the dreaded PO304 code

[bigr77]

I have a 98 windstar Lx and after all the plug wires and plugs, coil pack, upper and lower intake gaskets, valve body on tranny cleaned up, this code still remains. About a week ago my car started slipping out of gear, only on left turns, now is this a vaccum issue, cause i really dont think its my tranny, ive been doin a little internet research and ive found something about my egr ports might be clogged? help me out i dont have $70 a hr to pay a mechanic to find out, especially if its a simple task that I can do.

[LeSabre97mint]

Originally Posted by bigr77

I have a 98 windstar Lx and after all the plug wires and plugs, coil pack, upper and lower intake gaskets, valve body on tranny cleaned up, this code still remains. About a week ago my car started slipping out of gear, only on left turns, now is this a vaccum issue, cause i really dont think its my tranny, ive been doin a little internet research and ive found something about my egr ports might be clogged? help me out i dont have $70 a hr to pay a mechanic to find out, especially if its a simple task that I can do.

Bigr77

Welcome to AFs!

Yes P0304 is often brought on by cloged EGR ports. If you had lower intake gaskets replaced they had the upper intake off and the EGR ports "should of" been cleaned then.

Your trannie issue may be low fluid.

Regards

Dan

[wiswind]

Dito on the transmission fluid level....top off (but don't overfill) with a Mercon V rated ATF.
With the motor warm.....on level ground.....in park, parking brake set.....engine running at idle.......check transmission fluid level.

The EGR ports 'should' have been cleaned in the mentioned repairs.
One test that you can do to see if the problem is EGR related is to locate the EGR valve.....remove and plug the vaccum line going to it.
Take the vehicle for a drive.......does the misfire still happen?.....if so....it is not the EGR system.
This test should set a low EGR flow code.....as you have disabled the EGR valve.
Reconnect the EGR valve's vaccum line.

One thing that has gotten me several times on my windstar is dirty fuel injectors.
The only cleaner that I have found that seems to work is Berryman's B-12 Chemtool.....in the metal can.
My mechanic recommended it.....and it does work.
Might take a couple of tanks, each treated with a can, to clean them up.

Hopefully you did not get talked into one of the fancy multi tab Bosch spark plugs.......the +2 or +4 .....these have been noted as not working well in the Windstar.
The match to OEM would be double platinum (both the center AND the ground tab have the platinum enancement) in the Motorcraft or Autolite brands.

[FordGuy81]

Recently my P0302 turned out to be a failed injector. After removing and cleaning it, I still got the misfire code. Replaced with a new and all is well.

I also cleaned out the EGR ports which were really built up with carbon. Use a pick tool to pick out the crud (I got a set of 4 at walmart for ~$6) and a shop vac to suck it out at the same time.

Ditto on wiswinds advice about bosch plugs. I have only had luck with Motorcraft plugs in Fords, in every Ford I have owned (5). A few years ago I had a '77 F150 with a 300 six. When I bought it, it had Bosch plugs in it. It ran OK, but I swapped in Motorcrafts and it ran MUCH better.