Yago

1999 F150
122K miles
5.8L engine V8 Engine code L
4x4 extended bed.
Please help me if you are experienced enough to tackle this.
My 1999 f150 skips at idle. You really cannot tell when you are on the highway but when you get to a stop light you can feel it miss a bit as it idles. If you go out and open the hood you can also feel it. It is as if it has the shakes albeit a little.
I have done the following.
Replaced all spark plugs from bosh to Motorcraft.
Replaced all injectors at once
Replaced all coil packs at one.
Replace EGR valve
Replaced fuel filter.
Replaced IAC
I am at my witts end. Someone please help.
There is no engine code.

FX4_GUY

On my old ford it turned out to be the O2 sensor and it never showed a code.. But this is just a guess..Also could be a fuel filter...

Nick Martini

Try checking for a vacume leak!

ktmboyz

unplug the green vacuum line at the top of the egr valve and see if it changes anything! Do you have or have access to a fuel pressure gauge ?

Yago

Yes I have a fuel gauge and the pressure is up to spec.
I have also checked for vaccum leaks and nothing.
You see the skip I am talking about is so minor that most people do not even know it when they are in the car but I do. Sometime I have to tell people to wait for it and then they feel it too. Also if you go to the engine compartment, you will feel it more. Very little but enough to be a mental torture.

Nick Martini

All I can say now is check the timing, timing belt and pullys, double check the vacume and check for codes again. Lets just hope its not inside the engine.

Nick Martini

Those vacumes are tricky to spot so get a good light and open her up and make sure. On top of that, when you check for codes you have to do it by the book and you cant cut any corners. Check the instructions that came with it and run it again. I missed a few myself.

Nick Martini

If you still have the issue get me some more info like when and where under the hood does it occur and how often.... every 5 or 10 seconds? Get under there real good and try to find its source. Sounds like it could still be a vacume or even the timing/pullys. check the pullys for wabbles or anything that doesnt look right. Just remeber that it is most likely to be something moving...........good luck and let me know the outcome!

Yago

Thanks Martini,
I used Autoengenuity code reader and this are the codes I got
B1352 Iginition key in circuit failure
B1869 Air bag warinning indicator lamp open.

This was also in the red (out of spec)
(Catalyst monitoring Bank 1 switch )

Evaporative system Monitoring
(Initial tank vacuum and min and max limit)

Evaporative system monitoring
(Vapor Generation max pressure rise)

NGM

None of those dealer codes you found will cause a miss. If its so light that no one else would notice, I would guess its the engine showing its age. How did you check for vacuum leaks? If it were mine I would do a BG induction service on it. Drive it for 1000 miles and do it again. See if its carbon buildup on the valves.