AlbertG

couple of months ago I have driving down the high way and a ton of light popped up on the dash.
CEL tracking VSC) After another 50 miles it developed a miss. Next morning the miss went away and it but all the lights were still on. Auto zone said misfire so I figured I need to change plugs(65k on the motor) well 100 miles into coming home the mis fire comes back. and we make it home.
next day same thing.....

I change the plugs.... disconnect the computer and it was good for a couple hundred miles and BAM!! it starts all over. CEL on... I noticed if I stay city driving it doesn't get to the miss fire point. but if I do any kind of highway driving it'll eventually develop a miss.

I check it again and it showed 2 and 4 mis fire, I picked up 3 coils put them all on the front. It ran good for 350 miles and bam here it is again.

Last Sunday I started up the car and it just started misfiring at idle. well I went to check it at autozone coz it was really bad. and it had 4 cylinders misfiring total.

well in the mean time getting it checked the light were on it wouldn't start. so I just bought a battery. (it had been having battery issues over the last couple months) I don't want wifey to be stranded somewhere with the baby.

I'm new to these news lexus's.. Ive had 2 Is 300's and my daughter has a gs 300.

Do I need to use a specific spark plug for the 350?
would the dying battery contribute to this?




Oh... and I did find the air box was not closed properly by the oil change company wifey uses. so I thought that was an issue but it cam one at the 350 mile mark.




Any ideas on what else to try..

TIA

12jimmyjam

It definitely uses iridium plugs only. The mass airflow sensor sometimes needs cleaned too. But if you put the wrong plugs in, I'd put my money on that.

AlbertG

It was doing it before I did the plugs. that's why I changed them I'll look today to see what I have in there.

chuyrobles

What is/are the OBD codes?
Are the same cylinders misfiring? Did you swap the 'bad' coils around to see if the misfire follows them?

Based on an IS300 driver with similar problem, you may have faulty/dirty injectors.

Here is list of code P0300 - Random Cylinder Misfire Condition:
- Faulty spark plug (s)
- Faulty ignition coil (s)
- Clogged or faulty fuel injector (s)
- Intake air leak
- Fuel injectors harness is open or shorted
- Fuel Injectors circuit poor electrical connection
- Ignition coils harness is open or shorted
- Ignition coils circuit poor electrical connection
- Insufficient cylinders compression
- Incorrect fuel pressure

Read more: http://engine-codes.com/p0300_lexus.html#ixzz3heUhqUTp

AlbertG

Did you swap the 'bad' coils around to see if the misfire ...
Thats what im doing today.

Plugs are iridium... but i was.told not.to gap them(which i did so i bought a new set to install

AlbertG

Changed with new plugs coz I was told not to gap Iridium plugs.
Cleaned the air meter as well.
swapped the coils from the from to the back.

after 10 miles of highway driving the Misfire comes back.
turned the car off for less than a min. everything cleared..... no dash light on.

drove back home after 9 miles of highway driving..... misfire.
this time I get home and disconnect and reconnect the #6 coil and the misfire goes away....

When ever I have disconnected any of the coils in the front it takes away the misfire as soon as I reconnect it.

craig72

This may sound odd, but check your gas cap.
I had the exact same issue on my 07 ES350 a couple years back. Started it one morning and it ran like complete crap. Check Engine light, VSC disabled. When I checked the codes, it reported misfire on a couple cylinders. Turns out the seal on my cap had gone bad. Its even listed in the manual as an item to replace during service (although I cannot remember the interval). I was able to REALLY crank mine down until my new cap arrived, and that got me through it.

AlbertG

Hey its worth a try....
I was just thinking about it today..... It seems like it has been this way ever since the NEW gas station(mobile) opened up right by my house. Maybe the car is not up to par... so I thought since it seemd to be happening at highway speeds it might be picking up some pinging due to the gas.
I'll try your idea first then start using other gas for a while to see if that helps

jkayca

Bad gas was my initial thought. The misfiring sounded so random and what diagnostic work you have already done seems to rule out the plugs and coils. Gas cap is an interesting idea although I would have thought you would have gotten the code for gas tank pressurization problem. Worth a shot though since it's an easy and inexpensive fix.

If all that fails my next thought would be the wiring harness for the coil packs. This is getting into an expensive area though so you might want to have the car properly diagnosed at the dealer rather than throw parts at it.

AlbertG

I'm trying to rule out each one at a time. Of course the dealer is the last resort.

The gas cap is a simply cheap attempt so I don't mind giving it a shot.

I'll try the cap first on this tank then put some better gas in the car after this tank is out.

I'll probably run some fuel cleaner(seafoam) just in case there is any build up.


It'll be the weekend before I get back to it. I'll be traveling for work the rest of the week.

jagtoes

Sounds like you are shooting in the dark and just throwing money into the car. Go back to square 1 and identify all of the codes that you have. Usually the first code triggered starts the other codes . Unfortunately you have gone through a lot of replacements and still not resolved the issue. Save your money and take it to a professional to diagnose and then if you want to fix do so or let them fix it. Good luck

AlbertG

The codes I got were miss fire on the 2 4 cylinder.

jagtoes

A misfire code almost all of the time means a bad coil. The initial verification would be to swap one of the other good coils and see if the problem moves. I believe a dealer would plug into your OBDII port and with the engine running verify the coil voltage. How many miles were on the spark plug and what was it's color read when removed. Unless you are around 75-100K miles a plug should not fail.

AlbertG

Less----65k.
I haven't touched the car.. I traveled for work and got sick. just getting back to feeling ok enough to do anything productive.

AlbertG

It's been a while since I posted. I had been busy with work and other projects.
I finally got back to working on this. All this time it still has the miss fire issue.

I had replaced 3 coils and still the same issue. then swapped them to the back same issue on cyl. 2 & 4
So next was swapping the injectors to see what happens.
-Same issue (2 & 4)
Went ahead and swapped back in the all the original coils back into the car. BAM RUNNING FINE!
Got about 50 miles on it so far... I put 30 of those where highway miles. There was a point where I was waiting on some one and it idled about 20 minutes.
As of lately the miss fire would always be there I could get it to go away even with disconnecting the battery.

What I did notice was the bottom of the #4 coil had oil residue on it and also had also some oil in the spark plug hole. Even the plug was wet with oil.( the top side of the plug- not the firing side) My guess is it was shorting out on the oil.

Question is how is the oil getting in there? (valve cover gasket)

Now to wait and see.....