Wife's 2000 RX300 @98k miles; drove back from her office 4 miles away and the CEL started flashing in mid way; made it home but the engine appeared sluggish. I open the hood and let the engine idle: a little rough and can see vibration of the engine; the engine idles at just a hair over 500 rpm while it used to be at around 750 rpm in normal conditions. The CEL has not registered a stable ON and continues flashing.

Need guidance about how to start narrowing down the causes and failure components.

 

Get the CEL code(s).

I am guessing you have a bad ignition coil. The misfire code is P030X, where X is the misfiring cylinder, or P0300 which is general misfire. Cylinders 2,4, and 6 are facing the front of the car in that order from left to right as you face the engine. 1,3, and 5 are the rear ones. Hopefully it is not one of those rear ones as they can be tough to remove. I have done them, but the fronts are a piece of cake.

 

What does it mean if the (check engine) light is blinking?"If the light is blinking, a severe engine problem such as a catalyst-damaging misfire is occurring and should be addressed as soon as possible. You can still drive safely, but should minimize your time on the road. Try not to drive the vehicle at high speed or with excess weight (such as towing or carrying heavy equipment). Like Lexmus said - go any nearest parts store and let them read error codes via OBD2 port.

 

Thanks for sharing the insights.

The read is Code P0301. I guess that is my bad luck, with Cylinder 1 in the rear. The #1 coil gone bad, not the spark plug, or both?

What is the part #s for the coil and spark plug?

 

It is 99% likely it is the ignition coil vs the spark plug.

I would use a Denso 673-1301. I bought mine from Amazon for about $56. But if you can't find that locally and you need the car ASAP just get one at the auto parts store.
OEM is 90080-19016 but is $120 from the dealer.

#1 and #5 are easier than #3. which is in the center under the intake manifold. #1 isn't that bad, but will take a little time. Practice taking one of the front ones off first so you get the feel of the removing the connector plug, removing the bolt, and pulling the coil out before you go after #1.

 

Thanks for the advice. Just ordered a Denso 673-1301 part on Amazon, which is to arrive on Monday via the Prime shipping program.

I searched on the Forum for a DIY post on replacing ignition coils but could not find one with photos. If there has been one somewhere, please provide a pointer.

 

Check out the spark plug DIY. The ignition coils are part of that

https://www.clublexus.com/forums/rx-...-patience.html

 

Got it. Thank you very much.

 

Just do ALL the plugs. At 98k miles it is time. For the amount of work involved in removing the intake manifold, I would just replace all the plugs while I'm in there.

 

You do not need to remove the intake manifold to do the plugs.

 

Finally good weather came and I was able to work on my driveway. It turns out I only need to remove the rubber tube connecting the PCV device. I left the PCV in its place but turned the device's port towards the front so it is out of way. Once the rubber tube is removed, the #1 ignition coil is in the view. As stated in Lexmus' procedure for replacing spark plugs, a 10mm wrench is needed for this. Use the 10mm wrench to loosen the bolt and use fingers to do the last couple of turns and pull out the bolt. Removing the coil is easy - lift out the coil as much as I can and then pull the coil towards the clear space a little for complete removal. The coil's tip is all silicon/rubber so the little bending did not leave any damage.

The most difficult part in my replacement of the #1 ignition coil was to disconnect the electric wiring port. This must be done while the coil is in its tube. The connector did not want to disengage at first. With fingers pressing the release tab and very little pulling space, I had no other way but be patient and trying multiple times. It took me about 10 times to finally make the disconnection - in between I had to walk away several times to rest my back. I am 6 foot 2 with big hands. So bending on vehicle and hand work in small spaces always leave noticeable impressions.

Fortunately, thanks to the advice and inputs on this Forum, this is one of the only few times that I did not break any thing while working on a vehicle! It took me about an hour, including walk-aways, tea and coffee.

Started the engine on driveway and it runs smooth as usual. The only thing left is the CEL which is still On. I guess once it is on the road driving a few miles it would be off? I don't know a way to reset this CEL by clearing the P0301 code. My previous experience with replacing A/F sensors is that the light will disappear after a few miles of driving.

Thank you all very much. Here are some photos for teasing.

After removing the PCV rubber tube:


Both the #1 coil and the bolt are in view:


The new replacement coil - Denso 673-1301:


The bad coil, a Toyota 90910-02234:


The only "casualty" is a few minor scratch on my left hand, mostly from working the wiring connector: