Weasel935

Hello all, as the title says I'm new to the site but I thought I'd subscribe and get a few opinions about what I got. First things first, I've got a 2014 coyote premium. So far I have the JLT cold air intake, lethal offroad X-pipe, MBRP 3'' catback exhaust, 2 JLT tunes (one race with "cammed option", one street with normal idle) and the Barton 2-post shifter bracket. Car has just under 17k miles, Mobil 1 synthetic oil changed religiously, only gets 93 non-ethanol fuel. Never abused/raced/beat on/whatever. Obviously the car is quick and fun to drive so I let her stretch her legs on occasion but ONLY once the car is warmed up. That being said, I'm very familiar with cars/bikes/trucks and so on, and used to twist wrenches for a living so I'm definitely not a new guy when it comes to engines. I was running my cam tune for awhile because it sounds great and is very aggressive but I recently loaded the street tune for fuel economy and ease of driving in traffic. Now the problem. I have noticed a weird rattle type noise coming from the intake with the engine under load, any gear, starting at about 3700 and lasting to about 4100 RPM's. The noise almost sounds like a Honda engine when VTEC (yo) engages. Definitely not predetonation and I can't imagine it'd be piston slap. Won't do it when it's in neutral so I don't suspect bearing failure. I'm wondering if its just induction noise? The intake is loud, but this noise seems too...mechanical?... if that makes sense. Obviously the dealer is out of the question because of mods and this noise is just driving me nuts! Sorry for the wall of text and any help is much appreciated.

jwog666

noises are impossible to diag over a forum, it could be any part that moves.

Weasel935

I get that for sure. It just seems strange after I put the JLT intake on now I hear something weird. I'm gonna assume it's the cams changing position and altering the induction sound until spontaneous self disassembly lol.

jwog666

maybe check over everything you touched to make sure nothing was left loose or is making contact. but you might be on the right track, could be just how that intake sounds now.

Weasel935

Will do. I'm also gonna load the other tune to see if that makes a difference. I really don't wanna go back stock and try the dealer for a motor....

jwog666

i have yet to see any internal issues with the coyote roll in where i work. so i suspect its not an internal problem

Weasel935

Cool. May be paranoia, if I stab it while it's making the noise it goes away. I never would've heard it had I not had the windows down today. Thanks for your help though.

P51C

With all due respect, there is no such thing as "predetonation". Any time detonation occurs it is incredibly destructive.

The rpm range you say the noise is occurring...are you matting the throttle fully to hear it or is it under light/mid throttle. Are you a stick car or automatic?

You could just take 15 minutes and slap the stock airbox on and see if it changes it, obviously it won't exactly run perfect but, it might help the diag.

Weasel935

What do you mean no such thing as predetonation? Predetonation/preignition/spark knock is fuel lighting in the cylinder before its time to (spark plug lighting it) and creates a horrible rattle noise. This is why we have knock sensors now. And yes it's very destructive. That's what I've always heard it called anyway, but that's besides the point. It does it about half throttle and if I make a drastic throttle change it stops, even while it's still in the RPM range. It's been my long week at work so I haven't had time to change tunes or air box but I'm almost convinced it's just induction noise. These engines move an incredible amount of air and this intake absolutely screams when you put your foot through the firewall on the interstate next to a concrete center divider lol. I really appreciate your help guys, and keep the info coming. Can never be to cautious about an engine like this.

P51C

It's your terminology. It's not Predetonation, there is no detonation event it is occurring in front of that is a natural product of combustion. It is called detonation and can occur at almost any time in the combustion cycle. It's never good and I am surprised I'm having to explain this to someone who turns wrenches for a living, by his own description.

True spark knock will not be occurring at anytime under part throttle. If you are getting things that sound like spark knock at anything other than high load, it's likely something else. A flash of it can occur at the transition between light and high load though and Coyotes can tend to this. A particularly sensitive rpm range is 4-4500 rpm, under high load.