Got A Major Problem
 

got a problem...my car wont pull past 4500, feels like its being dragged back after 3000, spark knocks at WOT, and i keep getting 0302(i think)-misfire cylinder 2....i have changed the coil, the wire, the plug, and the injector...still the same symptoms, still the same code. car idles smooth, and runs ok until it gets above 2000 rpms....ANY SUGGESTIONS???:bang:

Change the O2 sensors and clean the MAF.

if the O2s were bad, wouldnt it throw an O2 code?

id get some of the MAF cleaner and change your front 02's and your fuel filter

ok...WOULDNT THE O2S THROW A CODE?????

sometimes it takes a while to throw a code

Mine never threw a code but I had the same symptoms in July this year. I thought the motor was toast because it wouldn't go over 4K.

o2s usually only throw a code if their giving bad voltage or if they're totally toast...9 times out of 10 they're bad without throwing a code at all

O2's trust me!!!!!!!

Do you have the stock exhaust on it?

the converters could be clogged.

You could've had someone/someplace diagnose it for the trouble you've had.

A real scanner could show you fuel trims/02 counts/maf readings....etc. and if it's running that bad it probably would've been an easy diagnosis.

Can you take the O2's out all together and still be ok? I have an ORY and race version headers, I wasn't planning on putting them back at all. Sorry :hijack:

Check the fuel pressure and volume see if it is dropping severely under WOT.

I had the same problem last month.
try checking your MAF cause i've changed mine and it all worked fine :)

How does the car behave when cold? In the first few minutes (before the car goes to closed loop) if the car acts funny then its probably NOT the O2 sensors. If the performance issues arise after about 5 mins its probably the O2s.

Since your issue is happening around 4000 RPM I would check the MAF first. The MAF is the sole source for air calculations past 3500 RPM. Disconnect the MAF and see how the car runs (caution you'll get a check engine light doing this). If it run OK then its the MAF.

To answer your question, yes you can run without O2's but you'll need to get an open loop tune.