Help! rough idle, whistle when accelerating, slight backfiring , CEL codes
Thread Starter
Racer
Joined: Oct 2017
Posts: 319
Likes: 18
From: Florida
Help! rough idle, whistle when accelerating, slight backfiring , CEL codes
Hey guys ,
Looking for a recommendation on where to start with my 2014 z51 m7, No warranty . I bought it tuned by a company in chicago with an MSD airfare intake manifold, haltech CAI, runs e85 kit, ported throttle body and both cats deleted ( CEL deleted for this by tuner )
Last few weeks its been running rough , I get check engine code P0171 / P0174 (system too lean)
Symptoms
- Idle is rough , sometimes its perfect and sometimes rough,, 50/50. When driving its smooth as silk. It hasn't stalled on me but it'll drop up n down between 700-400 RPM while sitting in place and you feel the car vibrate. Also sometimes while at a red light / full stop the RPMs shoot to 2000 while at a full stop on its own then drop back down
- I hear a whistle type air noise, when accelerating over 2000 RPM, only when accelerating.
- Yesterday for the first time while driving , i let of the gas and heard a little exhaust popping, nothing serious but it crackled a bit
Now I'm getting concerned. I personally think its a vacuum leak of some sort after doing a ton of research . I took it to a mechanic and he says its from the tune that was done before i bought it but he didn't run a leak test.
Should i take this to a tuner? chevrolet ? or a mechanic . Any input or ideas that can help. I just want to fix this this .
Looking for a recommendation on where to start with my 2014 z51 m7, No warranty . I bought it tuned by a company in chicago with an MSD airfare intake manifold, haltech CAI, runs e85 kit, ported throttle body and both cats deleted ( CEL deleted for this by tuner )
Last few weeks its been running rough , I get check engine code P0171 / P0174 (system too lean)
Symptoms
- Idle is rough , sometimes its perfect and sometimes rough,, 50/50. When driving its smooth as silk. It hasn't stalled on me but it'll drop up n down between 700-400 RPM while sitting in place and you feel the car vibrate. Also sometimes while at a red light / full stop the RPMs shoot to 2000 while at a full stop on its own then drop back down
- I hear a whistle type air noise, when accelerating over 2000 RPM, only when accelerating.
- Yesterday for the first time while driving , i let of the gas and heard a little exhaust popping, nothing serious but it crackled a bit
Now I'm getting concerned. I personally think its a vacuum leak of some sort after doing a ton of research . I took it to a mechanic and he says its from the tune that was done before i bought it but he didn't run a leak test.
Should i take this to a tuner? chevrolet ? or a mechanic . Any input or ideas that can help. I just want to fix this this .
Racer
Joined: Oct 2002
Posts: 473
Likes: 54
From: Addison TX
Definitely sounds like an air leak and I personally would NOT drive it until the problem is resolved! You're running lean which will cause engine damage.
Try spraying starter fluid around your throttle body, Intake manifold, etc.. When you engine speeds up you've found your leak.
Try spraying starter fluid around your throttle body, Intake manifold, etc.. When you engine speeds up you've found your leak.
Melting Slicks
Joined: Aug 2016
Posts: 2,762
Likes: 1,017
From: MOUNTAIN HOME Arkansas
I know this sounds risky (did when I was told) but called 3 places & looked up on Google, so OK. Use a small, like 16 oz., propane bottle with plastic tubing. Just barely open the valve while moving it around the areas of suspected leaks till rpm rises-Wa_La! It won't leave a mess either like using some types of sprays.
Drifting
Joined: Jul 2016
Posts: 1,481
Likes: 394
From: Virginia Beach Virginia
The engine really never idles smoothly. Rather powerful engine so getting a smooth idle at 800RPM's is tough. Add in tuned to run on ethanol and there you go. Get it tuned back to stock and things will clear up.
