Ever so slight shudder at idle and when applying break...?

[NewbieVet]

Hey yall,

Looking to tap this pool of knowledge once again!

Wondering if I've got an issue here or whether I'm just not used to being behind the wheel of a V8 in a long time..

When I am stopped at a light with my foot on the break, there is a light shudder I keep feeling. I also feel it when I idol out of a parking spot in reverse, or if I idol forward (in a traffic jam or when picking up my g/f's kid at car circle). It doesn't last and once I'm moving it's smooth sailing and shifting.

Maybe I'm just being overly sensitive cause I just bought the truck? Thoughts / comments welcomed and encouraged! Cheers!!

J

 

[walnuts4x4]

I have read other forums about some F150s that have a slight shudder in idle... mine I feel every so often but it is only noticeable when I am watching the RPMs on my edge... it doesn't move on the factory tac... but it doen't affect anything on mine so I just live with it... almost to 100K miles on my 99...lol

 

[ELVATO]

I always assumed it was low idle caused by the IAC.

 

[NewbieVet]

any other thoughts on this? I need to decide if I'm going to take it back in....I want this puppy clean as a whistle before I start paying for fun mods (as opposed to needed engine work)

 

[designit]

B/E,

I "think" mine was doing the same thing from what you say... For me, it 'was' a cop or a cop to plug connection.

I also think (someone correct me) the cops are variable within a range for voltage? if so, my initial thought is the coil is worn in such a way that you get a slight misfire at idle until the rpms go up to push more current through the coil to the plug (weak spark on at least one plug)... (of course if coils don't work this way, I'm all wet - lol)

Long story short, I think I felt the same thing, changed coils around (swap out, etc) issue "AT IDLE" gone. -- But, I had at least 7 extra coils laying around when I changed out all 8...

Have you done any coil / plug work?

 

[Big Red Monster]

this is the exact same shit my dads Expedition is doing and were going crazy trying to fix it. i got a feeling we gonna end up changing all 8 coils

 

[designit]

Another thing I did (don't know if it helped?) was to put a shot of MAF / electrical cleaner on the electrical contacts of coils and injectors.

Also had a slight buck at idle 'after' I changed coils... so I removed coil, pulled the plug, checked gap, reinstalled etc... Could have been that I had a bit too much grease on the boot? (not sure on that one).. I just kept pulling, cleaning, swaping, re-seating & it went away...

 

[Big Red Monster]

maybe were going to try that today because so far we changed 2 coils and the shudder is still there, its a ***** to remove the coils on these engines though, theres so much stuff in the way

 

[NewbieVet]

sure as sh** hope its not the coils cause I'm not a technophile so would need to have it done professionally which costs mucho $$$. Assuming I'm not doing any damage by leaving it alone and seeing if it gets worse??

 

[designit]

even on a couple of the old coils I put back in, I cleaned out all the old buildup of gunk on the coil spring... Removed the boot, sprayed it with maf cleaner & ran a toothbrush around the end of it where all the old dielectric grease / rust was... (common sense kinda stuff) You'll find it...

If you're not changing coils, maybe it's a good idea to pull the fuel rail, on one side at a time & clean all the crap from the coil spring & elect. connectionis... (of course if you're going to do that, change the plug at least, that's pretty cheap.)

Anyway, I think it's just weak spark @ 1 or more holes.

Good luck.

 

[designit]

sure as sh** hope its not the coils cause I'm not a technophile so would need to have it done professionally which costs mucho $$$. Assuming I'm not doing any damage by leaving it alone and seeing if it gets worse??

You don't need to be... But the choice is yours of course.

you could practice on the 1/2/3/5/6 holes.. Just have the right tools and a torque wrench (harbor freight $10.00) & if you've never worked with a torque wrench before, practice on another bolt somewhere (trailer, bike, etc...) to get the feel of it... You'll likely need a breaker bar, a couple of extensions & a universal joint too...

 

[NewbieVet]

designit,

Wish I was a techie. So envious of all you guys on here who do work on your vehicles..maybe one day I'll learn this stuff, but as of right now i struggle to change a door nob when it falls off! Pretty much everything you said above is like Japanese to me! Breaker bar? Extension joint? Hell, I wouldn't know where the plug are on the vehicle! I'm ashamed! Anyone who wants a free weekend of drinking beer, fishing at a nice place on the water in St. Pete is welcome to come visit me and teach me the Jedi ways!!!

 

[designit]

Yeah, I too was as nervous as a ***** in church with this stuff (umm, about 100 posts ago, lol) -- there's a thought, post like a madman in the 'post *****' thread & maybe the lightbulb will come on?

And isn't St. Pete in Russia or something? lol..

 

[Soldier777]

You might have bad motor mounts, or they are starting to go bad.

 

[NewbieVet]

St. Pete FL (=

Bad motor mounts? what are those??? jesus this is scaring me now!

 

[Soldier777]

Motor mounts mount the engine to the frame and help reduce vibration. all I am saying is the shutter might just be a little vibration.

 

[NewbieVet]

Am in my expy right now waiting at the airport. Can't tell if I'm just overreacting or if there's an issue. Seems to be maybe it's just the natural vibration of the engine. The steering wheel (well maybe the entire truck) seems to vibrate a little bit. Think I might just be going nuts....

 

[walnuts4x4]

going "nuts"???? lol join the crowd...

 

[NewbieVet]

going "nuts"???? lol join the crowd...

Thanks everybody...he'll be here all week!!

 

[panda24619]

its most likely nothing. my engine idles a little ruff sometimes. then goes away. if it doesnt get any worce its fine. just watch your mpg. if it gets worce then you know something is up. if not and the ruffness doesnt get worce your fine. dont stress any more!