I own this car for allmost 2 years and all this time I can't fix this misfire.

Actron 9145 allways shows 0300 code and misfire on #5.

1. Spark plugs are new TR 55 V pover
2. Wires new. Belden Premium
3. Coils were swapped.
4. ICM was swapped.
5 Fuel injectors were swapped.
6. ICM and PCM grounds were cleaned.
7. PCM was swapped for testing purpose too.
8. LIM gasket new.

There is fuel to be burned and there is spark to burn it.

Any idea where to look?

Thanks in advance.

Do a compression test next.

#5 is VERY susceptible to shorting through the dipstick tube. Make sure that wire touches NOTHING but the plug. Wire loom it if necessary, but knowing compression of the 1, 3, and 5 (three easiest to do) would be good to know.

Wire isn't touching anything.
I checked it already.

Ok. Compression next.
As soon as I have result ,I will post it here.

Thanks for replying.

Regards

I didn't check compression yet, but another question has arrised.

When in overdrive and I kick gas pedal allmost to WOT I have bad detonation/knocking and engine like chocking instead of accelerate.
Well, I understand it might be related to this recent misfire,but when I bought this car misfire was here ,but I didn't have detonation.

Any idea where to look and what to check? No other codes besides 0300 (misfire) is recorded.

Thanks

Does that plug look any differnt from the others? What about deposits? Anyone think he could have carbon buildup? Let'* let others give opinions on that but perhaps seafoam will help.

Last time I removed sparkplugs ,#5 has black deposit on comparing to other were brown.
Looked like running rich. I remember some time ago when there was no detonation and I checked sparkplugs #5 wasn't much different than other plugs.

I might try to make pictures of all plugs tomorrow and post it here.

I changed my O2 sensor some months ago and when this detonation started I put the old one back to check if it'* not O2.
Recently put the new one back,but old one had white tip like running lean.

O2 is AC Delco by the way. I will make a picture of it too.

the seafoam couldn't hurt... but do it before you replace the 02

I've never done it before.
Is there any info or link to info how to do it and what else is required after- oil change,
change of anything else or car change

Honestly,this is the first car I have constant problem with.
As soon as you fix one thing,another just pop up.

I'm not mentioning thing like coolant level light (I know,change sensor,because coolant is OK), lamp monitor shows brake and tail lamp fault (yes,clean everything. Lightbulbs are perfectly fine) Security light is allways ON when driving (Yes .I checked trunk lid,it'* not there,probably one of the doors sensors) .


I understand it'* an old car but I remember having Crown Victoria with 170000 miles amnd I drove it to 320000 and only one thing was changed related to ignition.Don't remember exactly right now.
I allways wanted Bonneville,but this is way too much.
It'* constant repair cycle.

Well,just venting it out.

EDIT:

I forgot to mention air mix actuator needs to be replaced and master cylinder is leaking too.
Just full package to enjoy.

I had a isolated misfire and low and behold it was not the injector or spark plug or even coil.
It was the hot wire leading into the injector itsead, just wore out from the inside, plus being the closest to the EGR valve didn't help.
To test take off plug and test the pink side to another pink plug for continuity with a multimeter (test a couple a couple times-mine was failing intermitently). To replace I had some extra injector plugs from a engine swap, but take off bad pink wire from the inside of plug and route new one to the open connection (on mine its centrally located in the harness by EGR valve) not hard to back track. When I say its open connection you have to solder new wire to other 5 wires and hot leading to injector teriminal (that goes to inside of pass fuse panel).