Banshee8

2005 RX8 6SPD 87,000 miles

Engine requires 1qt of oil or more each fill-up every two weeks. Catalytic converter is causing substantial back-pressure and deteriorating. Coolant level is constant. Engine pull is strong. Hot hard start, most likely linked to failing cat.

I'm located in SW Virginia, not near rotary-skilled dealer mechanics to my knowledge. I have no oil service receipts, which will cause me to argue my case into warranty work. Second owner of car, also.

What are your opinions on these options?

A) It's worth it to risk extra-warranty expenses and low skill at local dealerships. Pursue core warranty work and pay $500 for misc shop expenses. The bonus is that I get a new cat for free. The risks are that the engine is not warranted under the diagnosed problem, and that I end up paying for diagnostic work, with no fix. Also, there is a reasonable chance the work will be faulty.

B) It's smarter to hire a skilled, dedicated mechanic in the long run. Don't bother trying to get the job done right at a dealership. Pay around $2k for an engine rebuild, and another $450 for a BHR midpipe. Take recommendations on the best skill I can drive to and get the job done right. Pay up, void the warranty and call it a day. The risk is that the warranty work could have been done by a skilled, knowledgeable dealership I'm unaware of.

C) 1 or 1 1/2 Qts per fill-up is a lot but not unheard of under normal wear and tear. The problem is trying to make a Cat work under that consumption. Knock out or replace the Cat with a $450 BHR, perform a general engine decarb and see how far I can go on that. If the problem is the shaft oil seal and not an edge gasket the problem might not get any worse. This is a gamble, but really cheap particularly if I just knock out the cat and insert stainless baffles. Void the warranty and save a lot of money now. Don't bother hoping that the dealership can do the job right. Spend the money only when I absolutely have to.

D) You have a better option.

Thanks in advance for your experienced opinions.

200.mph

iTrader: (9)

your 05 is still in warranty? when was it first sold? bad cat can lead to engine failure, when was the last time you replaced ignition? are you having hot start issues? that does seem a bit high for oil use.

blckninja

iTrader: (1)

With the oil burning issue how many miles are you driving? Possible issues:

◦oil control ring failure
◦vacuum leak
◦e-shaft seal leak
◦oil pan leak

Issues for hot start:

◦battery failure
◦starter failure
◦ignition failure
◦fuel system leak
◦e-shaft sensor fouled

He said he was having hot start issues, and yea when was the last time ignition replaced is a question. What have you done to try and fix the hot start and oil consumption?

A) The only way the engine would be under warranty is if your car was sold in 2006 since those warranties are expireing this year. So if you car was sold May 27th, 2006 OR sooner your SOL with engine warranty.

B) That would be smarter, most places give a short warranty on their work, but make sure to get it in writing. Also again, we don't even know IF your engine is still under warranty since we don't know when it was first sold.

C) Getting the midpipe will definitely help you in the long run. Will never have to replace that piece again unless it gets broken for some reason. Also, they have awesome customer service so thats always a plus. And replacing the cat wouldn't void the engine warranty, the dealership would have to prove that doing so created the loss of engine compression.

Which also leads me to the next thing, how do you know you need to get the engine replaced? Unless it fails the compression test, drive test, or vacuum test then they wouldn't replace it under the warranty IF its available. Just because the cat failed doesn't mean that the engine would fail a compression test, which the dealership would do before they even considered a replacement.

Banshee8

Good stuff,

1Qt = 160 commuter miles. but,.. many, many more trip miles. Commuting is burning a lot more oil than taking a long, hot trip.

I thought backpressure from a bad, hot cat could impede hot starts?

I replaced the ignition with new stock about two years ago.

A) Crap, yeah you're right. Well.. easier decision then.

B) It's 2005 model, but no clue as to the sale date. I better check.

C) The engine is using an unusual amount of oil compared to its own history. I know oil use varies, but 1QT or a bit more per fill is notably high for my car. And, the increase in oil consumption is directly correlated to the cat failure, which is also only 2 years old.

Banshee8

No, I'm wrong it's not under warranty. I can't do math and optimism at the same time.

The ignition is a couple years old. Replaced it myself with new. The hot start issues might possibly be tied to the backpressure from the cat... I suppose.

Yeah, the oil use I know varies a lot for diff people. But this is an unusual rate of consumption for my car. I HAVE to refill oil when I refuel at 3/16 tank.

200.mph

iTrader: (9)

time isnt as important as mileage on the ignition. how many miles on it? i would knock out the cat. what starter and battery is in your car? it wont help the oil use but could be tied to starting problems. the oil pan is known to leak, does yours?

blckninja

iTrader: (1)

Ah yes I didn't think about that, the cat could also be another issue for hot starting. Your best bet might to replace that first since you need to anyway.

Banshee8

Agreed. Sounds like I have a hot date with the cat, a rod and a hammer. That'll get me going again and give me more opportunity to observe the symptoms. It'll also take the backpressure off the engine while I wait to buy the midpipe.

Banshee8

Figure about 20,000 miles on these ignition coils. Worst case scenario.

Yup, gonna knock out the cat. See where that gets me. The oil pan doesn't leak, and the driveway is nice and clean. The apron under the car is clear of fresh oil.

The only thing I'm keeping my eye on under there is the OMP, which is coated in some oil, but isn't dripping.

200.mph

iTrader: (9)

ignition is usually only good for ~30k but can crap out/become weak much sooner. knock the cat out and replace your ignition

hoosier1104

iTrader: (2)

BHR is a good way to good. Just saying.

Banshee8

Yeah, I'll have to pencil in an upgrade for later this summer. New plugs and ignition following the decarb. I'll have to look at some of the third party upgrade options. Maybe BHR again.

On the topic of the midpipe. If I get rid of the cat, there's no reason to have an air pump correct? I'll need to perform an air pump delete.

Williard

iTrader: (18)

Banshee you are correct, if you get rid of the CAT you will no longer need the airpump.

Banshee8

Just a follow-up on the cat.. I removed the catalyst last night and reinstalled the stock pipe. Huge performance difference after being clogged! I pushed it very hard over some mountains, with revmatched downshifts, redline upshifts, etc. NO CEL light ever stuck. I did have one cel blinking following the top end of third, but that is normal for this car. I might indeed have ignition issues, particularly b/c coming down from a 5k rev after a few minutes of warmup results in a ton of white smoke. The issue seems to disappear with a fully hot engine. The smell is rich at startup, like a lawnmower actually. A hot engine smells almost normal as with a functional cat. Not bad. Engine pulls very well now. 7k and upward is much much improved. I'm looking up alternative coils, new plugs, and a high flow air filter to complete the overall tune-up.

Williard

iTrader: (18)

A flashing CEL is a misfire. No doubt about it. Whether it blinked then went off or blinked and stayed blinking running the car like that is not safe for your ignition system nor your engine. That would be the first thing i look into. Have you upgraded your ignition system at all?? Why not splurge a bit and pop for the BHR ignition system. It is by far superior to the stock system.

Banshee8

I agree. But, I've read a lot of snippets about the BHR kit being just an adapted set of truck coils or corvette coils with matching wires. I'd like the convenience of the prefitted kit. But for $100 or more in savings i might see if i can put a kit together myself from various suppliers. I'd like to put a little money elsewhere also, particularly at the air intake.

Banshee8

Yeah, n/m I'm just gonna go BHR. It's a complete, warranted solution and the price difference to other products isn't significant enough to merit the trouble of a home grown solution. I just want it fixed.. right?

Williard

iTrader: (18)

The BHR kit is amazing to say the least. Any issue's Charles has he handles quickly and correctly. You wont regret the purchase of them. That i can promise you.

TeamRX8

iTrader: (25)

or you could buy a $15 tool, check all your coils and wires to figure out what's wrong, and just replace the defective part(s) only, assuming there are any.

now every time I post this the accusations of bashing will abound, but it's just common sense really ... even if you determine everything is fried and you get the kit any way, it's entirely possible you'll still need the tool. It's exactly how this procedure came about and applies to all "smart" coils & wires including the OE parts

https://www.rx8club.com/series-i-do-...-wires-222641/

Williard

iTrader: (18)

I agree 100% team that everything should be tested. Literally just to figure out what component is bad. I will say that SOMETHING within the ignition IS bad due to the flashing CEL. Again, A flashing check engine light is a misfire, whether it sticks or not it's ALWAYS a misfire. Now there are a few ignition solutions i could provide but, the one that is used more often than not is the BHR kit. I have one, i know of MANY other members who have them and love it. Charles has excellent customer service. Now im not saying that these coils will never go bad because they are parts and parts will ALWAYS go bad given enough time. This kit is just a solid upgrade from stock and IMO you will have less issue's with the ignition system than with stock.
Again as i said earlier i believe it should all be tested anyway. The tool you suggested is a tool that i have and i think any mechanic would love to have it in his tool box.

Banshee8

I've ordered the BHR. Got the plugs also and the K&N filter. I'm gonna clean the current plugs in the meantime just to keep things within reasonably safe parameters. The ignition really isn't happy right now. is that necessary or will the BHR be here pretty quick?

Banshee8

Hey guys thanks for your input. I hate dead-end strings to here's the end of the story: K&N filter is installed, BHR ignition installed and the cat is knocked out. The engine has been running better and better over the last few days as the fuel trims adjust and as I rev-limit for carbon blow-out.

Right after the BHR kit was installed the engine still produced a considerable amount of smoke, even after a warm-up, and the backfires were quite impressive. However power was notably, notably improved. Now, days after, the backfires are much harder to elicit from the engine and the smoke is much less, although it's not completely gone. It's like the engine is "getting better" over time. I wail on it, so the BHR ignition is getting its chances to shine. After 6000 rpm the acceleration becomes scary. At the top of each commute I coast into the backstreet I park on and bounce the rev limiter. With the cat gone it sounds amazing! Like a rally car or something. The car is otherwise bone-stock (just a SS clutch line and modified engine mounts) with the factory GT package and skirts, so it's fun to have a car that other RX8ers aren't necessarily expecting to sound like a track car. To be fair, it finally sounds like what it's always looked like.

I do have to warm the car for about 5 minutes if I want zero rich-running white smoke. I guess that's the price for going catless. I'm not a fan of the cold engine smell, but keeping the windows rolled up and the A/C cycling negates that. The hot engine smell isn't bad... kinda smells like you're running a real road machine and not a minivan. However, I know my wife wouldn't like it. One day I might have to go hi-flow cat. Maybe.

Overall I'm crazy about the recent fix. The theoretical numbers point to around 262 horsepower up from 247. But... I gotta say the difference for me was much more than that. I must have been running not much over 220 (or worse) with my ignition and cat issues. It's a whole new car now. It'd seem brand-new if my engine mounts weren't stuffed with urethane... and if it didn't stink.

The last issue I'm looking at is oil consumption. It's possible that it's burning, but the evidence for that is scant. Any smoke is cold engine smoke, and the smoke is always white-white. Coolant is steady. Compression is spotty on a hot start, but that could be my sucky old ignition causing carbon buildup. 44k might fix that. The oil isn't leaking overnight, so I need to clean the engine off (overdue anyway) and see where it pops up again... most likely dripping during operation.

Anyway that's my update. Thanks for your help!