I have a 99 f-150 crew cab with 105k on it I recenty (in the last 250 miles) replaced the cops with moto blues, the plugs and the upstream o2 sensors. It runs great except when the engine is cold it has what feels like an intermitant miss. It goes away after the engine is warm. Its been cold here in the last 2 days for the first time since I've owned this truck getting into the 30's the last couple of days. I'm wondering what could cause this. The C.E. L. does not come on. Winter is coming and I dont want my truck to run like crap when its cold. Any ideas? iIt didnt do it until the last 2 days when it got cold..

 

If weather was ever a factor in my truck running goofy, I would pinpoint to the IAC and either clean it or replace it. While doing that, clean the throttle body out good, both sides and the ellbow that heads into the intake. See if that helps. Unplug the battery make sure (good to do anyways) but if you don't the IAC may act funny after cleaning like idle funny or be noisey. It should go away fairly quick if it happens.

 

I looked up the symptoms of IAC failure and it really doesnt match my problem. I replaced the fuel filter yesterday and I'm gonna try starting it and see if that cleared it up. if it didn't I'll put cleaning the throttle body and IAC on my list. Probably should do that anyway.

 

Blue20004x4 knows his chit. I reccommend taking his advice. You will soon find that the symptoms in a book in regards to the issues you are having are a 50/50 shot. Pulling the IAC and cleaning it is a 30 minute job tops. Becareful not to tear the gasket when you pull it off. As the IAC plays a big role in the idle of the vehicle it is something to be checked off a list. That being said, some people have had issues with the MotoBlue COPs but your problem doesn't seem to be consitant throuhg the operating cycle, only on start up when the engine is cold. If the IAC is gunked up then a stutter could take place at idle do to its inability to open and close smoothly. As the engine warms the gunk may take on more of a lubricating effect....just clean the bastard and be done with it.
BTW, what engine do you have?

 

I have the 5.4 I started it this morning and its still there. I thought about the Motoblues wondering if there crap. I probably should have went with the motorcraft ones. Hope I dont end up having to replace them. I'm also wondering if it could be an injecor failing. I'll try cleaning the IAC first.

 

Well I cleaned the throttle body and went ahead and replaced the IAC. I'll have to wait until morning to get a real good feeling for it but right now it still does not seem to be running as smooth as it should be. I'm really starting to wonder about those Motoblue cop's. Wish I had gone with the motorcraft. I may have to replace them.

 

Thanks man (a tear falls down my cheek) kidding!!!! All that aside jethat, does it run better, just something is still a miss? If it's what I'm thinking, just a slight stutter maybe? That is as far as I can tell pretty normal and it does seem to go away when warm. But doing all you did is not to go unrewarded, as it's good maintenance most people neglect. It's too hands on for yuppie's. I've found that failing coils are not so nice, like no slight vibration, kinda the feeling you get just before you run outta gas, in this case, it's a bottomless pit of gas just runs like it's on fumes. If you have doubts, re-do the coils and add silicone dielectric grease in the boot if you hadn't done that earlier. This is more for the long term in corrosion prevention, but always a good idea. My other concern is battery. How is she? Is it old, are the posts in need of corrosion cleaning? If so, add dielectric grease to them too, liberally, and you'll be happy like I am with the results. All the best fellas, cheers!

 

It does run better it seems to have a bit more power and when I floor it it makes a roar it didn't make before. Sounds better. I replaced the battery when I bought it. The odometer was flicking out when I got it and I found a repair for that on this site in the electrical section I went to disconnect the negative post and it was so corroded I couldn't get it off broke the post on the old battery. Had to buy one of those crimp on connectors. I soldered it on and I hope that's good enough. looks like a drag to replace the negative wire. I'm sure it's dealer only deal to. I used dielectric grease on the boots so It shouldn't be that although it did rain here a couple of days ago and I recall going through a big puddle. Wondered if water got in there some how. Seems like it would have dried out by now and the truck ran fine at the time. I dunno. I'll see how it runs in the morning.

 

Ya, weird how that works. The day mine went, it had rained a ton and I went through a big puddle = way cool (or so it seems). Hours later, started it up, drove down the street for a few minutes, then it started to act all retarded. Got it home, figured it dried off cuz in idle it ran fine, revved it=fine, but next day, there she went again. Jbrew and some others were quick to pinpoint the problem and walah, fixed!!! I'd give them another look and dry out, maybe re-apply the dielectric too. How are the plugs? New(ish)?

 

Plugs are brand new. I'd rather not take them coils out again. maybe I should take it out on a nice cruise and get it really hot. See if that works. get it dry. It was a big puddle. Maybe I'll have to avoid them like that. Course if it keeps it up I'll have to do something. I used an old spark plug greased it and reamed the boots out. Cant imagine they need more. I'll see how it goes tomorrow.

 

Screwed around with it forever couldnt figure it out so I finally broke down and took it to the dealer. One of the Motoblu cops that is less than 30 days old is weak. should have got the motor craft ones..

 

Ebay has them too if I'm not mistaken, around 200 bills for the set of 8. I haven't heard anything bad of the Motorcraft coils so I tend to stick with them.

 

the Motoblues are under warantee so I'll warantee this one if it happens again I'll junk them. I regret buying them now but I was sold on there promise of a 15 hp gain thought it was worth a shot. Guess that old saying that goes if it sounds to good to be true it is..