Dragster Posted October 24, 2016 Share Posted October 24, 2016 have a '95 pathfinder SE, been running great, but today i heard a slight backfire thru the exhaust when lifting off the throttle. i cleaned the MAP sensor, timing checks out good (holds steady timing), but also noticed a drop in gas mileage. all feedback is appreciated. Link to comment Share on other sites More sharing options...
LittleFR Posted October 24, 2016 Share Posted October 24, 2016 Bad gas? Kind of sounds like CAT is stopping up from oil consumption or bad fuel. Link to comment Share on other sites More sharing options...
RCWD21 Posted October 25, 2016 Share Posted October 25, 2016 Bad gas, dirty injectors, bat cat causing an issue. It could be several things. Does it do it every single time you drive and take your foot off the gas? Sent from inside my potato Link to comment Share on other sites More sharing options...
Dragster Posted October 27, 2016 Author Share Posted October 27, 2016 the back fire is not loud, but I always hear when decelerating. I sounds like it's coming from the engine sometimes, but most times it's from the tail pipe. this morning it starts to 'surge idle' when at a stop. Timing checked, MAP sensor cleaned, Lucas additive in gas tank. No check engine light, but will have that checked anyway. any ideas are good. Link to comment Share on other sites More sharing options...
RCWD21 Posted October 27, 2016 Share Posted October 27, 2016 Have you checked for vacuum leaks? Any unmetered air after the maf can cause idle issues because the computer doesn't know what to do since there's extra air but the throttle body is still closed, so it tries adjusting the fuel mixture adding to the surging problem. When you drive like this the oxygen sensor is getting one reading while the ecu is telling the engine to do something different. Check and replace all of your vacuum lines if you haven't already and also check the tube between the air box and the throttle body for cracks and splits. Sent from inside my potato 2 Link to comment Share on other sites More sharing options...
Dragster Posted October 29, 2016 Author Share Posted October 29, 2016 Found crack in Intake Tube near TB. Temp tape fix for now. Replacing all Vic lines today, maybe also the O2 sensor. There's no CAT, just straight pipe. Link to comment Share on other sites More sharing options...
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