I have a 2002 RX300 with about 210,000 miles.

I took a trip from Los Angeles to Bend Oregon about 6 months ago. Midway through the trip I get the check engine, Trac off, etc. lights. I drive on without issue. I leave the car with my son in Bend. He eventually gets the codes checked and they are PO171 and PO174. My son being my son, he does nothing more.

About a week ago, we make the trip back to Los Angeles. Early into the trip, I notice my RPMs are pretty high (4,000 at 65mph). We drive on because there is nothing else I can do. We stop after about 3 hours for some lunch. When I fire the car back up, the RPMs are fine until we hit Sacramento rush hour about four hours later. The RPMs jump again after we get back to cruising speed. We stop after about an hour, and when I fire her back up the RPMs are fine once again.

I read the codes when we get back to LA. They are still PO171 and PO 174, but now I'm reading PO330 as well. PO330 (the knock sensors) is consistent with what I've read about my high RPM experience.

Although I'm pretty handy, changing out the knock sensor scares me. So, I'm going to take it to the shop. But before I do, I figure I'll do the spark plug replacement which I had been putting off (I have no idea how long it has been other than it has been very long). I pull the three plugs in front. They are in pretty bad shape; particularly the one to the furthest left facing the engine (the coil is pretty badly discolored).

I start the car up, figuring I'll change the back three the next day (I get to the one furthest to the right, but I'm having difficulty disconnecting the PCV pipe per Lexmex's instructions). The check engine light, Trac off, etc. do not come on, and they have yet to come back on. The car idles at about 1250 rpm when it starts, but settles down to around 500 rpm at idle after driving around for a bit. I haven't been on the freeway, but the rpms seem ok.

I'm assuming that this is too good to be true. Am I right?

Also any thoughts on disconnecting the PCV pipe would be appreciated. I'm scared to death I won't be able to get it back on.

 

very possible the p0171 and p0174 lean codes can be the result of a spark plug change. If plugs aren't torqued to spec, they can back out. The coil packs have to work harder and may burn out just trying to ignite the air/fuel mixture.

As far as disconnecting the pcv pipe, pull off the end connected to the underside of the intake manifold first. The end on the pcv itself usually gets hard due to exposure to heat.

 

Thanks. That pipe just doesn't want to give. But the real issue for me is the connector to the coil. They are extremely difficult to remove even on the easy three up front. it's hard to get any leverage on the middle plug in the back. If I could remove the connector, this would be a walk in the park.

 

The pipe has just hardened over time and heat exposure. Even when you get it off, it would not seal back as the flex is gone. I would buy a new pipe and PCV valve and grommet and replace all three.

Coil packs and down hole tubes will require patience and small sideways movements will eventually break them free.

Salim

 

if needed use the widest flat head blade screwdriver you can find. Depress the clip with one hand and use a twisting motion with the screwdriver placed between the edge of the clip and coil.

The pvc pipe is nothing special if you are not close to the Lexus parts counter. use oil resistant hose...transmission/power steering hose works well, or silicone vac hose. Use the nipple of the pcv valve for size reference.

 

Guys, thanks for your help. I finally managed to get the last two clips off. But for those clips this diy would be cake.