Mohdbaj

I have been experiencing a check engine light. It all starts when I did a cold start the engine started to idling roughly till coolant temp reached a specific temperature. When I went to my mechanic he told me that I had misfire on cylinder 4,6 and random multiple misfire on all the cylinders. I replaced the spark plugs with denso OEM, changed air filters, replaced cylinders’ 4,6 coils, and cleaned the fuel injectors. Yet, I am still having the same problem. The last time I went to my mechanic, he told me that I probably need to replace the fuel injectors. Apparently, there are 16 fuel injectors, and he wants me to change the ones that are inside the engine. What do you guys think about this? Has anyone experienced something like that?
Thanks.

Benjam1n

Yikes that would be expensive. Did you try fuel injector cleaners like techron? Maybe you got some bad gas? If the engine smooths out when it warms up, I would put in some fuel system clean and do an italian tune up. Aka drive it hard and fast in low gear for half an hour or until you get pulled over. The manual mode shifter makes it a cinch. I've had misfire codes twice on my 08 460, both times new plugs immediately solved it. Maybe its a wiring issue? Good luck.

Tnguyen528

Hey I'm new here and I hope

Tnguyen528

Hey I'm new here and I hope someone can help me with an issue also. I have a 2007 ls460l and I too am having the same issues with the misfires. I have the misfire codes showing cylinders 4 and 8. I was told by my mechanic to change the valve gasket seal and I did. That didn't help. I found oil inside the plugs still so I went on to change the plugs, ignition coils, and the oil. I went as far as changing a new vvt solenoid and still misfire codes. I took everyone of the fuel injectors out and cleaned them cause I was told it could be carbon buildup bnb ut it still didn't help. I dont know what else to do cause I've done everything except get a new engine. Can someone help? Dont want to take it to the dealer and have them charge me an arm and a leg.

Anfanger

I would start with injector cleaner, Lukas works well and proven to fix misfire when caused by buildup.

When you took injectors out, did inspect all gaskets and o-rings? Misfire usually happens when one or two of two lower seals starts to leak and cause blow by. I believe, there was no need to change coils. You could have swapped coils with a properly working cylinder and rule coils out.

sdls

Random multiple misfire can be caused by a vacuum leak; ask for a smoke test to be performed to rule out a vacuum leak if possible

Anfanger

Wouldn't vacuum leak set off other codes?

sdls

sometimes but not all the time

Anfanger

I believe, the intake manifold gaskets can cause some intermittent vacuum problems. I have replaced mine so I don't have worry about it.

I had a very similar issue when the misfire code was set off during cold start. But once the engine gets warm, no misfire was registering (Techstream). In my case, the cause was injector blow-by.

sdls

What was your solution to the issue?

Anfanger

Lower injector seals needed to be replaced. And you can't replace it by yourself because it is made of PTFE and stretches out very easily rendering it unusable. There is a special SST designed for that.

At least, it fixed my issue. I am not sure if it is applicable in this case.

miket000

I didn't see you mention spark plug tube seals. If the oil your seeing is on top of the spark plug this might help.

I had the issue of oil getting on top of my plugs. There was a lot of oil in some cylinders. In some cases the oil was over the top of the spark plug. The spark plug tube seals were bad. After I sucked oil out with a 1/4" fish tank size thin wall tube. I then used paper towels to soak up the rest of the oil.

I installed new after market spark plug tubes. Which did NOT fix the issue. I did the same procedure again and used original lexus spark plug tube seals. It has been over a year now with no issues.

Does your car throw codes right away after swapping parts or does it drive fine for awhile?

Hamatron63

Did you ever figure out what was your problem? I'm having a similar issue. My car is currently at the dealership and they can't seem to figure out what the problem is either. Appreciate any input

sktn77a

iTrader: (2)

In general, after a couple of the cheapest fixes don't work on these cars, it's time to visit the dealer. "My mechanic says" can cost you quite a lot of money!

Tnguyen528

Ok so you really want to hear this? The problem I had with motor that I posted was never found. I did the whole dealership thing and they raped me for $3600. They couldn't figure it out and wanted another $4000 to dig into it deeper or should I say dig deeper into my pockets. Well I towed the car and brought it home. Found a motor online and did an engine swap at home. That was the solution to that problem but here's the kicker. I drove this engine for 6 months and again the exact same symptoms. Misfires in the same two cylinders. I changed out everything and when there was nothing left to change I took it to a local mechanic who said he might be able to fix it. He kept it for 7 months and I finally had to tell him he's not going to be able to fix it. Brought it home and my neighbor started researching and reading up and one morning he asked me if I checked and replaced yhe head gasket. I never did that and the other mechanics never did that either. I run and order one and the next day tore down the car and swapped out the gasket. Son of a ***** fired right up with no hesitation. Didnt believe what I was seeing so I slowly drove to the freeway and dam son of a ***** starts hauling *** like it was lightning or something. Went through 2 engines and every part and 2 mechanics from dealerships and to find out it was a $80 head gasket. Dam lexus guys didn't even know what the f@^$# they were doing. I hope this will help you out in any way. There are some other things you can try but if its the same cylinders over and over again the check your head gasket.