Hey guys recently my car has started making a clunking noise when I start it. It is an 04 AT with about 40k miles. I recently changed the spark plugs and replaced the battery with an Optima Red Top 34r. Does anyone know what could be causing this? I beleive the ignition coils might be bad since they are the original ones. Also, the car seems very laggy until about 3k rpm then it accelerates fine. The car just started backfiring yesterday, more than normal. I have a Borla exhaust which I got last year. I am most likely getting my tranny replaced on Wednesday since there is a loud rattle when the car changes gears and vibrates excessively in the back at idle. The car was also a little shakey in the back off the line. If anyone has any ideas, let me know. Thanks.

 

No way your coils are causing a clunk....If the tranny is acting up it is the most likely place to start.....

 

You must be a little bit more specific. Is the issue during you cranking the engine at start up? Or is the clunking during driving off the line from a stop?
Does the car make the clunking ( and I use the word lightly, not knowing the exact sound) when you turn? It is possible the a universal joint has gone bad. Either on the drive shaft or on a rear axle. Neither of those problem I can recall being mentioned on the forum.
It's just hard to determine an issue over the Internet. Supplying the most relative information is so helpful in these issue determinations.

 

The clunking occurs during cranking. It doesn't occur every single time, but almost all of the starts. The engine temp doesn't affect the clunking occurring or not. Also the car feels very laggy off the line until about 3k rpm. After that the power is fine. Could this be a bad cat since the car is also backfiring, which it rarely ever did before?

 

my car is sorta doin the same thing but only when i shut it off. i pin points the the sound was coming from tube under my exhaust manifold i havnt lookd into what the tube is yet but i kno for a fact thats where is is coming from but all the same things r goin on like urs besides the starting and shuting off

 

UPDATE: So I got the car back on Wednesday and it ran a lot better than before. They de-carbed the engine, as well as replaced the throttle body. Now the car has the same issues as before, since the tranny wasn't replaced. It still rattles when changing gears. It still makes the clunking sound during startup. It starts up fine, but just makes this sound. The car still feels laggy and has lost low end power. It seems like something in the rear is causing the car to sputter. I think it is the cat since the car is backfiring more than normal. Anyone know how to get the dealer to fix this? I had them check it before, and they couldn't find the problem. They had the tech bang on the converter with a rubber mallet. The car seems like it is choking when acelerating from a dead stop.

 

Bump. Does anyone have any ideas how to fix this? I am thinking it could either be the fuel pump, cat, or the alternator. Any info would be great. Thanks.

 

dam bro sounds like you have the same exact problem as me my car also rattles in the back when its on and its really laggy and kind of pulls back until like 3.5 4rpm and wen i crank it ... it takes a minute like sumthin is wrong with the fuel pump pressure or sumthin but idk whats wrong with it yet im taking my car to mazda like next week because its really annoying ... some days it will stall on every stop but then it goes away in like 2 hrs until the next time it feels like acting up. i dont know much about rotary but i also think it could be a coil ma boi thats a mechanic told me it could be a coil i think it has something to do with the fuel. idk post if u get it fixed.

 

I'm subscribing because I'd like to know the cause of your guys' problem. Blazin 420, do you have an AT or MT?

 

When did you last change the transmission fluid?

Or checked it's level?

whirring and thunking sounds like low fluid to me.

 

One of my friends has a problem similar to this on his '04 RX8.

He doesn't have the noise though, just the loss of power below 4000 RPM and the hard starts.

He's getting a compression test done in a week and if his numbers come back OK I'll hopefully have the BHR coils at that time. Since his car pulls harder than mine at higher RPM's I doubt its the catalytic converter.

 

i got an mt an idk if i said this already but the car like shakes and it takes a while to atrt up like about 4 seconds it sounds like its coking i just made an appointment to take it to mazda today and i did not change the transmission fluid because i just got it like 2 weeks ago and never had time to get to that but the guy that sold me the car said that there was a problem with the fuel injector from the dealership but i think it has something to do with my clutch ... forgot to mention that when i start it up in the morning theres like a weird sound that goes away when i step on the clutch and another problem is when i first start the car and backup in an angle or take off in an angle and this only happens when i first start the car and move like 3 ft in an angle something makes a rubber band sound like a spring or something....idk does anyone know how to solve this stuff i can fix it but im not a diagnostic person i just know how to work with it

 

im at the mazda waiting room for service getting ma car looked at ill tell you wht was wrong

 

Sorry I haven't responded, been really busy. Anyways, I got my car back two weeks ago after it being at the dealer getting a new engine since it failed the vaccum test. Now the car runs great and I have no problems.

 

turns out i needed a tune up the spark plugs were shot and i just nedded a tune up now everything works great but i guess you had a bigger problem then i did but im glad you got it fixed

 

Blaze glad to hear it wasn't too big of a deal. Socket, whats the recommended mileage for tranny fluid change again?

 

this sucks my car is like back to the way it was before except it starts a little better but its still slow below 4gs and it shakes like it has seizures anyone have any suggestions ??

 

Get a vaccum test? Mine had the same issues and this confirmed my engine was bad. Good luck figuring it out though. Keep us updated.