lexusisgs

Hi there,
recently I got p 0300 code .very known missfire code.
first I was thinking spark plugs
second could b a coil.
well that missfire was happening only at cold start.
problem goes away after car is at operating temperature.
next guess was mass sensor located on cold air intake hose.

Brake cleaner will do but I got crc special mass sensor cleaner.
remove sensor from housing and from 10-11 inches spray the mini sensor wires.LET IT DRY ON AIR NO CLOTH USED.
I did it twice and put it back.
guess what code never come back , problem missfire solved for few bucks.
tested at cold start it was awsome.
low and hi speed outstanding .
super fast .
cheers.
☺☺☺☺☺

lexusisgs

If that not working in your case than replace sparkplugs and coils.
I am so happy with gs 450h as u can se from picture
over 300 000 km

lexusisgs

mobil one syntetic oil 5W30 all year around
brake pads TOVASTY ALL AROUND
COOLANT FROM dealership PINK
SPARKPLUGS DENSO WITH 3 ELECTRODES ON TOP
COILS FROM EBAY
SUSPENION KBM SHOCKS
LIFT AT BACK 2.5 INCH NO LIFTING KIT JUST COILS FROM SHELBY COBRA MUSTANG FORD,(YES IT WILL FIT )
DUAL EXSHAUST FROM IS250 AWD ,..(YES IT WILL FIT ..NO WELDING JUST C-LAMP USED)
LED ALL ARUND ,FROM EBUY.
TIRES 18 INCH MINERVA
TIRES 17 INCH WINTER WANLI FTER BLIZZAK ......BOTH SETS WITH OEM TPMS
HYBRID BATTERY REFRESHED WITH COUPLE CELLS FROM CAMRY 2009,
ENGINE ORIGINAL AS WELL AS THE TRANSSMISSION.
CONTROL ARMS OEM.
REAR WHEEL HUBBEARING HAS TO B OEM BECAUSE OF CENTER PIECE TO FAR FROM ABS SENSORS .
ABS SENSORS FROM EBAY ABOUT $30.00 PAIR.

MOD ON NAVI SYSTEM BY MARK L.
DVD MOD .GREAT SORROUND SOUND.

THAT IS WAY HOW TO TREAT CAR AND MAKE HIGH MILAGE.....
​​​​​​​CHEERS...

lexusisgs

ok new update .It was awhile without missfire now happened again P0300,P0304,P0305(no freeze frame on this one cylinder 5)
I have new spark plugs OEM all 6 DENSO iridium
I have checked injectors playing with selection PORT,DIRECT,or EATHER positions.every injector responded ok.
I have to try swap coils and put them on a different cylinders .
the Funny part car is still running fine just sometimes happened like that It cant be even noticed while driving must be some mini misfiring action here.
anybody had similar issue.

missfire happening randomly not just at cold start.It happened at 20 miles/hour ,40 miles/hour ,even on idle one time when car was warm.

alexchris1

Check my thread from page 2. Same problem From what i saw there has been allot of misfire issues on v6 petrol engines. GTR 's 350z, 370z, Porsche's flat 6 misfiring and most of them are a mystery.

Gs3500

Could be carbon buildup as well.

SILENTM

Put a borescope with mirror attachment down cylinder #5 spark plug opening and look at the cylinder walls for scoring also check the top of piston crown and intake valves for carbon build up

BinaryJay

Was this car ever serviced for the piston ring replacement? If not, then loose piston rings and carbon buildup is your problem. You can have the dealer perform a top engine clean, it won't be cheap.

lexusisgs

Thank you guys so much for reply,
I will make appointment at dealer for compression check first and also carbon build up check.
so far I was moving coils around to elimanate problem if coil is faulty and spark plugs and result was always same regardles of sparkplug or coil .Still same cylinder 4 and 5 missfireing.
After I did oil change 5w30 missfire didnt happened two days in row.Anyway I am going to see what dealer will say,wish me luck they are expensive.

lexusisgs

well this was educational experiance.
Went to the dealer and read code P0300,P0304,P0305,SOMETIMES P0301 AFTER THAT WE HAVE checked for compression and any vacum leak.Everything was ok.
Advise was that I have clean carbon deposit.So here we go---->3/8 rubber hose attached to the left side of the intake and downsize to 1/4 hose (like small casade) used Seafoam and some AC DELCO from GM solution.After that hose was attached to the right side of intake.
Car was put in maintance mode that was running all the time.(Hybrid disengaged in this case )
very small amount of the solution was sucked in.Turned off engine for about 5-10 min.Started again in maintance mode and FLOOR IT....lol that was the best part .Very hi RPM will produce so much white smoke that was unreal.(do not inhale that smoke )remove the 3/8 rubber hose and put plug on both sides of intake.PROBLEM SOLVED NO MORE MISSFIRING.
overview : carbon is like mini rock with so manny small pores and when u are at cold start fuel is not coming thrue so easy and we got misfire,however after warming up more fuel is coming and carbon rock become wet and let fuel to flow better so missfire will b gone temporary.You will notice more missfire at lower speed because demand for fuel at low speed is less and on the highway will be oposite.
That was mine explanation.
So me ,my self and I are very happy with results of carbon removal.Car running like brand new again.


P>S> will post soon picture of some stuff we have used here to get rid of missfire.

thank yo all for hlp.

SILENTM

bg products makes a 2 part kit also especially for direct injection. use a small bundle of zip ties to scrape and knock loose the carbon

lexusisgs

Here is some pics of precedure i have used to get rid of carbon deposit. Custom made hose by me
Here is location where hose need to be conectef
Close view of end cap hose that must be removed.
After cup has been removed attach custom made hose ....make sure it is tight fit.you can use small clamp if you want.
Start car on maintance mode and other end of hose put in sea foam can.it will slowly sucked.in solution.smoke will be hugh coming from tail pipe .that will be carbon burning out.
Stop the engine for about 10 min.and start again.it will be shaking and smoking and missfiring.i got all 300 codes on dash.P0300,P0302,P0305,....P0306
After engine settle down i did conect hose to this side and repeated same procedure.you can see small clamp i have add for tight fit ...no vacum leak.

lexusisgs

Now rwmove custom made hose , put back end cap and go on expressway to burn out leftover carbon.
Watch fot cat.convertor to not overheat it
If you do will trigfer P0420 code.
This process worked great for my cars .
Cheers

SILENTM

Be careful with this method as you can easily hydrolock the engine. Some of the solution will get stuck inside the intake manifold. This method is good for preventive maintenance after a good walnut blasting. It will just take off the top layer of carbon and eventually clog up the cats, leading to and more expensive repair. Not to discourage anyone, just a heads up

This was left to soak in berrymen chem-dip for a week

lexusisgs

I did this method on altima hybrid before and never got issues.
it has now on dash over 550 000 km and still runing.
i think this cleanup should be done every year or every 20 000 km .
beside that i dont think its good idea to leave seafom in gastank for extended period of time because it will eat gas lines.it is corosive but fot what i have used looks ok for now.
if anybody else know better way to clean carbon please post it her.
thank you.