F150 missing only during warm weather

My '99 4.6L F150 was/is missing under load and it was suggested here that the plugs & wires should be replaced. Well, I replaced the PVC valve and the problem stopped, but it also got cold out. Two days later the weather warmed and the missing came back, the weather turned cold again and the truck stopped missing. I haven't replaced the plugs and wires yet because I had to do a brake job and couldn't afford both. Considering the cost of new plugs & wires, I want to be reasonably sure that new plugs & wires will stop the missing. Would cool/cold weather (40 degrees or colder) stop a truck missing if it were because of bad wires/plugs?

Reply to
McQualude
Loading thread data ...

On Fri, 02 Jan 2004 06:04:52 +0000, McQualude rearranged some electrons to form:

I doubt it. It could be humidity-related.

Have any trouble codes been set?

Reply to
David M

As i said earlier, replace the wires.

Reply to
johnny

On Sat, 03 Jan 2004 02:33:46 +0000, johnny rearranged some electrons to form:

Yeah, you may have something there.

Reply to
David M

Sorry, I don't understand this part... cold air holds less moisture, so the air is drier, so you believe what? The cold air is forcing moisture into the wires? It doesn't make sense to me.

Wires & plugs alone are going to cost ~$150, maybe chicken feed to you, but not to me and especially not right after doing the brakes and then Christmas.

Reply to
McQualude

It's $76 to put it on a machine to be tested, which is half as much as buying new plugs and wires. I'm trying to get a consensus on the problem before throwing money at it.

Reply to
McQualude

On Sat, 03 Jan 2004 04:55:52 +0000, McQualude rearranged some electrons to form:

Right idea, wrong reason...

I think what johnny meant to say was that warm weather and in increase in humidity could encourge cross-firing between wires. Personally, I don't think that's your problem.

PS: Autozone used to read codes for free... I don't know if they still do or not.

Reply to
David M

Well, on my 1990 BroncoII I was having a problem with the engine. After a bit of go-around and incorrect diagnosics, it turned out that the plug wires needed to be replaced. During the last few really warm days (about a month ago) the engine was barely usable it had so little power and was shaking a lot. When the weather turned cold it started running a lot better. The final test was a tech told me the diagnostic scanner reported some "skips". He threw water on the wires and the engine started bucking like I reported. With new wires (it already had new plugs) the engine ran much smoother.

You might want to try spraying a mist of water on the wires and see if that causes any reaction.

-D

Reply to
Derrick 'dman' Hudson

Ok, thanks. I was looking for some confirmation. I'll change the plugs & wires and hope that fixes it.

Reply to
McQualude

Pull the plugs after -carefully- removing the plug wires and replace them. We recently replaced the OEM plugs on our '98 F150 STX after approx 75K miles and the plugs were SHOT. I really don't know how the truck still ran! Autolite Platinums will run ya under $20 and pick up some di-electric grease while you're at the parts house, as well as some never-seez for the plug threads...

Randy a couple late-model Broncos and 98 Fseries

Reply to
rokkinhorse

LOL. I wish. Cheap wires are $60/set and cheap plugs are $2 true, but OEM wires are $150/set and OEM plugs are $10 each. Estimated time for an experienced mechanic is 3.5-4 hours, for me it would probably be 8 hours. The time estimate isn't bullshit either. Damned if I'm going to spend 6-8 hours putting in cheap parts that will have to be replaced in 1/4 of the time as OEM.

Reply to
McQualude

Preach it brother! Never could understand why someone would buy cheap parts and then attempt to justify it by saying there is a lifetime guarantee if there is a problem. The work is too hard to do, and to have to do it two or three times just doesn't make sense.

Reply to
D F Bonnett

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.