Ford 4.6, No Codes, Slight Driveability Issue

[dogememe]

Since buying this car, approx 166K miles, I had the following problems and resolved them as follows:
-P1233 code: Replaced FPDM, didn't fix it, so I did an electrical test and repaired a broken wire and that fixed that problem.
-P0152 code: Replaced B2S1 o2 sensor with Bosch direct-fit (not universal junk) sensor and that fixed that problem.
-Replaced MAF sensor... compared to the two Crown Vics I've had before, the car just didn't seem to be running right, and it shifted "weird" - I also cleaned the throttle body while I was in there (it was pretty clean, I don't think I'm the first person to clean it lol). Anyway the car is sooo much better after changing the MAF sensor and all that. I cleared the codes, it set the emissions monitors just fine, and it passed the smog so I could register it, great!

Only thing is... something is still wrong. Do I have to fix it? No, the car runs and drives OK, but I'm picky and I want it to be perfect. Fuel trims are good, no codes are set. I have maintenance history for almost everything from 0-150K and then it was privately owned for about 15K miles and I have no maintenance records in that time. I did some digging into the seller's Facebook profile after I bought it (oops) and the reason he sold me the car is he thought the transmission was going out (due to the bad MAF sensor lol). Anyway, I don't see anything for spark plugs, maybe they're original - would that cause this issue? Btw, I know they are a bit of a pain to change and likely to blow out of the cylidner head if not torqued properly - which is why I haven't changed them.

On to my issue, is that it just doesn't feel like the engine is running like it shuld. My 99 civilian Vic and my 07 P71 which was basically identical to this one both idled a little smoother. I wouldn't go as far to say as it's a rough idle it's just not completely smooth. And it runs fine and has plenty of power, I just feel that it isn't quite as responsive or peppy as the 07 was.

Where do I go from here?

 

[Trav]

Tune up history, plugs, filters, etc? With 166K on it the injectors may need cleaning.

 

[MNgopher]

How are the plugs and coils?

My last 5.4 and my current 4.6 can have hundreds of misfires before they will ever set any codes. Using Torque and a bluetooth OBD reader, I've been able to track down the offending cylinder and replace the offending coil (assuming the plugs are good, which is not a given).

 

[03cvpi]

I would throw plugs at it. And check all the coil wells for any moisture. May sure the coil boots are in good shape. Use a little dielectric grease and then see how it runs. You may also want to change the PCV valve.

 

[panthermike]

Trying to track down a misfire is a good idea. These 4.6/5.4's are notorious for them. I had the same issue on my '08 Vic which my brother now owns. It was a misfire, new plug and coil and it was good to go. Of course, plugs first as the coils are pricey!

As MNgopher mentioned, a good OBDII app and a cheap reader can help you track it down easily.

 

[dogememe]

Thank you all, I will dig up my OBDLink MX and see what's up

If I have a single cylinder misfire I'll throw a coil at it. Last time I checked the generic chinese ones were about $10 through my work. If I have multiple cylinder misfires I'll pull a plug and check condition.

 

[Oily_Thing]

I would put a new set of plugs in it. At 150,000 miles, the originals are probably worn pretty bad. While you are doing the plugs, do a compression test and see how healthy the cylinders are.

 

[javacontour]

Check basics like the condition of the ground, especially from engine to body and from body to battery.

What is the alternator output? Make sure you have good clean grounds and proper voltages to start with.

Intake manifold leaks? Isn't the 4.6L known for coolant leaks from the intake manifold causing misfire issues? Maybe it's early in the process and the misfire is pretty minor at this time.

If you change the plugs, you should notice if you see any coolant.

 

[Rand]

This has COP ignition?

Start with plugs, if coils are inexpensive might want to replace those.
or you can check for misfires and move the coils to see if it follows.

I dont think I'd replace them all at $33 for motorcraft parts, but some of the others are closer to 10$, no idea the quality.

maybe some lugnut put in copper plugs or they have 100k on them.. IIRC on these plugs are pretty easy to replace with decent access.

 

[spk2000]

Use Motorcraft plugs. Many people say Autolite are same plug and I tried them. Wore out in about 60,000 miles to the point car was misfiring badly driving on highway and idle.

 

[dogememe]

Alright, I'll throw a set of plugs on it. In the mean time, any idea how I see which cylinder is misfiring?

 

[Colt45ws]

You need to go into Mode 6 and that will show you per-cylinder counts. I dont have my laptop on hand with Forscan to tell you where that is. I think its in the next button down on the left side of the program.

 

[dogememe]

Originally Posted by Colt45ws
You need to go into Mode 6 and that will show you per-cylinder counts. I dont have my laptop on hand with Forscan to tell you where that is. I think its in the next button down on the left side of the program.

Thank you, I'll try it on my lunch break

 

[dogememe]

Misfires were on two cylinders, 1 and 6. I installed two new coils (only $15 each) and it didn't help. Now I have two spare coils to keep in the car - probably not a bass thing. I have purchased new spark plugs and will install them when I have time. I know Motorcraft is the best but I'm going to try NGKs because they were cheaper. It might take me a few weeks but I'll report back on what happens. Thanks as always

 

[dogememe]

Well... The gap should be 54 and it's over 70... No wonder I'm having problems!

 

[Colt45ws]

Interesting that those are 22 heat range ultrafine wire plugs, pretty sure stock is 32 standard platinium, so somebody changed them for a more "performance" option at some point.
1 step colder wouldnt hurt anything where you're at anyway.

 

[dogememe]

Originally Posted by Colt45ws
Interesting that those are 22 heat range ultrafine wire plugs, pretty sure stock is 32 standard platinium, so somebody changed them for a more "performance" option at some point.
1 step colder wouldnt hurt anything where you're at anyway.

I put in ngk 3403, is that ok?

 

[Colt45ws]

If they are listed for it then they will be just fine.

 

[panthermike]

Originally Posted by dogememe
Originally Posted by Colt45ws
Interesting that those are 22 heat range ultrafine wire plugs, pretty sure stock is 32 standard platinium, so somebody changed them for a more "performance" option at some point.
1 step colder wouldnt hurt anything where you're at anyway.

I put in ngk 3403, is that ok?


Did it solve the misfire?

 

[dogememe]

Originally Posted by panthermike
Originally Posted by dogememe
Originally Posted by Colt45ws
Interesting that those are 22 heat range ultrafine wire plugs, pretty sure stock is 32 standard platinium, so somebody changed them for a more "performance" option at some point.
1 step colder wouldnt hurt anything where you're at anyway.

I put in ngk 3403, is that ok?


Did it solve the misfire?

Yes and no. The car runs better. Idles smoother, feels more responsive, more power. Now, cylinder 1 still has a few misfires, but a lot less than before, and no other cylinders have misfires.