I have a 2010 RX 350 with 127,000 miles I had the car for about 2 months not runs great, I noticed when we have heavy rain the car is a bit difficult to start, it will start on the first try but it is a slow crank. not sure how old the battery is or when the plugs or coils were changed.

 

An autozone type car store can check the battery and charging system at no charge. The plugs should have been changed at 100K. You can pull one and check the gap - a plug with 127K will have a gap out of specs. The coils should be fine, this car will throw a code if a faulty coil is detected.

 

Yes, I went to advance auto they checked the battery and charging both were good, I will check one of the plugs, my guess they are original. Car idles very smooth feel like it is not even running. Thank you for your advice much appreciated.

 

Open the hood, and check for any leaves or debris on the plenum, in front of the windshield wipers. I had a crank, but no start condition after a heavy rain, and had a lot of leaves in there. It was 5 years ago, and the car would not fire (cranked good), until about 5th try. I think having ignition on for a while, dried out a wet connection on the ECU or other connection enough to sort it out. I could never reproduce problem, despite hosing it down, and decided the leaves in plenum directed the water over a connector somewhere. GL.

The other thing is to check the state of the "immobilizer" light/status. Search for what that should be, but the RX350 will crank but not fire if the immobilizer is unhappy.

 

Wow very interesting yes In did notice some leaves on the plenum I will remove those leaves in the morning, I had a computer scan today and everything else seems good. Car starts amazing on dry days even light rain but have just a hard start slow crank. Thank you for the advice I hope the leaves are it.