00 Rx300 Ignition Coils, Replace All Or Just The Bad One?

[sigtauenus]

We are at roughly 160,000 miles on the 2000 RX300. We replaced 2 of the ignition coils with Lexus dealer parts about 18 months ago, and today I think another one failed based on the symptoms. I'm about to take it to get the codes read to verify. Engine runs and car is drivable, but it runs really rough at idle with transmission in drive, and runs rough on acceleration. If you step on the gas lightly it is ok but obviously that means it takes awhile to get up to speed. This is exactly what happened last time.

Assuming the bad cylinder is not one that we replaced already, should I just go ahead and replace the other 4 now? I deploy with the military and need a reliable vehicle for my wife while I am gone. If this is a case of one going indicating the rest will soon follow, I'd rather spend the extra money on parts now while I can do this myself than pay 2-3 times as much a year from now when my wife takes it to a shop.

[Filehorse]

I had exactly the same situation occur on my 2000 RX300 AWD. I had the first coil fail in 2008 and the 2nd coil failed in the summer of 2009. I could see the pattern and opted to make the preemptive move and replaced all the remaining ignition coils. If you plan to continue driving your RX, I would go ahead and replace the remaining coils as well. Otherwise, Murphy's Law suggests the next one will fail at the worst possible time - i.e. miles from anywhere on a dark, rainy Saturday night. On mine, after driving about 20 or so miles with a failed coil, the transmission decides that it will not go into overdrive and at that point, you need to be close to home or someplace where you can get it fixed.

Lotsa luck.

[sigtauenus]

We are at the same point now, transmission will not go into overdrive. I'm glad you mentioned that as I thought maybe the issue was compounding but gut feeling was it was related to the coil.

Codes came back P0300 for random/multiple misfires, and P0301 and P0302 for cyl 1 and cyl 2 misfire respectively. At least its on the front bank. I'm pretty sure we changed 1 and 6 last time, and based on other topics I read, there is a tendency for other cylinders to misfire when one coil fails. I suspect the problem is really only with cyl 2 so will check that first to confirm.

I need to change the valve cover gasket on the rear bank but haven't because I didn't want to pull the intake. Now I might as well and do both at the same time, ie, gasket and coil packs. Fortunately the rear bank isn't a problem yet, but I'll put that on the list of things to do...

[sigtauenus]

Nevermind. Just realized #1 is on the back if I'm reading this right. I guess I'm pulling the intake tonight after all.

[sigtauenus]

Well, I know I replaced 1 on the back and 1 on the front, but don't recall exactly which. I know the one on the back was the one closest to the passenger side so pretty sure that's #1. I just ordered 3 coils from mylexparts as well as spark plugs (might as well, right?), so I'm going to change all 3 on the rear bank and then rotate all 3 through the front bank to identify the problem coil(s) and then keep the 1 or 2 good ones as a spare.

[nobu]

We are at roughly 160,000 miles on the 2000 RX300. We replaced 2 of the ignition coils with Lexus dealer parts about 18 months ago, and today I think another one failed based on the symptoms. I'm about to take it to get the codes read to verify. Engine runs and car is drivable, but it runs really rough at idle with transmission in drive, and runs rough on acceleration. If you step on the gas lightly it is ok but obviously that means it takes awhile to get up to speed. This is exactly what happened last time.

Assuming the bad cylinder is not one that we replaced already, should I just go ahead and replace the other 4 now? I deploy with the military and need a reliable vehicle for my wife while I am gone. If this is a case of one going indicating the rest will soon follow, I'd rather spend the extra money on parts now while I can do this myself than pay 2-3 times as much a year from now when my wife takes it to a shop.

[nobu]

I suppose at some time or another, the coil(s) are certainly going to need replacing. However, I've gone through the whole procedure of plugging in the code reader, seeing what cylinder is misfiring, interpreting the code to be a coil, and replacing it.

But now after about 10 thousand miles, the check engine light goes on again and it's the same code. The coil again. i know if I replace it, it will run just fine but I feel it indicates an additional problem elswhere. Anyone out there ever had that problem or know the reason for this?

[lenore]

I would be very careful to observe whether there is corrosion on the plug top or the coil pack is corroded where it plugs onto the top of the plug...I put dielectric grease on mine to keep moisture out and stop moisture....Moisture can cause premature failures....do to arcing. Also always used iridium NGK or Denso plugs (OEM) never, and I say never put in Bosch...

[mathewd23]

Hi guys, I just replaced all my 6 spark plugs on 2000 Leuxs Rx300 which has 98K miles with NGK Iradium, and i had a P0302 code on the scanner. I reseted it, and never saw the CEL come again, but when i am driving especially on highway at 65 miles/hr It has a rough driving, why is that, Does that mean that due to a bad ignition coil, i could have that problem. Also if the car is in park or neutral. I dont feel the misfire, but if i stop at a light. I can feel the misfire. Any help will be appreciated.