Alrighty, I've noticed my truck doesn't seem to like idling in drive very much, there is an annoying humming sound coming from the front end in drive when I sit at stops or do a rolling idle. There is also a noticeable vibration while stopped in drive, and it almost feels like I'm sitting in a massage chair at times. This doesn't happen at all in nuetral/park.

I'm driving an 08 F-150 5.4L with 35" tires, 4.56 gears, and 3.5" AF1 intake on a X3 from Justin at VMP. My truck only has 3000 miles, and I've been running the 87 perf tune. I recently switched to the 87 mileage tune and there seems to be a noticeable improvement in less sound and vibrations, but are still quite noticeable. I'm planning on letting this tank run down and fill up with 93 octane to try out my 93 perf tune within the next week or so.

Question is, does this have to do with my drive idle being so low? I only idle in gear at around 525rpms while I idle near 750rpms in nuetral/park. It really sounds like my truck might be thirsty, as the sound/vibrations go away anytime I give it gas and rev up aboce the 525rpm range.

I e-mailed Justin to see if I could do some datalogging, but I'm just curious If anyone else has had this problem or something similar while I wait to hear back from him?

 

I'd think the MAS is near it's limit idling that low and with the 3.5-inch. I had idling issues with the 3.5-inch that even bumping the in gear idle to 750 didn't completely take care of on a hot day. Ended up going to the 3-inch and never looked back.

 

Just email him and he'll fix it.

 

I will take a look at your email and get back to you.