99 mazda protege pop noise!

code is po171- running to lean in bank 1

ok guys i have a 99 protege and it sometimes has a slight pop at idle (warm or cold), each pop will raise the rpms to just over 1k then back down. when i lift off the hose that connects the air filter to the throttle body i can hear it wayy louder(sounds like popcorn). my engine and intake have been smoked and theres no leaks. ive replaced battery, replaced spark plugs, had my throttle body taken off and cleand and even replaced the o2 sensor! and still cannot determine the problem anyone know something?!

I'd still say there's a vaccum leak for that code on a Protege!

thanks, but i witnessed my car getting smoked out for leaks, checked all seals too, im thinking it might be the fuel filter/pump? its getting worse and worse.

I know for a fact that alot of fords don't recognize smoke testing as accurate for pinpointting vaccum leaks because they'll have what they call calculated leaks where the smoke will always come out. ie the irmc shafts on the Windstars. So that's why i'd question the accuracy of it. As well intake gaskets can leak only on a hot engine as the metals expand so if it's always being smoke cold it's somewhat inconclusive. Lastly alot of Mazda's had issues with intake gasket leaks but as always it could be the fuel pressure, O2 sensor, MAF sensor, map sensor, coolant sensor, etc. all of which are worth trying instead of going with the pattern failure that I suggest.

that duct you are grabbing and pulling...make sure that it is not split they crack alot esp. on the underside..this will cause lean codes.