Just went to AutoZone and had them run a CE code...P0402 - Exhaust Gas Recirc Flow Excessive Detected. Ordered the part ($73) and was told to clean up the carbon in passage before installing new valve...Is this something that I can do just by wiping it, or should I use some type of cleaner to do this?

I was having rough idle when in gear AFTER replacing a cracked coil pack a few weeks back....CE light came back on today....It had been coming on intermittently prior to the coil pack problem.

Thanks for the always valuable advice....

 

Kudos to the "big wigs" at Auto Zone.

The have been selling parts to people that don't need them.

For every code they pull, they sell you a part.

I can almost guarantee the EGR valve is not defective.

To clean the EGR passage, it is best to remove the throttle body.You then take a screwdriver and scrape the carbon out of the passage. You can the spray the passages with carb cleaner.

 

Home skillet is right and wrong. Autozone always sells a part, no matter if it's right or not but that's different topic.

First what engine are we talking about? If I had to guess I would say the 4.6 as they are known for this type of problem. Second get a refund on your money as the valve hardly ever goes bad. It's either the DPFE, carbon build up, and/or both. I would do as he suggested and clean the TB. Home skillet's method is correct but you may want to use a "Coating Safe and sensor safe" Throttle body cleaner. Your TB is coated with a substance htat is suppoesed to resist sludge and build up. Carb cleaner will destroy that, second carb cleaner is bad on the sensors and cats is used while running or gets into the engine.
What you do is pull the whole TB off the truck and clean two 5/16 passage ways. If this does not work test ( can do at home with repair manaul and voltmeter) or replace the DPFE sensor ( I paid $63).

There's lots more info on here about this, just do a search.

 

I have the 5.4 engine....
your advice is appreciated...I am still confused as hell though.
I may be barking up the wrong tree....about 2 weeks ago, I had a plug come loose and crack a coil pack...2nd one back on passenger side. The mechanic replaced the coil pack and said the plug threads were fine...that was when my rough idle started. I guess that would be the first thing to tackle...I don't know if it could be a bad coil pack, or if he did not use dielectric grease (could that cause this problem?)...but considering the background I suppose that would be where to start...but could the P0402 code be explained away?

Thanks,
Mike

 

%.4 huh, not as well known for carbon problems, can still happen. It all depends on mileage, gas run, and state of tune.

I'm not sure if your two problems are related or not. Both can cause bad idle problems as well as a host of other very small things. If code 402 and your plug issues are related I would say it is due to a loose or broken vacuum lines. Maybe when the coil pack was changed out a vacuum line was broke. I would think if it where one of the EGR vacuum lines it would be a code 401 (insufficent flow) but I'm not sure.