Yes another P0171 thread
 

About two weeks ago I removed my VFAD and I capped off the valve under the throttle body. A day after the removal I got a CEL. Pulled the code and it was P0171 Bank 1 system too lean. Now the only thing is there is no difference in the way the car performs. It idles fine and im not getting any loss of power. YES i searched and found the probably causes are clogged fuel pump or vacuum leak. My car runs fine only real problem im having is clutch chatter and vibration when i release the clutch without giving gas. But that obviously has nothing to do with my CEL

Im thinking theres no way it could be my fuel pump because the car runs and idles fine. I cleared the code twice and it keeps coming back a day later. Im thinking i might have a tiny vacuum leak somewhere small enough that it doesnt give any loss of power. But are there any other possible problems that could be wrong that wouldnt affect the way the car runs? If it is a vacuum leak are there any common spots or hoses on the Rx8 that tend to leak.

I have a 2004 6speed Rx8 btw.

The leak doesn't have to be that big to pop that code. Do you have any way to log your LTFT? A small vac leak will have big idle trims....and will be relatively normal off idle

I would smoke test the intake and see if you have a leak......

If you were in there messing with stuff and got this code I would go back and re check your work. The leak has to be up stream from your maf.. a lean rotary is eventually a dead rotary it is a big deal.... I've been dealing with this for over six months and mazda has had my car for three weeks and hasn't found anything.

Unfortunately I dont have any access to anything to monitor my fuel trims. And ive went through and rechecked my work on the vfad removal once and couldnt find anything wrong. Does anyone know where i could buy an engine smoker to smoke test my intake? I really dont want this to go on and eventually kill my motor.

Cap the actual nipple on the UIM and see what that does.

I have seen 2-3 cars with that code with the VFAD nipple unplugged.....so it is a common fault. The plugs tend to fall out/off and you get a small leak. It could be a lot of places....Do you know anyone with an OBD2 scanner...or an AccessPort..that's all you would need to tell if it is just an idle trim that is causing the code

Noobish of me but i think i may have meant intake manifold instead of throttle body. Either way i pulled off the VFAD hoses and capped the only nipple that the hose was coming from. I took some crappy pics. I also took off the cap for the pics only it was on the whole time.

hey Kiwi,

thats hilariously insane: lol

Originally Posted by Mawnee
I will now be offering my Turbo kit to the public! This kit is capable of producing 900 crank HP. It is possible that I may have at one time in some way perhaps hit these numbers in my own car. I will niether confirm nor deny, nor comment on said numbers. However my kit may or may not, though probably not(though you could get lucky!) contain a turbo capable of these numbers.

sorry, continue with the thread.....

^Dont know what hes talking about. but I took off my accordion tub along with the airbox to inspect it. I put it back together and started it earlier today and now im hearing a loud hiss from behind the intake manifold and having a little loss of power. Im sure its a vacuum leak this time it sounds like it sucking in air really loudly. I just gotta find which hose is open. Hard to see since its coming from behind the Intake manifold. Ill try to get a video of it.

Think I figured out what was wrong. I touched the VFAD cap and realized that was making the loud hissing. Turned out my VFAD cap had a crack on it giving me the vacuum leak. I capped the nipple with some electrical tap temporarily and voila! hissing gone and a big difference in throttle response. Gonna buy some vacuum caps later on today to get this thing sealed off. Hopefully my CEL goes away soon.

Gotta use good quality caps..or they leak. :) Put a dab of RTV around the edge when you put it on and it will stay on great :)

u can always just use the cap from the LIM. Just buy one from Mazda for couple of bucks. They never break.