So I have a 2000 ls400 with 105,000 and I'm wondering if you guys can help me out with the problem I'm having . I took my car into a mechanic because of the following codes p0300, p0302 p0306 p0308 and an faulty o2 sensor code on bank 2 all along with a vsc off message . He checked the coils and they all checked out . Replaced all the injector seals and replaced two injectors that are on there way out. Did a leak down test and all cylinders have over 100 psi in each cylinder. The missfire codes went away for all except p0308 he suggests that something is wrong with the head and the engine needs to be replaced . He is suggesting swapping the engine . I feel like this maybe drastic, is there anything else that could cause a missfire besides ignition and fuel. Could it be a bad/dirty ocv without a vvt code being thrown?

I know this might be lengthy but any help is appreciated

 

Have you already replaced the capacitors in the ECU? I know that can cause weird ghost issues with no explanation when they leak

 

I'd rather think it's an off timing issue. A skipped timing belt or a failed OCV must be there. I don't think it's caused by the ECU capacitors.

 

Can the ocv valve fail without throwing a vvt code?

 

Yes, it can.
A mechanical failure can't be detected by the ECU. In stead, random misfires are detected.

 

absolutely it can! happened on my 98. Mine would misfire all on one bank (1,3,5,7 or 2,4,6,8)

 

And depending on the type of leak down tester, not many auto tec's really know how to use them correctly.
And then there can be crappy crank and cam sensors too, as well as an intermittent electrical connector or even a bad ground.
If engineered right there could be code for a slipped belt it would be easy to do. Oh and what about the high t wires and normal ignition stuff like spark plugs etc.

 

So ocv's have been changed with no luck at all. At idle the car is still rough and low. Is this something that might get better if I drive it. Also now the only pending codes are for missfire on cylinder 1, 4, and 8.

 

did you unplug your negative battery terminal for 15 minutes or so ?

 

Humor us and swap coil 2 with coil 8, clear the codes.
Did the misfire move to #2?

Also get the actual cylinder pressures. >100 doesn't say much. I dont know this engine but 150 to 170 is more likely even at 100k.

 

I moved the coils around and the misfires stay at the same cylinder. I'll give the mechanic a call on Tuesday and get those cylinder pressure numbers. If it helps I think the previous owners might have overheated the engine since the thermostat is missing from the housing. Would it be possible for the misfires to come from that?

 

Hmm I didn't do that but I resest the cel with my scanner . Should be the same thing right?

 

Have you checked the belt timing?

 

Whaaaa?
Its a chain. No timing belt and even if it were, it would impact more than one cylinder.

So what came of this?

 

Check the plug on that cylinder for damage.