This one's a doozy fellas. I like to think that Im pretty savy when it comes to the VQ motor, but this one really has my techs and I confused. The issue started with a mechanical over rev. This did NOT damage the motor; we inspected. No slight bent rods, etc. The only reason I mention this is to be all incusive, entirely. No codes, but the car putters [flutters] between idling revs and roughly 1500 rpms with slight revs (noise is not loud enough to over take sound of the actual engine, but lies right below it in my ability to hear it). Now, the car itself feels like it has an exhaust leak (checked this, no leaks) - loss in power overall more noticeably at lower rpms. The car has had art pipes roughly for a year and a half now, and stillen gen 3's for maybe 6 months. The car prior to the gen3's did have a slight tune - my tuner added fuel for the art pipes (maybe the tune isnt compensating for the stillen gen 3's...maybe not enough fuel? Feel like the Uprev tune + ecu would be able to adjust though). Hm...using Pennzoil Ultra Platinum for the first time < made engine more linear, and decreased throttle response oddly, but shot up mileage. Car is a '13 G37 coupe 6mt that I purchased new. Shes had Amsoil 5w30 until the UP oil. 49,000 miles now (I drive a lot). All maintenance is up to date. Throttle bodies cleaned. Need to clean filters for Stillens...but I really doubt this would influence this much throttle lag (drive by wire issue?)...havent changed the plugs...VVEL has been checked and is fine.

Thats all I have...haha if anyone has even the slightest inclination as to what may be going on, I would greatly appreciate the input!

Eric

 

Eric I am far from an expert but you were looking for ideas and I've had similier symptoms on a couple of my previous cars. Bad plug wires or plugs could possible cause a misfire. I owned a Mazda that used to go thru plug wires, they would arc to the engine. Just a thought. Good luck.

 

Thank you sir for the opinion. I did consider bad plugs...but i figured they wouls throw a misfiring code. I will pull them and see how they are. Thank you!

 

Eric, just out of a wild curiosity, what inspection was performed that was ascertain that the rods weren't bent?

ps. I'm not implying that they are, just curious.

 

I saw this happen on a Mustang. It was a bad ground on an electrical component believe it or not, and it took two days of screwing with to figure it out. No codes, just sputtering of the engine and no power. Just an idea to bounce around. It's hard to damage an engine component and not have a catastrophic failure of the engine.

 

You know, that's a very good question. I'm embarrassed to say that I did not ask for specifics. My dealership is very good to be. I suggested compression and leak down tests, but Jon...my master tech, insisted heavily that it wasn't necessary. He said that he spend a good amount of time on it with some hearing equipment. He came to the conclusion that it was not a bent rod. He actually that the sound may be some spring within the dual mass flywheel. Either way, he logged it within the database, to account for possible future issues...they'll take care of me if it does end up being a bent rod.

 

Hm...that's a very good thought. You have any ideas as to where I should start looking in the bay? LOL

You wouldn't happen to have the link would you?

 

No link to post, it was my buddies nephew's 'Stang, and we tinkered on it in his garage. I'd start with looking for your ground from the battery to the block. Have you had any work done on your car recently that would need the battery disconnected or wiring removed to gain access to other parts? Hope it's something stupid and simple. Electrical issues can be a true nightmare in diagnosing.