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Lou P.
Lou P., ASE Certified Technician
Category: Lexus
Satisfied Customers: 4805
Experience:  I Have knowledge in almost all car lines and can help with general questions and more!!!!!
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I have a 1997 Lexus ES300 that is having random misfires.

Customer Question

I have a 1997 Lexus ES300 that is having random misfires.
Submitted: 1 year ago.
Category: Lexus
Customer: replied 1 year ago.
Ok here is the long story. This is not my car and I am trying to help a friend. Now I am working on it.
First the misfire was 1,3,5. Compression is good.
He changed the fuel injectors, plugs, the three coils, coil wires, and o2 sensor.
I am not sure what else he may have changed.I drove it to my house and appears to run ok at higher RPM.
ideals roughHooked up my scanner and it showed misfire on 1,2 and 6.
I can not find a good diagram of which wires connect to which coils.
So I went and got another coil and replaced the one. Now the misfire has moved to other cylinders.So first I need to know the firing order to make sure the plug wires are connected correctly.I think it is 135 on fire wall side and 2,4,6 on the headlight side.
But I am not sure where the wires go.
Customer: replied 1 year ago.
If you do not wish to type a long message you can call me at(###) ###-####Jeremy Greene
Customer: replied 1 year ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Provide Diagrams, Manuals, or Instructions. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Lou P. replied 1 year ago.

Hello, so sorry for the delay, are you still needing assistance?

Customer: replied 1 year ago.
I did find that some of the wires were loose.
So I fixed that and now I am just getting a misfire on #6
I swapped the coils and spark plug, but still on 6.
Compression is consistent with the others.
Expert:  Lou P. replied 1 year ago.

ok, good deal so far, so do you have a stethoscope to listen to the injector? or check the injector plug or listen to the injector with a screwdriver to see if it is working?

Expert:  Lou P. replied 1 year ago.

you are doing no different then i would do, so far so good.

Customer: replied 1 year ago.
I can try. If not I could pull the rail off and swap injector 6 for injector 4. its at the front so its not that bad.
If I were to use a screw driver what should I hear?
Expert:  Lou P. replied 1 year ago.

well if you listen with your ear to the end of the screwdriver and the other end touching the injector you will hear the tap.tap.tap of the injector, and compare to other injectors.

Customer: replied 1 year ago.
Ok I am going to try that. I will be back in a few mins.
Expert:  Lou P. replied 1 year ago.

ok

Customer: replied 1 year ago.
Ok so here is the deal..... see if you can follow.1. injector sounds the same as the others.
2. I swapped the coil from # ***** and moved it to #2. Cleared the codes fired it up. Showed no codes ran ruff codes popped up. Misfire on 1,2 and 6.
3. Moved the coils back to the way they were and reset everything. Still ran ruff then code for misfire on #6.It is really weird if I move the coil from #6 to any other location those show misfire and still number 6.
I check voltage going to the coils and all have 12/14 volts.
Expert:  Lou P. replied 1 year ago.

ok , so when was the last time the car was filled with fuel? and where were the new parts purchased from?

Expert:  Lou P. replied 1 year ago.

your issue is above the ignition.

Expert:  Lou P. replied 1 year ago.

why moving the coil causes change is odd but having that kind of shift of misfires tells me it is something else that is affecting all cylinders and for some reason only a few are showing up. how did this all start?

Customer: replied 1 year ago.
New new parts I assume are junk......I think he bought them online.
I bought one new coil from advance auto parts made by intermotor, wires are ngk.
Fuel is a good question. Not sure on that. I have burned about 1/4 tank working on it.
I do have about 5 gallons of fresh fuel here, just bought today.....was going to mow the yard.
Expert:  Lou P. replied 1 year ago.

how are you going to mow the yard with a lexus?......... ah i get it, lol, kidding. ok so yes its something like mass, maf, tps, o2 sensor, fuel, something like that.

Customer: replied 1 year ago.
I also can give you some live data from the obd reader i have. It will do live data code def, emission status, and freeze frame (that freeze thing i cant seem to get to work.)
Expert:  Lou P. replied 1 year ago.

firing order fyi

Customer: replied 1 year ago.
Can you give me info on how to test these, like restiance or voltage? Sorry my spelling sucks
Expert:  Lou P. replied 1 year ago.

does it misfire at idle or when driving.?

Expert:  Lou P. replied 1 year ago.

and yes no worries, we are mechanics not English teachers :)

Customer: replied 1 year ago.
car starts right away idles rough but seems better and about 2k rpm.
weird at idle the car does not code even after 5-10 mins.
If you hold the idle at 2-2.5k rpm for 30 sec it codes. But seem to be running smoother
Expert:  Lou P. replied 1 year ago.

ok if runs smoother then spray around for air leaks while watching fuel trims if you scanner reads live data. spray the intake with brake cleaner or carb cleaner or a little water. if rpms change there is a leak.

Customer: replied 1 year ago.
Ok maybe I am over thinking this but I am not a real mechanic.
If the coils have 2 wired that send the voltage to the coil. Should both have 12/14 volts all them time?
I am not understanding how they get a signal that say #1 is firing, now #2.
Customer: replied 1 year ago.
I tested the two lead wired to the coils on 2 of the 3 and both wires have voltage all the time.
12.5, 13.3, 14.4, but never less than 12.
Expert:  Lou P. replied 1 year ago.

ok, so there are only 2 wires on the coil plugs?

Customer: replied 1 year ago.
two small wire plug into the coil to give it voltage.
Both are hot all the time.
Expert:  Lou P. replied 1 year ago.

ok i see there are only 2, so one wire gets battery voltage all the time, the crank sensor and cam sensor tell the ecm when to fire the coils .

Customer: replied 1 year ago.
with my tester I connected the ground to the battery, both wires are showing power all the time
Customer: replied 1 year ago.
If i do the same thing with a test light should it flash?
I assume because the coils operate 2 cylinders that the two
wire tell the primary and secondary coil when to fire?
Customer: replied 1 year ago.
Ok so it seems the more I let it run the more misfires happen.
I touched nothing but now it is misfiring on 1,2,4,and 6.
Customer: replied 1 year ago.
are you still there?
Expert:  Lou P. replied 1 year ago.

back now.

Expert:  Lou P. replied 1 year ago.

they may flash too fast for the test light or meter to catch it.

Expert:  Lou P. replied 1 year ago.

since there are only 2 wires the coils fire both cylinder at the same time. the coil and the wire attached to the coil. did you spray any thing around the engine to see if the rpms change?

Customer: replied 1 year ago.
I did but could not get anything to change.
I am wondering if maybe you were on to something with a sensor.
As I said above before I sprayed anything it started misfiring on 1,2,4, and 6.
I did meter the camshaft sensor and it appears to be ok.
Expert:  Lou P. replied 1 year ago.

is there a mass air flow sensor on this model?

Expert:  Lou P. replied 1 year ago.

i am also checking on some other info.

Expert:  Lou P. replied 1 year ago.

tap on the egr valve see if it changes the idle, it can be hanging open causing a internal vacuum leak.

Expert:  Lou P. replied 1 year ago.

also hook up a vacuum gauge to a vacuum line that has constant vacuum ,this engine appears to have adjustable valves. depending on the mileage the valves may need adjusting.

Expert:  Lou P. replied 1 year ago.

also i forgot to ask what kind of spark plugs were installed. ?

also you did not specify how the issues all started, did the misfires appear after recent work or did the misfires appear before the work?

this engine will run best with NGK plugs. also make sure all the ground wires are bolted on the intake and that there are no stragglers hanging around.

Expert:  Lou P. replied 1 year ago.

i have to leave for the night i will be back on early am tomorrow, ,let me know if you find anything, we can get this fixed up, well figure it out.

Customer: replied 1 year ago.
I have to work my real job tomorrow until 5.
Here are my thoughts.
It appears that there is no mech reason for the misfire.
It appears to move around. The more I let the car run the more misfires the computer sees.
I am wondering if a senson or something is not correctly sending data.
I am not getting any codes for that but I am not sure what would cause so many misfires.
When the guy first had the problem the code was misfire on 1,3,5 now its 1,2,4,and 6.
Feel free to send your thoughts my way and I will run through them tomorrow.
As I said i will not start work on it again until after 5 pm est.
Expert:  Lou P. replied 1 year ago.

ok so i need to know if your scan tool reads live data or just freeze frame, either way we need to check the map sensor voltage, and the coolant temp sensor readings. does it seem to run better or worse when the engine is cold? as much info as you can give me will help. it is definitely a sensor that is not reading correctly or something that is affecting the whole engine, sometimes so many misfires occur that the ecm cannot determine what cylinder is misfiring. also the fact that you swap a coil and the misfires change is still a clue something is off right there for sure.

Customer: replied 1 year ago.
It does live data. I will go collect it and send it over to you.
Also the ignition advance seems high. It says it is 25 degrees advanced at idle and about 40-50 at 2k rpm.
Give me 20 mins and I will get all the data over to you.
Customer: replied 1 year ago.
Ok here is what I have
Fuel sys 1- Open
Fuel sys 2- Open
Cal Load- 25.1%
Coolant -*****FTRM1 - 0%
LT FTRM1 - 14.6%
ST FTRM2 - 0%
LT FTRM2 - 3.9%
RPM - 988
Ign Advance - 29 degrees
IAT - 100 degrees
MAP - it moved back and forth from 0.75-0.80 lbs
Abslt TPS - 10.2
O2S11v - it moved back and forth from 0.055-0.060
O2S12V - it moved back and forth from 0.060-0.065
O2S21v - it moved back and forth from 0.020-0.025I/M
Misfire - OK
Fuel System Mon - OK
Comp Component - OKAlso now the misfires are 1,2,4,5, and 6.
Customer: replied 1 year ago.
I don't think the misfire moves just all of them code the longer it runs.
It does seem to run slightly better when the car is warm, but very little.
Expert:  Lou P. replied 1 year ago.

ok, see the LT FTRM1 compared to LT FTRM2, that is how much fuel the system is adding to compensate, the difference is huge, they should always be within a percent or 2 of each other not 11%. so keep watching that value and see how high it goes that is a good indication of a air leak internal or external, i am still checking to see if there is another value i am missing.

Expert:  Lou P. replied 1 year ago.

also you want the FUEL SYS 1 and 2 to show CLOSED, that means that the o2 sensors will take over the fuel trim , OPEN means the system is running a predefined mixture, so wait until it shows closed and also the temp is above 200. those will be some good readings for us, and instead of typing it out take a picture and upload here or i will send a link to a site you can drop files to.

Customer: replied 1 year ago.
opt out
Expert:  Lou P. replied 1 year ago.

ouch, ok, will do. :( wish you the best.,