RC12ECC is on the label stuck to my firewall, Google it and Champion copper plugs comes up first. Haynes manual states "Champion plugs", thats what I'm using.

There was a recall for adding the heat shield on the intake, it's there on mine. I think it was for debris building up and a possibility of a fire.

I think if you have a head with a '99 date of manufacture, your in good shape.

Earlier tooling and all.

 

date: 2-00 160K miles, no crack (so far)

 

Your fan comes on at 223 degrees. The gauge on the dash isn't accurate enough to tell this. "About 210 degrees" is somewhere in the 190-220 degree range.

 

Idk why but my 00 electric fan comes on below 210, I've confirmed it with a OBD2 scanner. It'll cycle on if I'm idling for a long time (even if the temps don't rise at all) and then turn off, repeat. I had to replace the pcm in my xj and it still does it.

 

That is odd. Are your XJs (jp and Ralph) CA or Federal emissions? jp, are you sure you had A/C turned off when you were testing? I've confirmed my '00 is 223 degrees with OBDII, just as everyone has stated here. Mine is federal emissions.

 

Mine is a CA Emissions. I remembered that I have an '01 Service Manual, mine is an '00, and it says exactly what you said. Comes on at 223 degrees. I never checked the live data with my scanner when the fan comes on but have otherwise. The reading my scanner says is pretty much in line with what the gauge says. But I figure both scanner and gauge are getting their info from the computer. Thinking like you said gauge is just not accurate enough. One day I will try to remember to check with my scanner.

 

 

You running the heat shield on top of the intake manifold? Knock on wood but heat soak/misfire issues are one problem I have never had with my CA Emissions '00. At least not that I have ever noticed. I had a crappy heat shield on her when I first got her. Replace it with a new one when I did the 4 hole injectors upgrade. She had Champion 438's in there when I bought her. Replaced with the same. Boy were those in bad shape when I did do that. Sometimes I wonder why I don't have these issues.

 

how do you like the 4 hole injector upgrade? does it smooth out the ol 4.0 THAT much? looking into this in the spring

 

Realize this is the butt dyno talking. Also realize that I bought brand new 4 hole injectors. Idle seems smoother, I want to say the pick up is better, and even going about 70 MPH with a little tap of the skinny pedal I can get a little rise out of the front end. Also I get about 22 MPG on my longer highway trips. But I also replace the fuel rail, all 4 O2 sensors (CA Emissions '00), she has fresh plugs, etc. Also realize, as people have stated before (and I kinda agree), it is not the 4 hole injectors it is the fact that you have fresh injectors. Not grungy ones with 175K on them.

 

Aha!
This explains why we have no precats on our 2000 Freedom. It would then be federal emission equipped.
There are only two plugs in the bungs above the downpipe collector and they are above the downpipes.

What it does not explain is the recent p0135 code indicating a high voltage on the O2 at the bank 1, sensor 1 location.
everything I have read suggests the pre cat O2 sensor on the forward downpipe.
hmmmm

I guess we will swap the 1st one pre main cat. See what is left.

If this needs moved please do so. I found it searching for pre cat o2 and am glad I ran across it.