Okay so my 05 shinka is on it's last leg on the engine. I need to take it in to the dealer to get the engine swapped out but I'm procrastinating a little bit. I'm 99% certain compression is shot on at least 1 rotor. I get about 7mpg, feels like i'm driving a camry, won't start above 180*, idle feels choppy, and more. But the issue I'm having is i'm trying to get everything buttoned up before i take it in so they can't tell me I somehow caused the engine to die.

I have a weird noise that started up recently. I had the radiator changed about a week and a half ago as the reservoir broke right where the cap turns on and my assistant when I was replacing it snapped the nipple off the top of the radiator. The car did run hot, about 235-237, but the gauge barely moved and I don't believe it overheated. It started right up and has driven fine for the past week and a half and 250 miles.

Just yesterday I went to go from a stop and noticed as I was letting the clutch out; what sounded like a metallic grinding. It seemed to go away once the clutch was all the way out and going but it seemed to come back in second. I couldn't hear it after because of engine noise and wind noise. When I came to a stop I checked everything that could be rubbing, no hoses, no lines, no wires, no shrouds, no screws, no pulleys, no belts, nothing showed signs of rubbing. Checked all wheel wells and everything.

While under the hood I noticed a weird rattle coming from the intake manifold area. Imagine a plate of dry rice sitting on a subwoofer, a rattle/tinkling noise was very audible. I know the intake valves can stick open and closed from carbon buildup but I was always told that if you vary the throttle position it will rarely stick. Plus at idle I wouldn't think that the rattle would be that pronounced and even then, if that is the case, I wouldn't think the car would be drive-able with that much rattle going on.

It doesn't sound NEARLY as pronounced as MIAC and it isn't audible inside the car. I almost thought it was low oil as the grinding seemed to match the cars rpm up until it stops, so i thought maybe it wasn't lubricating properly. but oil is topped off 100% less that 500 miles ago and I check it every 100 miles when i refill the tank. I don't premix and I use 5w20. Is this rattle just a symptom of a dying engine? Should i be worried about something else?

Also as a bonus question, I have no catalytic converter, the previous owner gutted it. This poses an issue getting the engine warrantied as the CEL is on for that o2 sensor. I plan on getting an exhaust system put on it so I'd rather not drop money onto a cat that will only be on there for 6mo-yr and potentially even cause more problems on the new engine. Is there a way I can just rig a resistor into the o2 sensor wiring so that the ecu thinks it's getting the right response and the CEL goes away? I'm going wideband and cobb accessport with the new engine so it wouldn't be anything permanent, just a temporary deal to get the CEL gone.

 

What warranty do you have? The original is long up. Whether you have a cat or not should not impact warranty coverage on the engine, they would have to prove that the lack of cat caused engine failure, which isn't possible.

Not that I think your engine is in good shape, but when was the last time you changed the ignition coils? It'll be difficult for the engine to run without spark.

Also 235-237F is overheat territory. The gauge is designed to move way too late (which seems common on cars these days).

 

The Warranty is one that was offered from my finnance company that I made specifically sure would cover the engine components if compression became an issue. I already talked with them before getting it to make sure everything would be covered.

And it's not whether or not i have a cat that would cause the issue, its the CEL itself. The dealer is being a pain and saying that the CEL has to be taken care of and the warranty doesn't cover someone intentionally gutting the cat. So I would be out of pocket that.

Ignition coils and plugs were changed at 55k miles and its at 70k now. They are oem so I'm sure they aren't top notch condition but the should still be good for another 10k miles. And ya I know the gauge is stupid on the cars for temperature but everything I was looking up was above 240 is when you have to start getting worried and anything above 245 you might as well call the engine toast. The car runs at 210-215 on average in the 95* weather we been getting down here.

 

Hmm. The dealer can't force you to perform a repair, check your local laws. They are not the safety and emissions police.

Long story short, the best way to fix the cat CEL is a MazdaEdit or Cobb AP. You can try getting a cheap cat, but that's money fown the drain. Resistors won't do it.

Do you have another dealer you can work with? If they're being a pain in the *** about a CEL, imagine the engine replacement. Or, let them know that they're about to get or lose a signficant repair job based on what they can do for you. Their call.

 

Ya they are the only dealer near me by a good margin. I've taken it to a couple of independant shops but none of them want to touch a rotary and the closest rotary specialist is in missouri, a 10 hour drive.

I gotta take it in for the airbag recall so I'll double check with them but last i remember being told was that they had to clear all the CEL codes they could before they would 100% confirm bad engine amd replace it.