Ever since I've had my car, it's back fired at low rpms, so I have to keep it past 2k or it'll back fire and this sucks my MPGs down to crap. So here's my specs:

'00 Prelude SH
AEM Cams
AEM Fuel Rail
MSD-I Ignition
Custom Exhaust
CEL is throwing a rear O2 code.

friend of mine told me that the MSD igintion could be doing that - so I went and bought a factory OEM Ignition and still did the same. Someone told me the Fuel/Air could be set wrong, I fixed that and still the same. I replaced both O2 sensors and still the same code. So the only thing I haven't tried yet was Timing. Could that be it? If so, how do I go about setting it? Thanks in advanced.

 

-What 02 sensor did you buy? OEM or vatozone BS
-Check your timing with a timing light

-And umm I dont think you have AEM cams...maybe cam gears

 

Yeah, gears, sorry.
I bought Denso O2's

 

Sonds like its running really rich or the timing is advanced to far...or a combo of both...

What do the spark plugs look like? They should be a light tan color

 

They're solid black. so is my back bumper

 

does it have an adjustable Fuel pressure regulator ? such as an AEM,B&M,etc...
if so check the fuel pressure with the vaccum hose removed and see if its in spec with the manual. This could also be a result of an incorrect o2 sensor,or a faulty injector thats stuck open,

 

Custom Exhaust?, do you have a cat?