Hi, i'm new here and this is my first post. As the title said, I have a 98 F150 4.2L with code P0301 Clynder 1 Misfire.

This is what I have done so far. New plugs, coil pack, plug wires, TPS, EGR, EGR Vaccum control regualier, DMCP, canister, all of these parts are new and was bought from the ford place. Have taken the egr value, and egr value bracket off to see if carbon blockage was presant, but it was clean. It was clean in the motor also. Have blown air through the metel tube that conects to the egr value and it come out the tail pipe very good, so no blockage their. Have cleaned throtle body and injecters. Have tested fuel injector with tester and it works correctly. Motor holdes pressure. Have correct fuel pressure.

Do not have any vaccum leaks, it holds vaccum correctly. Crankshaft sencer is fine. Went throw 4 cans of break parts cleaner, spraying on intake while motor was running, motor did not idile up or change. I have done all this and it still shows code P0301, and it still skips. Here's the catch, if you unplug the vaccum off the egr the misfire goes away, or unplug the EGR vaccum control regulatior it goes away, or if you unplug the DMCP sencer it goes away, it does not matter witch one you unplug, the misfire goes away.

I have had several different test done the the truck, but all the test only show that one code P0301, they do not show any other codes, or problem's with my truck. Any help would be helpful. You can email me direct if you want at (Click Here to find out why email addresses are removed from posts.) thanks for your time and hope you all have a good day.

 

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the tube that runs through the intake that distributes the egr flow the the individual cylinders sometimes plug all but one hole with causes a lean missfire one that cylinder.and the only sure way that i know to properly clean it is to take the upper intake off and blow threw all the egr ports in the intake with the egr off.

 

Hello, I-m tech. Thanks for the info, but we where in the prosess of doing what you are takling about while I was posting my message. Sorry to say, but that did not help either, still have code P0301, Cylinder 1 Misfire. Been trying to fix this problem for 2 mounth's now, and my Dad has been a mech... for 32 years and it has got him dum-founded also. Any other subjustions?

 

hook up a vacume gauge to the vacume line going to the egr valve and see if it is apply the egr at idle. it could be opening up the egr at idle.

 

Hello, again I-m tech. We have done that also, and it is not opening up at idle. I also failed to mention that the misfire only happen's when it is under a load. It will not do it idleing nor reving up the motor in park. You can put it in reverse or drive and hold the brake down give it some gas and it will start to misfire then, or driving down the road. Thank's for your help on this matter.

 

Im having the same issues with my 04 4.6 did you ever figure anything out? p0301. it drives like a ape until i hit a decent uphill but flat lands its great.

 

same issues but code p0305. I have replaced the the coil pack, spark plugs, wires and injecter, and still getting check engine light. Still sputters like it is misfiring.

 

I'm in the same boat. First it was Cylinder 1 misfire. Replaced Plugs, Coil Pack and Wires. Now its Cylinder 5 misfire. All help appreciated.

 

i had some bad wires even though they were new they can still be bad change the one that is misfireing if still mis fireing change that one plug and if it is still doing that check the injecter it might be bad

 

I have a similar issue with my '98 F150 w/4.6L. However, my issue typically only occurs when there has been lots of rain (parked outside). It started a couple years ago, hard rain and when driving it missed a few times and light came on. Once the truck heated up the problem went away. I had codes read, cylinder 1 misifre, so I first replaced both coil packs. No further issue for about a year. Then after a night of hard rain then next morning the issue resurfaced, hard time getting past 45 MPH with the missing. Again, once the truck ran for a while the issue seemed to dissipate. However, I decided to replace both the wires and plugs, since they were prolly about due anyways. Since putting the new plugs and wires in last Oct ('11), the service engine light has been on and off periodically (Cylinder 1 Misfire), can notice a miss at idle occasionally, but didnt see much issue past that until recently. Again, in Michigan we are going into winter so higher humidity, more rain etc. The misfire can be noticed now more when under load and when accelerating.

Anything I should be focusing on besides plugs, wires, coil packs?? The moisture in air seems to be the driving factor so could there be a sensor or something that is being affected by it. Perhaps the plugs I put in were not a good match for the engine. I had Bosch Platinum +4s paired with Ford Racing wires installed until I changed them out last Oct with some O'Reilly supplied wires and AutoLite plugs(platinum or iridium).

I appreciate any input.

BW

 

Having the same problem - only under load. Replaced, cleaned and checked most all of the above.

Any solution to this issue?

 

Anyone check compression, or check the plugs for glazing ? Could be the notorious head gasket leak. Check coolant level, oil level, see if the exhaust smells like antifreeze.

Dave

 

I'd also put a test light on the injector for the misfiring cylinder. See if it triggers in a regular sequence ( or not at all ). the injectors might be good, and not getting the pulse to activate them.

Dave

 

The folks with the 4.6 have a good chance of having a cracked manifold! One check on the 4.6 that is some what easy drop about 1/2 the water in the cooling system then remove the Thermostat housing & thermostat look in the bottom under the thermostat if you see cracks or a rubber gasket you have found it. It leaks under the manifold and works it way back to #5 or 6.
On the first engine is miss-firing on #1 run the engine to get it missing then quickly remove #1 plug and check for moisture on the plug. While you have the plug out hold a clean cloth about 1 foot back from the plug hole have someone crank the vehicle then stop check the rag for moisture. If you have any moisture of course it is coming from somewhere. If you will check out my replies you may find a solution for your situation.