I have a 2006 Raider Durocross that is misfiring and I'm trying to figure out if there is something else I could do/check before putting it in the shop. I've tried cleaning the thottle body and used some Seafoam in the gas tank. I have changed all the spark plugs, tried swapping coil packs, and swapped fuel injectors. No matter what I do, it stays in cylinder 4. I verified that the spark plug is sparking and the fuel injector is getting a signal from the pcm. Any ideas???

 

Vacuum leak? Had a misfire on a Ford that nobody could figure out. Tried everything I could think of to fix it. Finally took it into the dealership. Took the dealership 4 hours, every mechanic in the shop, and a call to Detroit to figure it out. It was a Vacuum leak.

 

I did take it to the Mitsubishi dealership....and they told me that if i changed all 6 coil packs, the problem would go away. Even after I told him that I already swapped coil packs with 2 other cylinders AND swapped fuel injectors. He said I needed 6 new spark plugs too....even though I changed them not even 2 weeks ago. He said that they "were probably aftermarket so they were probably wrong" and "that I probably gapped them wrong" even though I bought them gapped to oem specs. On top of that, I needed a throttle body cleaning and fuel injector cleaning. Again.....something I already did. Then the price. For the "low bargain price" of $850 I could have all of it done....6 plugs, 6 coil packs, throttle body cleaning and fuel injector cleaning. Needless to say, I wont be returning.

 

and it probably would not fix the problem.

 

I tried to be polite in telling him that it wouldnt fix the problem.....but he assured me several times that it would. Every time I had a logical explanation for why it wouldnt, all he could say was...."BUT, if you change all 6 of them, it WILL fix it." After telling him that I didnt want this to be a parts changing game at the expense of my wallet, he proceeded to tell me that "at this point, thats about all that we can do to fix it." I even asked him that if I DID change all 6 packs and plugs and it didnt fix that problem, what would be next? He wouldnt even answer that....just kept regurgitating that replacing all 6 would fix it. Somewhere in all this, he told me that my truck is really a Dakota (which I already knew) and his guys "dont really work on these" and he wanted his Dodge guy to look at it. Its nice knowing that they cant even work on something with their name on it. If I DO take it back to any dealer, at least I know to go to Dodge.

 

When my Ford was misfiring I did pretty much everything you did, new plugs, new plugs wires, everything that should fix it and nothing did. Finally took it to a local, non-dealership, auto shop. After having told them I had already changed the plugs and so on, they proceeded to replace and do the exact same things I had. Still didn't work. One of their guys comes out and tells me they have a guy who was a Ford mechanic for 20 years, and he couldn't figure it out, I was going to have to take it too the dealership. At least they were nice enough to only charge me for the parts, not labor, since they couldn't fix it.

I take it too the dealership. I tell them the story, I replaced the plugs etc etc. The service rep asks me if I had used "Motorcraft" plugs. When I told her no, she said "Well that's probably your problem. You should only use Motorcraft parts in Fords." I don't remember what type of plugs I had used, but they weren't cheap off brand plugs. So I end up sitting at the dealership for 4 hours. At some point the service rep comes out and tells me they have every mechanic they have looking at it, they're pulling their hair out trying to figure it out, they've replaced and done everything that should fix it, and nothing's working. After 4 hours the service rep said they finally had to call the Detroit hotline, and they told them to look for a vacuum leak. Because of the vacuum leak it couldn't get enough fuel into every cylinder. They replaced the vacuum hoses, problem solved. I had never heard of a vacuum leak causing misfires. Apparently neither had all of the mechanics that looked at it.

 

You said you checked that the plug is sparking did you do that using the #4 coil while it was attached to the truck? I'd suspect something exclusive to #4, wiring to coil, the plug for the coil. Does the idle/running strategy still reset in these when you d/c the battery? Maybe worth a try, doesn't cost anything. Also maybe a flaming paper bag full of poo left on the desk of the guy you talked to at the dealership.

 

blown head gasket, water could be dripping into the cylinder, also the gound wire for the coil pack might be shot. or have a slight tear causing it to short out on the engine

 

I hate to say it, but the mechanics at that dealership are idiots, that is the FIRST thing I check on fords. For some reason, every other manufacturer has put in some kind of management for a vacuum leak. Ford has not. Take my 95 1500 and pull a large vacuum line. Do it on any older Vacuum Distributor engine, any Chevy. It will automatically idle at a much higher speed to compensate for the leak.

Fords on the the other hand, will loose idle speed as they try to stay running with the vacuum leak, mis-firing the whole time, and sounding like general crap. The lager the leak the lower the idle. You can make a 2.3l 4cyl ranger sound like a MASSIVE CAM V8 simply by pulling a vacuum line or two.

9/10 on a ford IME, it is a PCV valve grommet that has lost its flexibility and allows air to leak by the valve in rather mass quantities. So far off the top of my head, I have fixed a Ranger, a Crown Vic, a Bronco, an Explorer, and as escort simply by finding the PCV valve and wiggling it in its grommet, if its loose enough that you can take it out without pulling with hardly any force, it needs to be replaced.

But now, you know!

 

haha, i can second that. My 92 ranger had vacuum leaks all over and idled crazy. I did an awesome patch job and straghtened it out nicely.