04 MT K&N intake and Greddy exhaust. Recently replaced coils, plugs, wires, coolant tank, and apv actuator, and all computer updates. Now engine is popping and crackling at 7000rpm+ under hard acceleration and feels like it has loss of power too. Took it too dealership and test drove with the head guy and he confirmed that it was doing this. Had them compression test the engine here are the results: Rotor 1 kgf/cm2- 8.7, 8.2, 8.5 at 238 RPM. Rotor 2- 9.3, 8.1, 8.7 at 248 RPM. Thats exactly what the sheet says. Checked for exhaust leaks and found nothing. They said theres nothing wrong with the engine and can't figure out why its doing that. There's clearly something wrong. They did say however I could take it somewhere else and if they could diagnose the problem then the dealership will fix it as its under warranty. But, before I bring it somewhere else, does anyone know what is causing this?

 

Sounds like a toasted cat, I had trouble with 7k+ rpm rev climbing smoothly. Gutted the cat, all is well now.

 

Another guess - plug wire(s) not properly seated at either the spark plug or ignition coil end of the connection. Might be close enough contact that arching keeps things going under minimal load but not under heavy load. Certainly makes a sound when arching that could be described as popping and crackling...

 

Sounds like you have the Rice Krispies engine mod.

 

They said the cat is good and no exhaust leaks.

 

The mechanic checked all of that and even replaced the plugs which were already new. I'll check again myself though cuz thats a good theory.

 

Did they remove the cat and checked the honeycomb or just check for error codes from computer? Need at least a visual to confirm and some cats still failed even-though the honeycomb is looks intact.

 

Not sure. They just said the cat was good. Im taking it to a local mechanic this is bullshit.

 

Ha ha... the is no code for a bad CAT.

Only way to tame it is to take it off and look inside.

 

Cat performance below threshold, perhaps? What is the 420, CEL?

In any event, we all know what the fix is........

 

Yeah the cat was my first guess but it sounded more like it was coming from the engine but its hard to tell. The dealer also said the cat was fine when they replaced coils, etc. Before I brought it in this wasn't an issue, there were no sounds. Then 2 days after I get my car back I get this? Can a cat go from being perfectly fine to gone in that short period? I didn't even whale on it. I'm really starting to believe this dealership screwed with my car or just screwed up in general and is trying to cover it up. Because it's just been one thing after another with this place...Can you recommend some good aftermarket replacements that will pass emissions if it is the cat?

 

The factory ignition coils become weak over time, as often as 30K miles, and when they become weak they start to take the cat with them. Since the OEMs treat warranty claims in much the same fashion as the federal government treats Medicare/Medicaid claims, I do not blame the dealers for not wanting to be proactive with matters like these. Should Mazda decide to not cover something under warranty, the dealer is left holding the bag.

 

Do a search on marbels in a can.

you may be describing this.

 

So I took the car to another mechanic and they determined that there is a mode 6 misfire. They say the new engine may be bad but say I have to replace coils, plugs, wires in order to make an accurate determination. I just had all of these replaced not even 1000 miles ago! I noticed this issue within a week of getting my car back from the dealership. No way they went bad that quick! So either the dealership ripped me off and never replaced these things and the new mechanic legitimately feels that this may resolve the issue and/or the new mechanic knows the engine is bad and is just trying to get $600 out of me. Sucky situation. Does a mode 6 misfire code mean the engine is fried no matter what? What do you guys think?

 

The new coils you obtained from the dealership are warrantied. Take it back to the dealer and tell them your getting coil misfires again. They should warranty them. Or get the BHR ignition kit and be done buying and worrying about ignition coils fir a very long time.

 

Is this warranty transferable between dealerships? Because I don't want to take it back to the original place. I don't even want them eyeballing my car. Does it only cover the coils? Is that really the only issue..the coils? Because they recommended replacing coils, plugs, and wires. Thanks.

 

Ok so I called corporate because this situation was just complete bull. It was determined that the mechanic at the new dealer was basically trying to screw me over and get me to pay another $700 for the coils, plugs, wires when he new they were covered under warranty. He was just pissed he had to fix someone else's prob. Can't say I blame him for being pissed but thats still his job and they are taking my business from the other dealer. Anyway, the cause of the popping was due to a loose spark plug and a large amount of carbon buildup (due to loose spark plug) on cylinder 2. So he supposedly fixed this and now its not violently popping from 5000+ rpm but moderately from 7000+ rpm. They told me its due to my K&N intake and Greddy exhaust. They said with those parts I have to upgrade the ignition system. Does this seem accurate? I know the stock ignition system sucks but I can't imagine this engine could be so sensitive that an intake and exhaust could cause misfire. Plus, even with the old blown engine, as shitty as it drove, it still never misfired with the intake and exhaust. Maybe due to low compression there just wasn't enough power to do it? Maybe the loose spark plug and carbon buildup caused permanent damage? What y'all think about all of this?

 

Replacing the stock exhaust you will hear some things that you are not used to. If you had carbon buildup it is possible that it is still working its way out of your system and you could try and help it along with a seafoaming. If you are running a stock cat you should slap a midpipe on just so all that crap that blows out doesn't get stuck in your cat and cause other problems. And since you're questioning the health of your cat anyway...don't risk it.

 

Did they do a decarb? Has the engine stopped going "snap crackle pop"? I'm curious if carbon buildup (even if decarbed) can cause long term damage to the engine or seals as well...