We have a 2005 rx that is driving us insane, and broke. At approx. 40K miles the car would begin shutting itself off after 30-45 minutes of run time....after 2-3 minutes of cranking it would start and run normally. Initially, this occurred every 1-2k miles, but became more frequent. Dealer couldn'tfind the problem, but suspected the fuel pump, which I replaced with no change. New plugs, crankshaft positioning sensor followed, also to no effect. Now we're at 80k and every time the car is driven it will shut itself off, sometimes taking an hour to restart.

The dealer now wants to replace the catalytic convertor.

The engine shuts off after driving and then slowing down, such as at a stop light.

Suggestions? Many thanks in advance.

 

Has the dealer checked the cat and confirmed it has failed, or at least confirmed that it looks like it has issues visually? Were their any codes pulled from a CEL (flashing or steady) warning light on your guage cluster that indicated a problem with the cat?

There is some possible connection between the cat being bad and your problem, but it could show up in other possible ways including loss of horsepower in the upper end of the RPM range, especially with the engine under load. Replacing a cat under "hunt & pray" diagnostic process is a pricey guess to be making.

Also, did you ever get a valid compression test done on the motor?

 

they did not do a compression test....they didn't remove the cat, just said they got a "bad cat " code. I crawled under it, the cat is beaten to hell, part of the skid protection for it is worn through.

Another thing that worries me is that its gradually losing coolant, but not from under the car, I'd read that it could be lost into the "cylinders", then blown into the cat, killing it.

I've replaced the plugs every 30k, but the coils are original. Also, the car is at 84k miles, so it'll probably be getting a midpipe, as the $1490 for the oem cat is a bit rich for me.

The car is sluggish from 4500rpm and up, its nearly impossible to pass at interstate speeds.

 

I think the car has a emission warranty check that out see if its still apply.

hows the color of your coolant? if its burning coolant, the spark plugs might look different and your exhaust gas might look different.

check slow leak on the radiator.

 

Disappearing coolant not attributable to leakage or burnt looking coolant + bad top end performance + your other symptoms sure would get me thinking about a compression test.

 

And possibly a new catalyzer as well

 

its getting new coils and a midpipe Monday.....I mentioned the disappearing coolant to the dealership, but they never reported back with anything.

 

why are you wasting money?

 

As in repairing the car? That should be somewhat self explanatory, no?

 

You're not repairing the car, you're throwing random parts at it hoping to fix the problem.
Inspect the catalytic converter, check the compression and make a decision on what to buy only after you have thos results!

 

Ah, gotcha. My point on that is I can have a midpipe and coils on the car for less than the dealership wants for a diagnostic test.

 

A compression test shouldn't cost more than 100$. A midpipe alone costs more than that and probably won't fix the problem. Same for the coils, they may help but if you have low compression they're not gonna fix the problem.
You should definitely check your compression first and then proceed to move on to the next item.

 

bse50...I agree with you whole-heartedly, but they will most likely make him buy coils(did I read it right.....you might have 80k miles on these coils?) before doing a compression test anyway. Will probably want to do engine cleaner as well if first check comes out marginal or low.
I don't like the fact that he's going to throw a mid-pipe on it and assume that will be a cure all.
OP.........FYI.......the CAT has an 8 year 80k mile warranty in the USA, so even if you plan to put a midpipe on it(CAT delete), then why not let them check the CAT and give you a new one?
My issue here is that it seems like a classic case of ignition issues............old coils.........leading to un-burnt fuel dumped into the CAT, and has most likely broken it up to the point of clogging or at least restricting....which leads to other issues if not taken care of in a timely fashion.

 

Well, as far as I'm concerned a dealership could try to make me buy whatever they want but if I ask for something specific then they will have to do it and stfu. In the end i'm paying for it!
Well, I have actually only been to the dealership only a couple of times for minor warranty works since my car never had a powertrain warranty (bought "used" with 6000miles and the 1st owner skipped the 2nd year\40.000km service).

 

Yeah, its over $100 for the test, I'm having a local fab shop build a midpipe, I'm not really concerned with it being polished/titanium, etc.

Yes, 86k, no warranty on cat, and yes, the original coils. The exhaust smells HEAVILY of fuel.

It will get a compression test soon. Since they failed to check into the coolant problem when I took it in I might coerce them into throwing that in.

 

Change those coils immediately!!!!! Good thing you have those coming Monday.
Guess we will see if you have low compression or not if you aren't going to get it checked.