OH NO!! not another misfire thread!! lol

well yes and no folks.

its like this, my problem with the 2002 V6 arose with just a misfire that went away but then returned and stayed.

after researching all of the available material on here i have replaced the coil packs and spark plugs and i have also cleaned the IACV and checked the manifold gaskets.done the cat converter also. plus all of the hoses and wires etc have also been checked. i cannot see anything worn or broken, cracked or damaged.

still runs rough.


here is the thing that i have not heard from anyone with a similar problem, when i start and run the engine in park, it runs rough and when i try to rev it, it doesnt go past 4000rpm...it just hits a limit and bounces off 4000rpm.
i have tried to road test it and the same thing occurs, no power at all and it wont go past 4000rpm.

a CEL did come on once while idling in the driveway but has gone now.

PLEASE HELP ME!!!!!

i thank you all in advance

 

Rastus: I am guessing here.

1. Cam position sensor: look for Youtube: how to test a cam sensor
2. What exactly did you do to the catalytic converter?
3. Timing may have jumped.
4. Is there an IMRC system on your engine? It may be stuck.
5. Test the throttle body position sensor. (Youtube)

Let us know what you find and please put your vehicle information in your signature, including mileage.

 

READ THIS AFTER LOOKING CLOSELY AT YOUR EXHAUST LAYOUT UNDER THE CAR:
https://www.mazdaforum.com/forum/maz...-design-28940/
I would change the dreaded PCV valve and possibly O2 sensors.
Mileage? Clean the MAF?

I do not envy your position. Good luck.

 

Thanks for the responses guys,

I have taken the cat off and run it to see if that would make a difference to idle misfire but it didnt. when the cat was off it was obvious that it was badly needing replacement, so i put a hi flow on it, started it and still misfired.

it has 170,000km on the clock.

i will do the PCV and look at O2 sensors also.

Thanks to UseYourNoggin for that informative Exhaust link...man they screwed that up!!! i will be making the same mods to mine

and @ tanprotege, i will check timing etc and TB position sensor

Thanks guys!!

 

Can you get a fuel pressure reading?

 

My parents tribute also hits a limiter of some sort at 4000rpm or so. It will rev past that when actually driving though, maybe they're two completely isolated issues? My parents doesnt have the coil issue...yet haha

 

There is no limiter @ 4000 rpm on a gas engine!
However the VVT (variable valve timing) does kick in for more power around that rpm!
Could be Oil Control Valve. A solenoid valve regulates both the volume and direction—advance or retard—of oil flowing through the VVT-i controller. The ECM adjusts intake valve timing by varying the duty cycle of this solenoid valve, which is called the OCV (oil control valve).

 

well folks,

took it to the mechanics to get the diagnostics done...turns out its misfire is on cylinder 1 and 3 and its due to a faulty PCM. uugh..not what i wanted to hear.

Thanks for the help people. i think i may just go soak my head in a bucket of water now....then phone the bank for a loan LOL

 

Rastus:
Car-Part.com--Used Auto Parts Market

and:

 

That sucks. That's the last thing we would do before anything else (computer ECU).