it's doing it again....

[robmedina]

OK, so far, I changed the fuel filter, cleaned the MAF & IAC, new air filter, replaced one vacuum hose. I am planning on having the plugs and wires changed next week.
What it's doing:
random sputter when idling. runs perfect otherwise, any suggestions?

 

[robmedina]

I have been reading posts that sound similar to my problem as well as the tech library and can't seem to find a reason.
I think I may have another vacuum hose/ vacuum problem somewhere, I looked everywhere , not really sure where all the vacuum hoses are. I think I will try the carb cleaner method today.

 

[LearjetMinako]

It definitly sounds like a vacuum leak somewhere. Heres a start, pull the vacuum hose tree off and plug it with your finger. If the engine idles better than it is somewhere in that tree's lines. And don't forget to check the brake booster, fuel regulator, and PVC line too.

 

[robmedina]

It definitly sounds like a vacuum leak somewhere. Heres a start, pull the vacuum hose tree off and plug it with your finger. If the engine idles better than it is somewhere in that tree's lines. And don't forget to check the brake booster, fuel regulator, and PVC line too.

Forgive my ignorance, but do you have a picture of any of this stuff? I noticed a black box near the radiator that has 2 lines coming out of it. I replaced the one really bad line today (it was a larger diameter on one end and tapered down )What is this thing?
I went to autozone and the code is P0171 which is FUEL BANK ONE CONDITION, the computer has recognized a rich or lean condition on one engine bank only. Possible causes: Fuel Pressure or MAF sesor, Oxygen Sensor defective, Ignition misfire-repair or Fuel Injector problem.

 

[robmedina]

I just ordered Motorcraft plugs and wires - the 439's. hope it helps.

 

[snake]

So far the majority of p0171 codes I have dealt with have been a hole in the PCV line, usually sucked open by vacuum... but any vacuum leak will do it. Check the flexible hose between the air filter and intake as well, as unmetered air will cause this code and a crappy idle.

 

[adsm08]

Do the carb cleaner test. Intake gaskets are a pretty common cause too.

 

[TheTopher]

Does your truck have AC? My AC has a leak and right about this time of year the engine gets a little funny from the AC compressor turning on and off and causing the RPMs to sputter a little. This obviously doesn't happen while I'm driving since the engine is locked to the transmission, only when I'm at idle. For some reason our generation of trucks thinks the compressor needs to be on at almost every fan setting. Don't ask me who thought up that one.

I just discharge it this time of year and just recharge it in the summer.



As a test, the next time it starts doing it, turn your fan off and see if it stops.


Edit: Whoops, I hadn't noticed the code post.

Carry on!

 

[o-zone]

As a retired wrench turner I would go straght to the upper intake or the lower intake with carb cleaner and I bet you find the miss your looking for.

 

[Rangerboy]

Hidden little hose under the throttle body is probably dry rotted! Check here first.

 

[r1hatman]

As a retired wrench turner I would go straght to the upper intake or the lower intake with carb cleaner and I bet you find the miss your looking for.

^X's 2! Vacuum or intake related more than likely.

 

[r1hatman]

As a retired wrench turner I would go straght to the upper intake or the lower intake with carb cleaner and I bet you find the miss your looking for.

^X's 2! Vacuum or intake related more than likely.

Have you tried Sea Foam? That crap is the bomb! Really helped mine after it had all that blow in the carb!