bbjack

I have a 2001 3.8 mustang (manual)

When I purchased it, then check engine light was on, the guy said he was told that it was a bad o2 sensor. The check engine light went off and I just haven't had it fixed. The mustang has had minor misfiring problems since then, and it has came on and off again. Right now it's off. But it does have a loss of power and mostly misfires if I'm going to slow for a higher gear.

I noticed that in bad rainy weather that the engine will sometimes start misfiring badly. I was on the interstate going 70 mph or so the other day and the check engine light started FLASHING. So I go to neutral and adjust gears and it goes off.

I know there's multiple things it could be. Spark plugs? Ignition coil? Anyone have this problem? Where should I start? I just want my car to finally run smoothly with plenty of power.

ih8unow

I had this exact same problem around a year ago and it was a frayed plug wire. I have no idea how it got frayed but it would randomly make one of my cylinders just quit firing. I bit the bullet and did plugs, wire, and a new coil after finding the problem just to be sure.

dawson1112

Why don't you have it scanned to see what code is actually being stored in the computer

bbjack

I didn't think they could scan my car if the check engine light isn't on? It's not on right now. I'll probably go to autozone today and get new spark plugs. I'm being really frugal right now since I just moved across the country and I'm trying to save money to get into my new place. So would like to spend the least I can and have it fixed. Spending money on things that don't fix it would throw me in a hole! At the same time, I need to spend what I can to take car of my car's health.

dawson1112

Yes you can scan the car . When the check engine light flashed ( even if it went back off ) the pcm stored a code as to why it flashed. Every time the check engine light comes on it stores a code. If it comes on or flashes for the same reason then the most recent illumination is stored. I bet you have numerous codes stored to memory .

bbjack

Well I had the diagnostics put on my car today and no codes came back at all. Bought new spark plugs and going to put them in here in a minute and see if that does the trick.

Question... can my problem be caused by a bad o2 sensor or would that cause something else?

corker

"I noticed that in bad rainy weather that the engine will sometimes start misfiring badly. I was on the interstate going 70 mph or so the other day and the check engine light started FLASHING. So I go to neutral and adjust gears and it goes off."

As Dawson said in the post above, those codes should be stored in history. But, the quote I copied above should be a good indication of your ignition system breaking down. With your engine running, spray down all plug wires and coil pack with a spray bottle of water. Snap the throttle a few times and feel for any misfires. Chances are you need new wires or you have secondary voltage leaking from coil pack.
Corky

ih8unow

That is a really good idea about the spray bottle from Corker. I actually found out about my frayed wire by following a suggestion from another thread about popping the hood at night when it's dark and looking for sparks while the engine is running. I could actually see an intermittent arc between the wire and the engine block.

bbjack

Replaced all spark plugs but the problem is still there. My car also idles a bit low. When putting the pedal to the metal, I should have some sort of get up and go on it without it jumping and jerking.

May have to try the spray bottle!

Derf00

You are contradicting yourself. You want to be frugal yet you're already throwing parts at it hoping to fix the problem (spark plugs). What makes you think it's a plug?

If the problem gets worse when it rains I would go with wires before plugs. Plugs would present the problem all the time and not get better or worse when it rains/doesn't rain.

I just noticed this is a 3.8L. Plug wires are a big culprit on these. Go with Motorcraft wires, not aftermarket. Aftermarkets tend to have incorrect bends on the boots which puts them right on the exhaust manifold and burns them out quicker.

Spray bottle trick on the wires will help find the problem wire(s).