fordmancometh

Hello all!
I am looking for advice for my '02 F150.
My friend and I have been working on it for several weeks. This is what we have done so far.
Replaced:
Mass Airflow sensor.
Pre cat 02 sensors
Fuel filter
Air filter.
Getting ready to replace plugs and wires.
Got egr code we haven't addrressed yet but we are eliminating each as we go.
No apparent vacuum leaks.
Very rough idle, especially when cold.
Help!

DarrinT04

i think you have replaced more parts than necessary. go ahead and replace plugs and wires and see what that does

fordmancometh

I have replaced what was coded. After replacement each code has not reappeared.
I failed to mention, the truck had 202k miles on it 1 year ago when I got it. It now has 239k miles.
It's an every day driver and runs fine when I accelerate.

fordmancometh

The truck ran fine up until a few weeks ago.
The rough idle reared its ugly head again.
Codes show general misfire and a few other things related to O2 sensors.
I replaced the O2 sensors this time last year.
I am going to pull the plugs to see what kind of carbon buildup has caked on as I fear this is what could be the misfire problem.
I replaced the upper intake manifold gasket and the grommets that went with it this time last year.
Anything else that anyone can think of?

Thanks.

FaceDeAce

First off, you did not say what engine this is we are working on. Some of the advice may not be applicable.
If it is a 5.4 ... Yes, I have an idea. Stop throwing part at it! Forget all that other stuff you have gone after replacing or planning to. Instead, start with the intake assembly. Your problem is described as rough idle. So go after the specific things that control idle. Example: the idle air control valve. It is at the back of the throttle body assembly. Take it off and clean it. Replace it if necessary. Actually, just take the whole throttle body assembly off and go through it. Comes off in one piece with idle air control, EGR, and throttle body attached. Get that out onto the work bench. Take it all apart, all pieces off. Give each component a thorough cleaning. Clean: idle air control, throttle body, EGR, then attack the vacuum ports and PCV ports on that assembly. Put back in and hear it purr.


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