The nasty miss is back.

[FUTURE_OF_GM]

Well...

Any ideas?

The car picked up a bad miss in February of this year and I put replacement platinum plugs in. That cured the miss for the most part (it has always had a very slight miss at 14-1500 RPM -- Apparently that is a characteristic of some of the 4.6L cars and something that a lot of people 'live with')

Round about May, the ugly miss came back. I added some fuel system cleaner thinking that it couldn't hurt and the miss went away.

This weekend, I've been moving so the car has been racking up a lot of interstate miles. Sure enough, today I was getting of the interstate and it's like someone flipped a switch. I added more fuel system cleaner (again; it can't hurt anything and I don't trust the fuel system in this car to begin with) but the miss is still there.

It seems to cut out real bad when it's pulling from 1000-1400 RPMs, then it clears up and the car runs great (about 1800 RPMs -- cruising speed on the interstate)

The car has about 124K on it now. I'm thinking about picking up some new coil on plug cap (I guess it would be called a cap) tomorrow to see if that's the problem. (Again; can't hurt) But if that doesn't fix it, I'm not sure where to go...

Should I tear into the ignition system or do you guys think my suspicions about the fuel system are warranted? The car is due a fuel filter, but I haven't been able to get home and install it (2 hours away where all of my tools are and the majority of my maintenance happens)

I've also read about some valve on the throttle body that makes these cars miss. (I have very little experience with modern cars)

[ocnblu]

Darn it, nope. I was hoping this thread was about an ex girlfriend of yours.

[Camino LS6]

I'd do the fuel filter first since injected cars are very sensitive to a clogged filter. I'd also check the air filter.

If that isn't the source, I'd try pulling plug wires one at a time to narrow down which cylinder has the issue. It should run with two misses for all but the bad one.

[loki]

if it's anything like the miss in my 3.1L i had.....try replacing (or trading) the spark wires with another car. solved my problem with coils/wires from my sisters 3.4 to my 3.1 and she's not had missing problems.

[FUTURE_OF_GM]

Well,

I replaced the coil boots and that *mostly* took care of the problem... By that I mean it runs pretty good 3/4 of the time and like straight sh*t the other quarter of the time.

The fuel filter will hopefully be installed this or next weekend and the air filter should still be good to go. I cleaned and reconditioned it last time I changed the oil (it's a K&N)

I'm really afraid that I have a coil going out in which case I'm going to have to do one of two things. 1) buy "a" coil and troubleshoot each of the cylinders (install and remove the coil) until I find the one that's dying. That way I can buy a little bit of time before I have to drop some change 2) Just man up and buy $400 worth of coils nd change them all.

Right now, most of my commute is interstate driving and the car does fine cruising on the interstate. It starts missing when it kicks into O/D and 'lugs'. As of now, when the car hits O/D and starts lugging, I switch off the overdrive which raises the RPMs into the 'cruising' range where there is no skip. When the car gets to a speed that can support O/D better, i.e. doesn't lug as bad, I switch it back on.

Kinda sucks, because I'm at a point now where I can begin to properly maintain (meaning do better maintenance and replacement than jut basic stuff) this and my Camaros (with the new job) if it'll just hang on for a few more weeks.

I had a real bad feeling this was happening back in January... I fired the car up after a damp couple of days and it had a *slight* miss. I knew at that point moisture was getting into the system somewhere but wasn't sure where or how to fix it. The coil boots were old but in good shape, so I didn't sweat it too much. Come to find out, sometimes the hood scoops leak on the #2 and #3 cylinders and cause the coils to eff up.... I'm *assuming* that is what happened to mine. But until I change the coils, and find out it could be just more dead ends.

Edited August 25, 2011 by FUTURE_OF_GM

[Camino LS6]

Hmmm.

The connection of the condition to being in overdrive has me wondering if something else is going on. I don't think it should lug in overdrive - miss or no miss.

[FUTURE_OF_GM]

Well, by 'lug' I mean just low RPMs where the motor is taxed or pulling.

When it's running normally, the O/D on this thing kind of reminds me of GMs fuel saving shift thing. The car will accelerate and then when it kicks into O/D it just murders the motor. It's like someone flips a switch. I really hate that transmission. It seems like Ford didn't have a decent auto, so they just 'threw this one in'.

[Camino LS6]

Ford was notorious for not so good autos for quite a while.

Still, it shouldn't fall on its face like that.