Car runs on 5 cylinders when it's cold (as if I leave it parked overnight and started up the next morning) but once warmed up it runs and act perfectly normal.

Check engine code: P1320 & P0306.

Parts I've replaced in an attempt to fix it:

- Replaced IACV (twice)
- Replaced the crankcase position sensor (REF). Near the oil filter.
- Cleaned TB
- Replaced all 6 spark plugs and coil packs.
- Moved the spark plug & coil pack on cylinder #6 to a different cylinder.
- Checked for air leaks/loose hose.

Nothing works. Again, the car runs perfectly fine once it has warmed up.

 

If plug is good and coil is good, then you have wiring problem. Look into that or have a shop look at it

 

Looking at the list of what you have done, you have ruled out a lot of things. The fuel injector seems to be the next thing to check/try.

 

It runs fine when the car warmed up, is injector an issue?

 

When a misfire goes away after the car warms up a clogged fuel injector could be the culprit. Three years ago I had the same problem with codes P1320 & P0304. I first tried swapping coils 4 and 2 but I still got code P0304. I then swapped fuel injectors 4 and 2 and then got code P0302.

I tried the easy route by throwing chevorn techron and then seafoam with tanks of premium gas. The cold misfire didn't stop but it went away quicker. I then disassembled all 6 fuel injectors and let them sit in acid for a few days. That solved the problem. I also threw on new mesh filters, pintle caps, and o-rings.

 

How do I test the injector?

 

The injector is both mechanical and electrical. It uses an electric magnet (solenoid) to open and close the opening for the gasoline. To test it electrically, unplug the wire harness and measure the resistance of the solenoid. Compare that reading to a couple of other fuel injectors to see what the reading should be. All the fuel injectors should be within a few ohms of each other. A bad fuel injector will have a higher resistance reading.

The test for the mechanical part is somewhat educated guess work. You have the fuel rail off the engine but still hooked up to the fuel pump. Hold a cup or some container under the injector and crank the engine for 3 seconds. Watch the fuel spraying out that it is an even mist and that the quantity of fuel is comparable to the other injectors.

Or swap the injector with another cylinder and see what happens.

 

I Never touched fuel injectors before, any special precautions? Since it's a #6 fuel injector, it looks pretty quick and easy to remove and reinstall...?

 

It should't be that hard. Once you take the 2 screws out, the fuel injector should pull out using a slight twisting motion. There are 2 o-rings on a fuel injector that you should get before you do this. The ones currently on the injector are old and probably won't stand up to being pulled out and re-inserted. If they don't break when you remove the injector, they probably will when you put it in and you will have a nasty fuel leak. If you are going to swap injectors, get the o-rings for both injectors. and coat the o-rings with vasoline or something when you go to put the injector in.

 

Just got done doing the compression test on a hot engine.
Cylinder #6 = 180 psi
Cylinder #4 = 170 psi
Cylinder #2 = 170 psi

Cylinder #1 = 180 psi
Cylinder #3 = 185 psi
Cylinder #5 = 195 psi ???


Should I now wait for the engine to get cold and do the compression test again?

Spark plugs looks fine to me, what do you guys think?

 

Doing a cold engine compression test probably won't make any difference. If you had a problem with rings or valves or whatever, it would show whether the engine was hot or cold. The plugs look good to me. The engine runs good when warm so the plug should look good.

Compression should be 185 psi with a minimum of 140 psi. Why # 5 is at 195, I don't know. The only thing I can think of would be deposits like carbon building up. Does the spark plug from that cylinder look like the others?

 

Before taking anything apart......try this;

http://forums.maxima.org/general-max...troke-oil.html


For those of us with all working injectors, like me, we 've noticed a significant quieting down of the engine once using this TCW3 stuff. It may help un-stick your injector.