01 F150 P0304 and p0307 codes Did the typical stuff already

Ok, 01 F150 5.4, 66,000 miles Truck is running like absolute garbage.. It started running bad this pass weekend on a 5 1/2 hour trip. Burned a ton more fuel, only got like 6 miles per gallon towing the trailer.

Misfire code cylinder #4 and cylinder #7. After doing the normal plugs, boots, etc. I am still having this problem. I have changed the coils and plugs, swapped injectors, injector cleaning at shop, no luck. What else can I try?

We verified the coils are working on those 2 cylinders with a inline spark tester and tested the injectors for those cylinders with noid lights and still no luck. Swapped injectors with different cylinders and still no luck. Did compression test, 120 psi. I hate to throw more money at the truck but I am at wits end with this problem.

I am going to check for intake and vacuum leaks along with checking the cat.

fords will sometimes flag the wrong cylinders on misfires. usually a coil will fix fords misfire. spark tester to me just verifies that the the circuit is good. dont rely on this to say the coil is ok. #4 cylinder back right corner..#7 cylinder next to last on left side correct?

Correct #4 is passenger rear and #7 is 2nd to rear on drivers side.

I talked to another tech last night and he seemed to think it is either a vacuum leak or manifold leak. He kind of ruled out computer problems due to me doing all the usual stuff and swapping parts from cylinder to cylinder.

He also told me to look at the air control reading (wrong termanology, having a brain fart) on the scanner to see if the motor is compansating for an air leak and de-fueling the motor causing a lean condition.

I will have some time tonight to look into things more.

never seen a vac leak form the intake gaskets on a triton motor.. the pcv hose will get mushy and split this fits onto the rear of the throttle body adapter but this will usually cause a 171/174. you can look at fuel trim numbers and see if the short term % is positive this would indicate a vac leak, but if the numbers are around 5% plus/minus then that is not your problem. so you did change the coils already?

I know lots of techs that will not change just the boots, it's complete coils on all of the cylinders all of the time!

Yes I put new coils and plugs in #4 and #7. no change

what i would do and you may have already done is unplug the coil on #4 and #7 one at a time and start the engine and make sure that those are the cylinders that are actually causing the problem. i have seen ford's flag the wrong cylinder on misfires. we have a ford ids scan tool so it have a power balance feature for misfires makes it a whole lot easier.

I will try that. I have tried it when I swapped the injector and the coil to another cylinder and the rpm dropped but I have not tried it on 4 and 7.

I just assumed they were working due to having the noid light on the injector and inline spark tester on both the cylinders. I have not checked the other cylinders with the inline spark tester. I have probably reset the codes 10-15 times since the problem started and it always throws the code for the same 2 cylinders. The codes show up as soon as I start the truck back up after clearing them.

I will have time to work on it tonight.

Thanks for the help.

do the plugs keep getting foulled in those cylinders? If you want to verify that you are on the correct coils then unplug the injector on the same cylinder. you'll generate an injector fault for that cylinder and confirm that you're on the correct one! I've seen alot of techs get buggered up on fords cylinder layout so consult a manual if you have one!

Had some time to work on the truck last night and still no luck. Here is what I checked last night.

Pulled the wires off cylinder #4 coil when running, no change in rpm
Pulled the wires off injector #4 when running, no change

Sprayed silicone spray (safer than ether or brake cleaner, propelent is propane) over all vacuum lines and intake, no change in rpm

Had a friend bring over his snap on solaris scanner and run some tests. Found no intake manifold leaks.

Also this is the wierd one, his codes came up different than mine. My hand held came up with the misfire codes in 4 and 7, his all the codes (like 10 of them) all had to do with the maf sensor and bar sensor. My brother has a 99 f150 and I am going to see if the maf sensor is the same and swap them out.

Also noticed some other questionable things. We never drove the truck but had it idling for about 15 minutes at a time and noticed that the egr tube never got hot, you could grab and hold on to it the entire time and now the exhaust is getting that rotten egg cat like smell which would make you think the cats are plugged. Also you could hold your hand over the exhaust pipe and it would not create any pressure but that may be because I have now noticed an exhaust manifold leak since all these problems started.

Now the truck has only 66 k on it and it only really gets used as a tow vehicle. Guess I am going to have to dig in a little deeper and see what I find on the egr and cats.

sorry for the long drawn out reply but I am having no luck. Maybe like have to bow in defeat and take it to the dealer. I am not going to like that bill....

Thanks,

Matt

I did check the plugs back when this first happened and they were ok but haven't checked them resently. I got the manaul for the truck which is both a help and hinderance.

Well with the skip being on opposite banks and this having a convertor 1 per bank I wouldn't think that both of them are stopped up. What were all the code numbers. You have to remember no exhaust if flowing through that pipe at idle only when the valve is open.

Still having the problem and still getting the same codes but found something interesting last night.

I was driving around with the scanner last night looking at the graphs and noticed that when the truck went into open loop (roughly 3000 rpm on highway with od off) that the misfire would stop (according to the graphs) and when I dropped the rpm and the truck went back into closed loop that the computer would detech a misfire. take the truck back up in rpm to open loop misfire wouldn't detech a misfire.

What I am thinking is that one of the sensors is telling the truck to run lean in closed loop or it is rpm related. The maf sensor voltage is in the range it should be, fuel pressure checked out ok 32 psi at idle, more when vacuum disconnected. I am baffled.

I still want to swap MAF sensors with my brothers truck to double check that. Other than that, I am going to have another Tech look at it tomorrow night or Friday.

Just my .02, but Ford trucks have alot of MAF problems. In 2007 my 1998 Ranger 2.5 started running like crap and eventually got to where it wouldn't start. It never threw any codes. I put the scan tool on it with the key on and noticed the MAF value was showing airflow going through the sensor as if the truck was running, which it was not. I unplugged the sensor, causing the truck to go to open loop and it started right up and ran well enough to drive. I replaced the sensor and it has run good ever since. The guy at Carquest said "yeah, we sell alot of those" when I told him which one I needed.