scottielovee

Hey guys I cannot for the life of me get my ep3 to stop throwing code po172. Runs like crap in low Rpms. Runs great In the top. Iv tested fuel pressure, the rear o2 sensor. Changed the cat and I'm stumped. Any help please.

05hondacivicep3

Ok you replace all of those without diagnosing the issue? Did you check for vacuum leak? Hows your upstream o2 sensor ? Whats your short term fuel trim? ?

scottielovee

No I just had them checked by the shop during the diagnosis, I have checked for a vacuum leak and I don't know how my upstream is. I'm about to break down and replace it. But I don't wanna throw money at parts. The shop said they think someone put after market cam gears in it and it needs a tune but it's weird they said that because they didn't remove the valve cover..

scottielovee

The only part I changed was the cat. I changed it out with a high flow cat cause when I bought the car it had a test pipe.

05hondacivicep3

Dont ever go back to that shop again they dont know what the f are they doing lol. To start check for vacuum leak , pour some water on the throttle body ,vacuum hoses ,intake manifold where the head and IM meets and see if the idle changes and report back
. next buy yourself a little scan tool like this one http://www.amazon.com/gp/aw/d/B0050V...vyL&ref=plSrch works great and fast (youll be suprise what this little scanner can do )

scottielovee

I checked vacuum leaks with carb cleaner. Sprayed it everywhere and no change in idle. I really think it's my upstream but it's 180$ for an aftermarket oem equivalent

scottielovee

Someone said if I'm lucky I'm lucky enough to find it in a junkyard I can use the upstream from a em2? Sound right?

scottielovee

Ur link won't load. What's the name of the scanner so I can google it?Also it's worth mentioning that sometimes my check engine light will stay off for about 2 days or roughly 5 hours of drive time. And then come back on if I unhook the battery to reset the code

05hondacivicep3

Ok , then you need to buy that scanner its called launch creader v or vi at amazon(40-60 range) depending on how much money you want to spend on it so you stop removing your battery terminal to reset a light (which is bad imho) or just unplug the ecu fuse @ the fuse box.

Hows you mpg lately? Without seeing those stft (short term fuel trim) and ltft (long term fuel trim) i cant really tell you whats wrong with it , but im leaning towards your upstream o2 sensor because that controls the A/F ratio on your vehicle

05hondacivicep3

Dont get a used one bro buy new , check rockauto.com

scottielovee

I'm going to look into buying an upstream today and il report back

scottielovee

I replaced the upstream o2 today same issue..