Hello All,

I am experiencing a rough idle in my F150 4.6 2002. This first started after about 9k miles

Rough in this case means you can feel vibrations in the seat and console etc very annoying. This is not intermittent but is less sometimes and worse others but always detectable.

After several trips to the dealer with, No problem found on the service report , I finally spoke witht he mechanic who troubleshot the problem. In his words 4.6 engines have a known rough idleing condition nothing can be done about it.

This seemed to develop after several months

Anyone hear or experience this

As always Thanks for the help

John

 

Does it feel like the engine is misfiring or does it just feel rough? Can you feel the vibration if you put your hand on the engine while it's idling or do you only feel it in the truck?

 

Hi Racerguy,

Thanks for the repy

Not like missfire but certainly feel the vibrationb through exterior body as well as interior. In fact the mechanic poped the hood and felt where the decals are fro the belt etc You could feel it there.

John

 

My 2001 with the 5.4L does this too and I too have been told that this is normal. It almost acts like a lean condition, it has a flutter in it that can be felt in the truck.
It runs fine other than that. I am assuming that it is set up to run lean for emmisions reasons. My 5.0 Mustang has also done this since it was new. The dealer tried to tell me it was because of the big HO camshaft. It still does it @ 156,000 miles and hasn't hurt a thing.
Jimmy

 

Hi Jimmy,

Thanks for the reply. You and racerguy are the best. You guys really take an interest. Thanks.

I would agree that it is probably not a issue of longterm damage However it is real annoying especially if sitting in traffic to feel this nicely appointed FX4 XLT shake under your seat . The real gotcha is that it did not exhibit this until about 9k miles I have a 93 Taurus with 180k on it that idles smother.

The mechanic told me that it is a lean condition with the shortterm fuel numbers being -1 to 1 with zero being the target The long term number was 5

I cant believe they cant smooth it out. i wonder if upping the octane would help

John

 

I doubt that changing the octane would do anything for it but it wouldnt hurt to try.
Have you checked anything underneath the truck at all? Could be something simple like a bent exhaust hanger causing the exhaust pipe to hit somethere or something like that.

 

Dave:

This is very surely a engine vibration and from Jimmy's post looks like a confirmed kill that the idle in Ford trucks is not very smooth and that Ford has recognized this. So the question is why no fix. Since Jimmy's is a 2001 and I have a friend with a 03 exhibiting the same condition. I will try to get some meaningful answers from Ford (Yea Right)and will post here if I do.

John

 

Keep me posted, I've had mine back to the dealer twice and got the same answer. This is normal for the 5.4L. We have two 2000 F250SD's here at work and they idle smooth.
Jimmy

 

I just stumbled across something interesting.

TSB 01-24-8 says...........


ISSUE:
Some vehicles equipped with (Seat Integrated Restraint) "SIR" seats may exhibit a seat vibration or shake while at idle in gear. This may be caused by a combination of engine idle speed, motor mount material and the need to neutralize the Powertrain system.

ACTION:
Verify the condition. Reprogram the Powertrain Control Module (PCM) to raise the base idle speed, replace engine mounts (vehicles produced 11/1/00 through 5/1/01 only) with a softer design mount and perform the Powertrain Neutralize Procedure to help reduce the amount of energy transferred from the engine block to the seats.

SERVICE PROCEDURE
Reprogram the PCM with a new calibration to increase base idle speed. Refer to the following PCM Information Chart.

On vehicles built 11/1/00 through 5/1/01 only, also replace Engine Mounts. Install the following engine mount service parts (Left Hand XL7Z-6038-CA, Right Hand XL7Z-6038-AA). Follow the procedure in the 2001 Work Shop Manual, Section 303-01


it then goes on to give details on the procedure.

 

I have noticed this in my truck too. However, these are trucks, and some vibrations will go noticed. I can see boths sides of this. Just because ford will say something exists, doesn't mean its wrong. it could be a harmonic of the engine at a certain idle rpm (as suggested by the TSB). Kinda like, why do I hear wind noise on the highway. Well, because you are going 70 mph. Sure it might be nice to get rid of it, Ford might recognize its there, but doesn't mean anything can be done about it that wouldn't involve "redesigning the wheel".

 

Thanks for the replies

Dave: I will check it out thanks for the research it's much appreciated.

Aldridgec: Thanks for the reply I think the one thing that's gone un-noticed in these threads is that this condition did not start till about 9k This truck was wicked smooth before that. This is the 7th ford pickup I have owned and none to my knowledge have been like this.

 

 

Hi Phil,

Thanks for the reply:
Yes it is very much like that in the 1998 except it smooths out quicker. I have sent Ford the info this AM.

Stay Tuned This is getting interesting

john

 

Well, changing the idle will not help. I can feel it up to at least 2000 rpm when not in gear. It still has the slight miss/vibration even if I slowly rev the engine unloaded up to at least 2000 rpm. It is either tuned extremely lean or something is trying to wait another 6,000 miles to mess up after the warranty is gone.
Jimmy

 

I wonder if the camshaft might have gotten damaged during the break in period? You need special greese when installing the camshaft, and when you first start the engine for the first time you can not let it idle. The cam needs to do a quick break in and oil lube when you first start it. Some say to keep 2000rpms for 2-5 minutes and that breaks in the push rods and cam. They also say if you let it idle during the break in time that some camshafts will go flat (bad). Older chevys camshafts were made with cheap metal and was famous for people ruinin camshafts on new engines. haha