beatdownbox

I purchased a used 04 Rx8 about 3 months ago and have had problems since I've gotten it home. It has 114,000 miles on it. More recently when I start it, it is extremely loud. When I slow down the car begins to shake and sometimes completely cuts off right there in the middle of traffic. The rpms flicker and it just cuts off. It has been in and out of the shop but the the problem still persists. Also when I drive it sometimes it does not speed up like it should and I have to kind of slam the gas to get it to go even a little. The last time it cut off on me it was towed to Mazda where I was told it needed a catalytic converter. That work was done yet the car still drove the same. I always wait for it to warm up before l drive it until yesterday when I had to move it out of the carport and parked it into the yard. Now today it won't start (again). Does anybody have any idea at all? I am running out of options and patience and have spent over a thousand dollars on this car in repairs and have only had it for barely 3 months.

Please help!

RIWWP

iTrader: (2)

Did you get a compression test when you bought it? (You could have bought a bad engine that was already failing)

When was the last time the coils, plugs, and wires were changed? (at least 1 of the 12 pieces will typically fail by 30,000 miles)

The heavy shaking is probably also destroying your motor mounts if they weren't already busted

Then there is the MAF sensor, e-shaft sensor, and front O2 sensor that could be failing and/or fouled and in bad need of a cleaning.

... and the fuel filter could be clogging, the fuel pump could be dying, or you could have a grounding problem.



Yes, it's a big list of possible items. Things cascade in failure pretty quick, and just about any of these will take out a catalytic converter pretty quick if not addressed (even if you didn't know something was failing, it doesn't stop the failure from destroying the cat while you keep driving).



If you can get more detailed about any history of the car before you bought it (you did your research right?) then we might be able to start narrowing it down. Otherwise, start by cleaning the MAF and the ESS, if the does nothing order new coils, plugs, and wires (please god not from the dealer, but from vendors here for far cheaper parts that are still OEM and will support you after purchase). If still having problems move to the fuel filter sock and the front O2 sensor. If you don't already have compression test scores for the engine, then go get a compression test from the dealer anyway. Chasing parts with low compression is an exercise in futility, and a 2004 with 114,000 miles probably has low compression.

Old Rotor

Have you read where bad ignition coils can cause the cat to expire? Have you read this sticky? Read



https://www.rx8club.com/rx-8-discuss...t-here-202454/

beatdownbox

It's very possible I bought a bad engine, I did not run any tests as we bought from a mechanic who seemed very loyal -_-

Not sure about plugs & wires but new high performance spark plugs were just bought and changed out.)

UPDATE: So I just got my car out of the shop (has been almost a week) spent 800. I "test drove" it around the parking lot & already notice the really bad shaking (STILL) now this was only when driving a slow speed or braking and being stopped. I informed the guy who had apparently fixed it and let him know that it is still shaking and the rpms still go down in which he responded with "yeah that only happens with the AC on, the RPMS will go down but it won't cut off." I was definitely not happy about this but I took his word and attempted to drive it home. Okay, AC is off and I'm driving it and RPMS are still going down, at a red light starts shaking bad, and get's worse. The car cuts off. I wanted to cry. I tried cranking it back up almost didn't start but as soon as it did, drove it straight back to the shop where he apologized and said he was gonna try and put premium gas in it and test it out tomorrow.

So after going to about 4 different automotive shops I'm left with the same problem, the shaking that gets worse when AC is on cutting off when slowing down or stopped.

beatdownbox

BTW, does it really matter what gas you use? I have been using regular unleaded and have been told it doesn't matter, but the previous "mechanic" said I needed to use premium.

RIWWP

iTrader: (2)

Um, yes. It does matter. Should have a "premium only" sticker inside the gas door.

87 octane can and will damage a good compression Renesis... Older engines with failing compression can often get away with 89 octane, but only 87 once the engine is pretty much dead anyway.

beatdownbox

there is no sticker, & like I said I've been told by multiple people including 2 mechanics that you can use regular unleaded.

RIWWP

iTrader: (2)

Well, choose who you want to believe...

https://www.rx8club.com/tech-garage-...1/#post4365460

Take a look at the fuel system information.


Dropping the octane in a piston engine means that the ECU detects knock and pulls timing. By the time the ECU detects knock in a rotory, it's already dangerous, and pulling the timing doesn't do nearly as much as it does for a piston engine.

Detonation from too low of an octane can and will damage your apex seals in short order.



I suppose you can probably find someone that tells you that running diesel is fine too.

Choose who you want to believe.

beatdownbox

I'm not doubting you nor am I saying I don't believe you. I will take your advice and use Premium but for now, I would just like some help with my main problems lol, thanks.

kevinande

Quit throwing good money after bad, take it to the dealer and get a compression test. What is it with people and fuel. Over a full tank of gas you are talking maybe $5 and that's assuming your completely empty and a .30 spread.

beatdownbox

A compression test was done at Mazda where I was told the catalytic converter needed to be replaced. That was done. Still has these issues. but thanks.

04Green

iTrader: (1)

Follow the list in the $100 thread below (in my sig), specifically the following items: MAF Clean, Ground kit (try the star washer on existing connections approach), and clean the ESS. Would not hurt to look at the plugs as well, but see if getting the right data to the computer makes things run a little better. All told, the list above will run you $20 and a few hours of work. That includes the after work beer.

The rest of the stuff applies to a 2004 as well, and is recommended. It really helped me.

xexok

Did they tell you the results of the test? You should have gotten a piece of paper with 6 psi or kpa numbers and 1 or 2 numbers for rpm.