When I start my 98 crown vic in the am starts and runs great for about a min then it starts sputtering like its misfiring recent plugs and coil packs are all sparking. it had a very little amount of snow blow over the top of the engine while the whole system was cold. engine code says mass airflow sensor and the left bank is running lean. It has been running great a lil snow got on it I dusted it off and fired it up can't get it running smooth at all now.

SOURCE: P0304=misfire in cylinder 4. coil?

not coil coil it wouldnt fire at all it is either a plug or a wire replace the wire and plugs and that will fix it

SOURCE: Ford Crown Vic p0300 random cylinder misfire

take a look at the EGR valve it could be either vacum controlled or electronic either way what seems to be the problem is that the valve is stuck in the open position until the engine warms up you can gently tap the egr valve with a small hammer or a screw driver and you can see that it runs smooth, now if the egr valve is vacum controlled replace the valve. if it is electronoc controlled replace the valve and the module for the egr valve.

SOURCE: location of O2 sensor in bank 2, 99 5.4 expedition, running lean

I have a ford 2003 windstar that was running very rough when cold and almost stalling. engine light came on. went to autozone and they read the codes for free and told me it was running lean on Bank 2 also. i came home searched for the O2 front sensors online using the info autozone gave me. there are 2 front sensors on my car that need to be replaced at the same time. look for ones that have a direct plug in and don't need wire splicing. the ones without the wiring harness are cheaper but more of a pain, i think.
they were fairly easy to replace. getting access with the wrench was the worst. reset the light by disconnecting the battery for a few minutes. seems fine now and the light hasn't come back on.

SOURCE: 1998 crown vic police. Had check engine light with

your egr on that side is dirty try cleaning it aslo check intake boltsaround those clyinders.

michael schultz

• 1068 Answers
• Posted on Oct 21, 2009

SOURCE: TOO LEAN CODES

yes very very common code for these motors i get them all the time. now the first thing i do is listen to the pcv valve for noise if it is rattling this is the problem and is the most common of all. another thing is the intakes leak from cracks in them but the only way to find it is with a smoke machine. now the one other thing i have seen before is debre like a leaf in the mass air flow sensor but you have replaced it so most likely no that.

do your self a favor and change the pcv valve it only cost under 5 dollars. if this is not it you will need to find the leak in and around the intake or a vacuum hose.

because you have two lean banks this mean if it is a leak then it has to be in common with both banks and that is the vacuum line system intake etc...

let mew know if you have any more question. good luck man