Hey everyone,

I've been scouring the forums about this rough idle and stall issue that people seem to be having but so far haven't seen any comment about operating temperature where this starts to occur. Maybe I've missed it along way but here's the symptoms I'm having:

1. Truck starts fine and RPMs stick around 800 while it's warming up
2. After a few minutes at idle the fan starts up and it surges up and down
3. The RPMs then fall down to 5-600 and it idles very rough. Sometimes it will sit nicely and idle for a long time but eventually it does stall

When I'm driving and the engine is at full operating temperature this rough idle is so noticeable that at a red light I'm having to put it in N to keep the revs up or it'll just bog down and stall.

I've read about vacuum leaks and the shop that I had it in recently suggested it was a vacuum leak 'somewhere' and they wanted to run a smoke test to track it down.

I'm a weekend mechanic and do most of the work on my vehicles so paying them to chase down phantom vacuum leaks is the last thing I want to do.

I've cleaned the MAF - didn't solve the problem. I was going to clean the TB next and replace the gasket next. Not sure if that's really the problem though so again it's me chasing down a problem and spending $$ to come up empty handed.

The key thing here is that it starts to idle rough and stall once the truck is warm. So with that being said.. what suggestions do you gentlemen have for me?

Many thanks in advance!
Ty

 

Posted a video of the truck running..

Truck idles when first started then once it warms up it idles rough and then stalls. In this video you can hear it surge and struggle to maintain RPMs. The video ends because I stopped it thinking the truck was going to just run fine but it up and stopped immediately after I stopped the video. Just.. died. It restarted fine after but idle was rough as usual.

Just a note that when I reach my hand into the engine bay is when the truck starts to idle really poorly. It had nothing to do with my hand and where it was. It just happened 'at that time'.. lol

This is pretty troublesome when I'm driving as it surges when I come to a red light and I have to keep the revs up or put it in neutral. Vacuum leak perhaps.. but where do I start looking for it?

This first started happening one night when I had stopped for gas. Then when restarting the truck I flubbed in turning the key and the truck didn't turn over completely and stalled out. It happens some times right? Anyways.. immediately there was smoke coming from under the hood. It was a mix of blue and white smoke. Pretty baffling and I had trouble getting the truck started again.

It's run like crap ever since with this terrible surging and stalling. Nobody seems to know what could have happened. It ran perfectly fine before that event.

So I'm looking for anyone who's experienced this.. or has some idea as to what could have 'blown' to cause the smoke coming from under the hood.. I have no idea at all.

I really could use some help here guys.. if it's just something simple like a vacuum leak.. then where did the smoke come from?

Anyways.. here's a link to the youtube video I just posted. Truck seems to run fine then surges and idles rough. Then it stalled out right after I shut the video off.

 

Need to check the iac motor (idle air control).. You can remove it at clean it, if it's real nasty when you remove it, I would just replace it.. Should be able to get one for about $50.00

 

Clean the throttle body

 

The iac is different from the throttle body

 

Sorry didn't read.. Thought it was op saying he cleaned it ...

 

04's don't have IAC, they have an electronic throttle.

 

didn't realize that.. thanks.. sorry to mislead op...

 

I just looked up the truck here at work on Mitchell ondemand our labor/ parts guide... it does show to have a iac... I looked up a 2004 5.4..... i am not attempting to be argumentative just trying to help op... i have noticed arguments seem to break out pretty quick around here....

BWD part # BWD 31019

 

That is probably on the 2004 Heritage which was the old body style. The new body style with a 3v does not have an IAC, it's electronic as stated above. Causes lots of confusion at parts stores etc.

 

I agree with Bluejay, but what you may need to do is look it up by VIN - the "old" 5.4 2 valve is VIN "L" and the "new" 5.4 3 valve is VIN "5". Rock Auto also lists an IAC for the 2004 F-150.

 

Hey guys.. it's a 3V. So based on what I'm hearing.. it shouldn't have an IAC?

I did clean the MAF and was going to clean the throttle body today but it's a bit too cold outside and freezing my nuts off isn't appealing.

I had thought maybe I was having an injector problem or some coils were dead.

I had the problem with the smoke on start up again last night.. well.. it wasn't smoke.. but the smell of burnt oil when I didn't turn the truck over all the way. I have slippery fingers I guess haha.. anyways.. the truck didn't want to start but eventually did turn over.

The idle is still pretty bad. So .. first thing is to clean the throttle body and then will report back.

 

Have you gotten a check engine light yet? If so what is the code? You can also have it scanned for pending codes, that would help a lot.

Just for S & G check the entire PCV system, that is just a guess. But a bad or sticky PCV valve could make it do that. Also check the hoses for cracks or softness.

 

Check fuel pressure.

 

Would need a scanner to check fuel pressure.

You might want to check the FPDM for corrosion.