My wife's 2010 RX350 with 75K miles on it , the check Engine Light came up with code P0303 (cylinder misfire). Since the warranty is out already so I went to my mechanic and had the spark plugs and the back ignition coils replaced. After a week, the light came back on. So I went to the dealership and they said the engine needs to be taken apart because of low compression and valves could have carbon build up already. They are saying that it would cost $3,500 for that. Not sure if anyone had the same issue. Recommendations will be appreciated.

 

I'm certainly not a tech but I would think since its only cylinder #3 that is misfiring its more likely a bad plug, coil or injector. Did your original mechanic diagnose low compression in that cylinder?

 

Plugs were replaced and the back coils and injectors were checked too. Dealership was the one who diagnosed a low compression on cylinder 3.

 

i would shot gun the 1 injector before doing any engine work.

 

Find a shop, possibly the dealer, who can run a cleaner through the engine.
No, not the retail variety we can buy at the parts store. There are some very potent chemicals out there.
Check the compression after the cleaning. MIGHT improve it some.
Not a big fan of the "snake oil fixes" but it will be relatively cheap alternative compared to pulling the heads.

This method saved our bacon just after we were married. Let's just say this was back in the early '80's.
Jane was driving a 1 year old Accord/ 5 speed up & down a city street to work & back, home & back for lunch everyday too. Problem was she was travelling all the way at about 25 MPH in 5th gear, all the time.
Quit on us one night & had it towed to the dealer. Valves would not close fully in 2 of 4 cylinders.
Easy fix only because it worked. We were looking at pulling the head on it as a last resort.

 

What do you mean by shot gun?

 

The dealer put some cleaner for now and will see if the check engine light will come up again.

 

Took it to Toyota and said the same thing that engine needs to be taken apart to clean carbon build up in the cylinder because of low compression. Cost would be around $3K++. Decided to trade it in for '14 RX350 and got $19k for it. Thanks guys.

 

Thanks for the follow-up, and congrats on that new-to-you RX!

 

congrats on the 2014! you will like it very much. but i still do not understand the carbon build up? thats odd.

 

Francis, just for my own understanding of the cars service life, what type of driving did you do re: highway VS city and what type of gas did you burn? Each of those could possibly have been a factor re: carbon buildup.

Also did you use a dealer for oil changes?

Thanks

 

Hi,

It's a mix of highway and city driving. Only premium gas was used specifically Chevron, but according to the dealership there was a bad batch of gas here in Houston that was distributed. Did not use dealer for oil changes.