Aggielandpcrepair

I have narrowed this down to a few options I think could be at fault. I wanted to see what you guys have in mind . Were dealing with a 4.6l 2005 stx flareside I have a rough idle and no check engine lights or codes present. I have already replaced the tb assuming that was at fault because of a code which it did correct but the rough idle is still present. My next thoughts were to clean the maf and or (replace coils) or replace egr valve). I wonder if anyone else has solved this problem. I have used the search and found a variety of responses to these same questions. ANy help would be great.

Aggielandpcrepair

ps. the truck has about 98,000 miles. And was a one owner before I owned it. I got it at 90,000

Bigbucks243

I would check the coils for sure.

dereku

welcome to the 4.6 club. It shakes but is more reliable.

I have replaced everything on mine.

My next step is the fan belt and idler pullys cause they are in need or a replacement and see if that helps. but I replaced everything on mine with stock or better as it broke and it still shakes.

Bought mine with 89k and it has 112k now and runs like a top. A shakey idle top.

Only thing that seems to eliminate it is when I am in gear give it a little gas and raise the idle to 750-775 and it is smooth as glass.

Some of these trucks were turned down a little too low to meet emissions. Ford had a TSB for the 5.4 to remedy this just not the 4.6.

ophidia

I've replaced it all and mine's a little shaky too. The thing I did that made the most difference was added an Edge programmer and bumped the idle up 125RPM's. Smoothed it out a lot.

08Limitedford

I just bought my 08 5.4 a few weeks ago, cold start its rough then clears up when warm. But you can still slightly feel it ones its warmed up.

ford4wd08

How long have you ran it like that? I had a coil go out on mine and start missing like crazy, but it took a while for the CEL to come on and tell me it was cylinder number 5.

chris.c

I think its just a matter of the idle being a touch too low. If mine idles down it has an ever so slight rough idle, give it the tiniest amount of throttle and she smooths right out.

RLXXI

Probably worn out motor mounts letting the natural vibration of the engine transmit into the frame and thru out the rest of the truck. Motor mounts can be bad and not be torn to the point where the engine lifts on accel and drops on decel. Other than that you may need to replace missing exhaust anti-vibration weights, they hang from the pipes.



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dereku

Thats what those useless things are on the exhaust hmm. And motor mounts were on my list of things to replace too.