Foximus

Hey guys,

I have a 2010 with a 5.4 with an intermittent shudder. It happens mostly while in traffic, not moving, the truck will start doing this god awful shudder, like its misfiring, but no check engine lights up. All I do is pop it in to neutral, bring up the RPM, and its fine. I'm not running any after market parts, 100% stock. I'm wondering what could cause this? Coil Pack? Air issues? the filter is brand new... I'm able to re-create the shudder by sitting with my foot on brake, with the truck in gear, bring the RPM up to about 1k, hold it, then let it drop back down, typically it re-creates the shudder.

Thanks for the help!

techrep

iTrader: (1)

Mileage ??

Foximus

167xxxkm/103xxxmiles

Foximus

Forgot to mention, it always happens even when at normal operating temp.

tcp2

Your phasers aren't locking into place which is retarding the cam timing and causing it to shudder. You can recreate the issue by bringing the rpms up over 800rpm (which is the minimum when the VCT solenoids will start allowing oil through the VCT system and to "modulate" cam timing). When you let off the gas, the phaser springs should bring the cams back into static mode and lock the pin into place inside the phaser. This isn't happening and the intake and exhaust valves aren't opening/closing at the proper time.

It can be due to some sludging of the VCT oil paths, the VCT solenoids, weak phaser return springs, leaking chain tensioners(they are in the same oil path), blocked oil pump intake tube or any combination of the above.

A way to check it is, when it is happening (engine hot, etc) and you can re-create it at will, unplug the VCT solenoids at the front of the valve covers, then try to re-create it again. If, with them unplugged, you can't make it happen, you have one or more of the issues above.

Mine did it once while backing up while running very thin oil. I now run thicker oil and never had a problem since.