?)."

Which code has been there for 8 years?
Which o2 sensor was put in? Denso? Or another brand?
Was the wiring touched? Checked?
if a code keeps coming back, it is likely something is wrong that is potentially contaminating the o2 sensor or there is a wiring problem between o2 and computer.

At this stage, before putting in a new O2, is there any chance of graph/charting the following sensor readings after computer reset (would be better to see sensor readings on base tune when everything is running smoothly)?

all 4 o2 sensors
the maf
Throttle position sensor
rpm
Speed
engine temp
Ltft b1
Ltft b2

About 15-30 minute drive should be enough to see sensor readings and computer behaviour as engine goes from cold to hot and computer start tuning itself from base.
Would be good to see the wave forms in separate charts.

Alternatively post the data file from techstream here and I'll take a look.

Striker223

Plugs look rich. You seriously need to just go over ALL the vacuum lines and put them exactly where they need to be and replace or clean the MAF sensor and make sure there are no leaks anywhere on the intake tract and finally replace the O2 sensors with factory ones

Check your injectors to make sure they are not sticking open