Miss under load

[Zekester]

97 Mountaineer 5.0 AWD 75,000 miles. Un-molested stock condition.

So everything was working fine until a couple months ago, when it's developed a miss when climbing hills. It's steadily gotten worse. Before it was only in highest gear, but now it's doing it in lower gears/higher RPM.

It starts fine. It accelerates fine.

Idle has always taken long to drop down after a cold start. It stays about 1300 rpm for at least 5mins, even when already warm. And now it has been a little rough driving off for a couple mins....some stumbling. But then it clears up.

I've taken a quick look and didn't see anything amiss. I've just replaced both coil packs with no improvement.

It's now throwing the P0352 side b coil code.

Battery and charge seem ok on the scanner.

I've unbolted the two connections mentioned in the sticky. They both appear fine.

Only thing I've done other than replace coils is to spray everything in the intake with carb cleaner....including the sensors.

 

[ThreeJs]

Have you looked at your idle air control valve for the idle issue? Try cleaning your MAF also.
Were the coils replaced with new replacements? Check the grounds, connections and that the ignition wire isn't grounding.
If coils are new you may want to try to exchange for another unit.

 

[Zekester]

would the IAC effect the coils? Ill look at it.

the coils were replaced with new, and after driving it today the miss seems worse.

I did clean the MAF but used carb cleaner on it.

 

[Zekester]

ok got another update after scanning again: its saying Cyl 3 misfire, and also added Ign Coil A along with yesterdays Coil B.

so i guess i’ll check out cyl 3 first

 

[CDW6212R]

How old are the tune up parts, plug wires, plugs, fuel filter etc? Cleaning the IAC is a regular to do item like the plugs, but it sounds more like an ignition miss. Don't use carb cleaner on the TB, it's too harsh for the coating on the inside of it. Look over the wiring carefully also, any damage from burned wires or breaks in the insulation, can cause misses etc.

 

[ThreeJs]

would the IAC effect the coils? Ill look at it.

the coils were replaced with new, and after driving it today the miss seems worse.

I did clean the MAF but used carb cleaner on it.

For the IAC and MAF I was referring to:
"Idle has always taken long to drop down after a cold start. It stays about 1300 rpm for at least 5mins, even when already warm. And now it has been a little rough driving off for a couple mins....some stumbling. But then it clears up."

 

[Turdle]

You need new spark plugs and wires.

Be sure to use only the suggested autolite or motorcraft spark plugs.

 

[Zekester]

thanks all.

im buying new wires now, but a little worried about changing out plugs.....dont want to bust one.

ive already sprayed the MAF with carb cleaner. is it ruined now?

 

[CDW6212R]

thanks all.

im buying new wires now, but a little worried about changing out plugs.....dont want to bust one.

ive already sprayed the MAF with carb cleaner. is it ruined now?

Not likely unless you drowned it and went in scrubbing hard. I don't know what it takes to strip the surface, but I doubt one time does any harm.

Take your time with the plugs, get a good angle and leverage to turn them squarely, they should come out readily.

 

[Zekester]

seems 5/8 is sloppy on the plug. could it be 15mm?

 

[CDW6212R]

They will be 5/8" socket sized, hopefully nobody has rounded any of them. Use a quality socket of course, cheap brands don't fit as well.

 

[Zekester]

thanks

looks like no one around here carries the wires in stock. And there are two versions for a 97.

Can i just go with the later-date wires?

 

[CDW6212R]

What manufacture date is your truck? The heads and exhaust manifolds changed mid year of 1997, which means plug wires too. The early 97 was like 1996, the 90* elbow where the TB bolts to, is flat on top, dead flat. You could set a drink on that, it's flat. The mid 97-2001 engines have a rounded elbow top, the different GT40P heads, EGR pipe on the right side etc.

The plug angles changed in the "P" heads, so the plug wire boots are different to fit better in the super tight spaces. Take lots of care when routing the wires, do them one at a time if you have to.

 

[Zekester]

the door tag says 7/96

 

[CDW6212R]

the door tag says 7/96

That means it's an early 97, with more normal GT40 heads. You need the early plug wires. I'm sure someone has used the other wires on an earlier model, but unless you know they will work, I'd get the right plug wires.

There are a few good brands, Ford is a good standard. I like the best, Magnecor, but they are almost double in cost of others. Taylor people like most of the time, but the key is insulation quality. Sometimes even the best may burn through in less than a time you'd expect, how they are routed matters a lot. You can make do with a cheaper brand, but expect those to need replacing in a couple of years, give or take.

 

[Centaurus5.0]

And use only motorcraft double platinum plugs.

Pull the cap off your Cam Position Sensor and check that for damage too while you're at it.

 

[Zekester]

oops....already bought a Bosch plug just one for now, though

that plug on the #3 cyl.....it doesnt look rounded, but it is definately smaller than 5/8. I tried the 5/8 on other plugs and it fit snug.

might have to force a 15mm on it

O'Reillys has an "OmniSpark" brand in stock

 

[Zekester]

were the P heads better?

 

[CDW6212R]

were the P heads better?

No not really. Back then they advertised better emissions and minor power, but at this age no one has reported anything worth the trouble of those unique "P" heads.

 

[CDW6212R]

oops....already bought a Bosch plug just one for now, though

that plug on the #3 cyl.....it doesnt look rounded, but it is definately smaller than 5/8. I tried the 5/8 on other plugs and it fit snug.

might have to force a 15mm on it

O'Reillys has an "OmniSpark" brand in stock

Bosch plugs are okay, they're a quality brand that I've had no troubles with. I use Motorcraft most times, but depending on prices and what tip I'm after at the time, a few brands do fine for me.