Misfire on startup
 

Once and a while, I get two codes after starting the truck up. P0300, and P0316.

One says "Random/Multiple Cylinder Misfire Detected", and the other says "Engine Misfire Detected on Startup (First 1000 revs)".

Now the truck doesnt have a miss when driving, or even when idleing. I can't feel any atleast. It seems to just be an issue with startup I imagine. I recently got the screamin demon coilpack in the last month, but even before I got it, I would still get the same codes on startup once and a while. Lately it just seems to be getting a little more frequent. When I got the coilpack, I put a new set of autolite double platinums in, and gapped them to .65 like it said. I already had underdog wires, so I just reused them. The wires have about 30K on them now. Im not sure what I should try, maybe a brand new set of wires and copper plugs? Im just curious if anyone else has this problem. Any help is greatly appreicated.

Thanks

I just replaced my coil pack because of a misfire code from my 6th cylinder. I had noticed that my 6th plug was wet so I knew it was an electrical issue and not a fuel issue. I replaced my plugs and wires but that didn't solve the misfire. The last step was replacing the coil pack which in turn corrected the issue. I would look into your coil pack. If you still have your old one, before the demon coil swap, just put it back in and see if it misfires at start-up.

Replace the Screamin Demon with the OEM coil pack, and properly gap the new plugs.

Take note of this from NGK:

"With this mind, many think the larger the gap the better. In fact, some aftermarket ignition systems boast that their systems can tolerate gaps that are extreme. Be wary of such claims. In most cases, the largest gap you can run may still be smaller than you think."

Well, it doesnt do it everytime, and it must only be on startup because I can't even feel a miss when driving or even idling. This would happen once and a while even before the coil swap. It never comes on when driving, just right after start up once and a while.

Lol, obviously they didn't read all of the post. If your old coil pack did it too, I doubt that is the issue. To me, Id say its the plugs. I know autolites are supposed to be made by Motorcraft, but as a mechanic, I have seen several instances where a new model Ford didn't run well on Autolites. I would highly suggest going and getting a set of OEM Motorcraft plugs. You don't have to go to the dealer to get them, they are available at O'reillys for sure. If I understand you correctly, you did change the plugs before this problem showed up?

Autolites and Motorcraft plugs are both made by Honeywell, an Allied Signal company.

Well, whatever. The point is still the same, they are both made by the same company. I would still try a set of motorcraft plugs in it and see if that helps. Do what you want, but Im speaking from experience here, and thats where I would start if I was in your posistion.

It very well could be a fuel issue also. I was getting multiple cylinder missfire codes. I had the injectors cleaned. One was clogged, I think another had a cracked o ring. the rebuild fixed it up.

Hey, sorry guys I havent been back to reply because of power being out and stuff. Yes, I did replace the plugs when I put the new coil pack in. I forgot to mention, the last time I did it, it also had a code that said something about "more driving required" or something. I let it go this time, and didnt clear the codes. Today, the check engine light went out by itself. I'll let it go until it comes back on, and I guess go from there.

Oh yeah, did your codes come back as misfire on startup?

it threw several. all were missfire. Something like

random cylinder miss fire
multi cylinder missfire

yeah same here, I changed the fuel filter not long ago, so im just trying to figure out the first thing I outta try next.

Something cheap to try is regap plugs to factory specs. You can get to the point where the gap gets too big and will create missfires. Its easy to think you are at .065 but in reality you are at .07+. In addition, as you get higher in mileage the plugs gaps will get larger on their own, pushing it past what the coil pack can handle.

yeah ill try that, I was just afraid if I gapped to factory specs, the screamin demon might burn them up faster? I could be totally wrong here, im just not familer with it.

One more time from post #3:

Take note of this from NGK:

"With this mind, many think the larger the gap the better. In fact, some aftermarket ignition systems boast that their systems can tolerate gaps that are extreme. Be wary of such claims. In most cases, the largest gap you can run may still be smaller than you think."


Another thing to keep in mind, with DIS, and EDIS there are 2 plugs in series, so the effective plug gap would be 0.13", if each plug is gapped at 0.065"

plugs are gapped back to stock spec, so ill see what happens.

Well, the other night when I gapped them back to stock, I cleared the codes. Yesterday, the same two came back. I would hate to think it would be an injector problem since it only has 63k miles on it. Again, its just throwing those two codes I mentioned in the first post, and one is saying its on startup. It doesnt actually feel like it has a miss when driving it, or just sitting there.

aside from bashing the aftermarket parts (some of us dont see the point of bashing), have you noticed any coolant loss?

you may have a cracked head. what happens is this, when the engine cools the crack opens and allows coolant to get into the combustion chamber, when you start the engine the coolant gets burned causing the misfire at start up. as the engine warms the head heats up and the metal expands thus sealing the crack.

i'm surprised the "ranger" gods have not post the TSB on this or any of the "useful" information i posted.

this is what i would do, let the engine cool overnight, remove all the spark plugs, then use a cooling system pressure tester, pressurize the system to 13-16 psi, watch the gauge on the tester, if the pressure drops then look for coolant in the cylinders.

I havent noticed any loss in coolent, I recently changed it though, but its always at the full line when cold. I'll keep an eye on it though, I hope that isnt the case, that is a horrible thought.

Update: Tonight I put the factory coil pack on, and the plugs are regapped to stock spec. Before the aftermarkert coil pack, ive had that code only happen twice that I remember. The first time was when I got the truck, I started it up one morning and my foot slipped and hit the gas and it set the code off, cleared it and it never came back for over 2 years. I remember one morning it did it to me one other time more recent (before coil pack swap). When I did the coil pack, I also changed the plugs, as the old ones looked worn out. This might be a shot in the dark, but maybe it just needed plugs, and when I did the coil pack at the same time, it could have just caused the same codes to appear. If it comes back, I might try to seafoam the truck, and clean various sensors, and as much as I hate the though of it being an issue, do what 04 Edge said and pressure test the coolent system.

Well last weekend, I cleaned the MAF, and the cleaned inside the throttle body area using the correct cleaners for each one. I went ahead and installed a new set of wires. Between doing those things, the code hasent come back.

gonna bump an old thread rather than start a new one.. ive had all these same issues on my 3.0. same 2 codes, ive changed the plugs (motorcraft), wires, coil pack, cleaned the MAF, the IAC, changed the fuel pump and filter, and still get it occasionally. thinking that running my starter alot more in the few months where my fuel pump was bad (and required more cranks to start) has wore out the starter and that could be causing my codes? help me figure out what to check next.