Cx7 missfire cylinder 2

Tang.38

Member
:
Mazda cx7
Iam a new member I got a misfire with cylinder2 on a 2007 Mazda Cx7 with 140000 km .changed spark plugs and coils around made no difference and code reader still says misfire cylinder 2 (p0302) and dealer recons it's a coil maybe different cylinder not that one but plug isn't firing properly black and the rest are clean ish even with coils changed around thanks in advance
 
To up date ...checked compressions 150 PS across all cylinder and with engine running I've reached under inter cooler and lifted coils off of plug cylinder 2 doesn't make any difference pulled manifold of and checking injectors . Responses please if not injector what next?????
 
To up date ...checked compressions 150 PS across all cylinder and with engine running I've reached under inter cooler and lifted coils off of plug cylinder 2 doesn't make any difference pulled manifold of and checking injectors . Responses please if not injector what next?????

150 PS, sounds a little low to me? What is the desired spec range?

For me, I would crank over with a spark tester on #2 and verify visually that you are seeing a spark on that #2 plug when cranking. If you got spark, then it is down to fuel and air being one of your problems.

As far as fuel, since it is direct injection, the injector seals will also cause an individual cyl misfire. In some pictures I have seen, there has been residue underneath the injector, on the cylinder head/block where the failed injector seal exists. (detect)

As far as air, an individual cyl misfire can be caused by a sticky or heavily carbonized valve, not allowing for proper valve seal.
 
Last edited:
I'm having this same issue on cylinder 2. Shop replaced spark plugs, replaced one of the coils (apparently the coil needed replaced, but misfire continued to happen a day after it being fixed, did a fuel clean out. Might have it looked at again at another shop but am continuing to look myself to see what else i can find. Car has 82,000 miles.
 
it's probably a fuel injector. look into these culprits as well:

Faulty oxygen sensor(s)
Faulty fuel injector
Burned exhaust valve
Faulty catalytic converter(s)
Defective computer

Read more at: https://www.obd-codes.com/p0302
 
Back