Zcashhh

Was driving home and suddenly when i got down my street my car loss power and died. When i parked it it still started up but it idles rough now and and makes pops in the 2-3k range and still revs up but it dies on cold starts now unless i hold the pedal for a min and still idles fine after warming up but once i put load on it its as if the throttle pedal doesnt respond right away its laggy. Ive changed coils, spark plugs, sparkplug wires, water thermo sensor, afm,ecu, ecu grounds and checked for vacuum leaks but couldnt find any kinda at a stump looking for advice or anyone thats experienced something similar key note is it backfires alot in 2-3k range and not so much after that and it still can get up to about 60mph slightly stepping on throttle i havent driven it since its happened and im not sure if it maybe is blown but it doesnt seem like it because it can idle very low without dying idk if that means much tho. I have 183k on the motor could it be blown already even without aggressive driving cause this has always been a reliable daily for me?

WondrousBread

To answer your question, it could be blown. Since you've done the usual diagnostics already I think it would be a good idea to do a compression test.

Don't jump to the conclusion that it's blown yet, but unfortunately your symptoms sound like they are describing compression loss. My car did the exact same thing when the engine blew.

For the compression test, get a regular piston compression tester or borrow from a friend. Gently unscrew and remove the little valve in the end (the valve sits inside the spark plug adapter side), then test both rotors. Remember to disconnect the EGI fuse so it doesn't start. Have a friend floor the gas pedal and turn the key while you watch the gauge.

You're looking for three even bounces above 90psi on each rotor.

A "proper" compression test requires the Mazda tool or using the conversion charts for pressure and cranking rpm, but this test is accurate enough to tell you whether the engine is blown or not.

FWIW, mine blew when I blipped the throttle in the driveway and it was only at about 2000rpm. If the engine is on its way out due to age / neglect (not saying that is the case for you), then it doesn't always take aggressive driving to do it.

Best of luck, report back with what you get.

Cardinell

Have you checked the TPS? That would cause a lot of what you're seeing. If you've maintained the car well, even at 183k, I wouldn't suspect a blown motor yet.

rlynchster

I was trying to do some trouble shooting in the past and decided to swap out my mass air flow meter out for a used one laying around in my garage. Needless to say the old mass air flow meter I put in caused some serious backfiring. I swapped it out back to the original one I was using.

Point being in my case, the MAF meter that was out of spec definitely had the ability to cause backfiring.

I would focus on the TPS, the water thermo sensor behind the water pump, and the MAF meter. Sounds like you already changed out the water thermo sensor. You can still get a rebuilt MAF meter relatively cheaply. . .. .A new TPS is kinda expensive. Or at least, more expensive than you want to pay for it.

I would then search for leaks or stains around the trailing injectors indicating air is getting past them.. .. . Inspecting the leading injectors is a bit harder due to the intake removal.

The backfire is going to be caused by too much air (O2) in the air/fuel mix. This can be caused by too much air, or said another way, too little gas relative to air.

A backfire should not be caused by a "blown engine" in my opinion.. . .That being said, a bad backfire at the wrong time can blow an apex seal so it's not something that you want to ignore.