heres the situation, buy a new truck all is well, even my mechanic looked it over and no problem few minor things and a slightly rough idle "its prolly plugs, wires filters etc." Change fuel filter, all is well but still have a bit of a rough idle. Change plugs/ wires and air filter (K & N) all is well. drive round all day then BAM, "service engine soon." needless to say i was like WTF! so i hit up autozone, and get the DPFE code, ok no buy new part move on right? NOPE code is still there. all the while im woking on this truck and hear this random knocking comming from the passenger side rear of the motor. Now i know its not likely to be rocker arms, rods, or anything of the sort as its not even close to constant. its kind of like an AC compressor kicking on or something time wise (the ac is not on). then i begin to notice the clutch fan surges now and then, ok so maybe the springs are going or something. So far all i have done is fill the tank with 89 put in a can of lucas fuel treatment/ cleaner put some lucas in the tranny, and put some lucas in the engine, and out of frustration used a can of seafoam (halv sucked in via the PCV and the other half in the crankcase) ive used seafoam many times before with no problems. i know everyone has their opinion about the stuff but on an engine with 50,000 miles im not gonna loosen up that much sludge.

my 1999 4.6L F150 needs your help...

 

well alot of that noise will be normal from many things, but i doubt it has anything to do with the rough idle. Did you clean the IAC or MAF sensor?

 

maf sensor yeah, IAC no. forgot to mention it idles around 600-700

 

did the idle go lower once it started to idle rough?

 

no not really, ive never seen it drop below 550ish and never really went above 700.

 

so the idle speed is normal then. Just clean the IAC and check for vacuum leaks. spray carb cleaner around the engine on all the vacuum lines and if it revs up, you found a leak. Be careful though

 

becareful as in, dont spray carb cleaner on the exhaust manifold so i dont burn my eyes and run around screaming cause it burrrrrrns? or careful like dont spray the fan and get sprayed in the face? LOLOLOLOLOL

any thoughts on the fan issue or the random knocking?(im currently on search page 17 for knocking...)

btw thanks for all the help man.

 

You need to settle down a bit and keep from working yourself into a frenzy.
1. Did you not road test the truck long enough before you bought it to see what noises you might hear?
2. You never mentioned the code that was read and what was done about it or I could not understand what you wrote about it..
3. The fan clutch is supposed to cycle as the thermostsat opens and closes.
4. A 50k expect there to be some things you might notice.
5. Don't use additives unless there is a need to address some issue than 'might' be helped from additive use.
Don't get upset with me but you need to hear a different tune, at times.
50k mileage is still a new motor. considering they go well past 150k all the time.

Likely the fuel commanded by the PCM Is on the lean side, making the motor less than as smooth an idle as it could be.
All these other things arn't going to improve it as you found out.

 

i drove it for about 3 hours before i bought it, then my mechanic drove it for 20 mins put it on the lift and looked around lowered it and we both listened to it idle for abotu 5 mins.


the fan thing is happening every 10-20 seconds which is why i say its surging. if what you are saying is true it sounds as though i need a new Tstat. if it is a lean condition with no codes showing how can i correct that (91-93 octane?) 0401(maybe it was 0410 cant remember) was the code said "egr flow insufficent". after a lengthy search of this forum i found the DPFE sensor the be the culprit. so i replaced it.

it may sound like im upset, but im not. i a bit adgiatated though...ive had the truck all of 5 days now. if i need to jump down the dealers throat i dont have alot of time.

 

I had the insufficient egr flow... I cleaned the throttle body ports that lead to the egr. They were completely blocked with crud. Drove the truck for 10 mins and the code cleared all by itself... hope that helps.

 

You was lucky on the 401 code. It could have been another part of the system.
The rough idle, if it is leaness, is a program controlled setting.
The best that might be done is firmly ask the dealer service rep to look up a possible PCM reflash for the problem or take care of it in some way.
It's not an fuel octane issue.
A tech could hook up his scan tool and look at the values for idle and tell if it is the problem by compaeing the value to limits.
Good luck.

 

ok thanks for the help. after some searching it looks like tomorrow im going to have to rip out the throttlebody and EGR and shoot 2-3 cans of carb cleaner through them. another search revealed one possible problem related to a coil pack having a bad tower on it. the one prospect that is kind of scary is the coil packs may be going bad. on the good side of that autozone sells some nice accel ones for about 84$ a pop and they appear to out perform the MSD version coil packs. so despite the problem i may end up with a performance upgrade fixing it.

 

Here's a better price, and I'll bet it not the cheapest you'll find if you look around:
http://store.summitracing.com/partde...5&autoview=sku

 

thanks for the link, now i know where to get them from.