This is topic misfire codes in forum Tech Talk at Northern California Ford Owners  .


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Posted by venommS (Member # 7837) on 2008-07-17 04:51 PM :
 
Anyone experience misfire codes on a 96-98 cobra? I have a 96 cobra blown and I keep getting the 300 302 305 codes. What would cause this besides a bad coil or wires. I'm also running autolite 103's at .038.
 
Posted by 93ReefBlue5.0 (Member # 5780) on 2008-07-17 05:24 PM :
 
it could be the coil, plugs, wires... switch the coils from side to side... if the codes follow it, the coil is bad...

p0300 is a random misfire, p0302 and p0305 are misfire cyl 2 and 5... just in case you didn't know..

[ July 17, 2008, 05:26 PM: Message edited by: 93ReefBlue5.0 ]
 
Posted by gtowned (Member # 8156) on 2008-07-17 06:16 PM :
 
check for vacuum leaks.very common to get 0300 with vac leaks.if you do have one it will be near cyl 2 and 5 based on your getting 302 and 305 codes
 
Posted by venommS (Member # 7837) on 2008-07-17 08:11 PM :
 
Thanks, I'll try those suggestions out and post what I find out.
 
Posted by venommS (Member # 7837) on 2008-07-17 09:29 PM :
 
So I switched the coils (side to side) and the same codes are present 300 302 305. I then swapped the original motorcraft coils with the MSD coils I currently had on my car and the same misfire codes are present. I did not clear the DTC codes because it usually takes awhile for them to return. Also last night at the track during a run a CEL came on, I checked it and it was code 1000 which is OBDII not ready. Why would that code be present. Any further suggestions? [Confused]
 
Posted by 93PONY (Member # 60) on 2008-07-17 11:04 PM :
 
http://home.comcast.net/~miracerros/dtc_powertrain_1.htm
http://home.comcast.net/~miracerros/dtc_powertrain_2.htm
 
Posted by venommS (Member # 7837) on 2008-07-17 11:42 PM :
 
Thanks Shaun! I guess the 1000 code came because I did clear the DTC prior to running at the track last night. I'm still trying to diagnose the misfires but have come up empty so far. Would clogged or fouled injectors cause a misfire. Or is it possible the EGR is stuck open?
 
Posted by 93PONY (Member # 60) on 2008-07-18 01:34 AM :
 
Hard to say.
You did have an EGR issue. Possibly a short that did something? I don't even know how to test for that.
Also could be injector or ignition drivers in the actual computer. I've seen this before, but typically you don't get a code.....since the computer doesn't pick up an 'miss' till it's missing 40% of the time. We can tell right away when there's one or more cylinders dropping without needing a code to be thrown.

Whatever it is, it's real since your ET/MPH is so low for 400RWHP. (or you're just a really bad driver. [Wink] )
Strangely, when I had the car & cleared the codes, the car did not physically have a miss. It drove great. Both PT & WOT. It felt like a mid/low 12 second car. (once it got up into the RPM's & made boost).

My opinion is that it's electrical. The codes I pulled & cleared when I had the car included 2 others (P0304 & P0308 & believe). so 2 cylinders from either bank. This eliminates a coil pack, as both would have to be 'bad'. There's 2 EMI/RFI filters next to each coil pack. I don't know what would happen if they were not working correctly.

This is a tough one. I'd recommend taking it to a good electrical shop like California Rewire. Luckily, a problem like this should be easy for them to find since they can put high load to the ignition system without driving the car or going WOT.
 
Posted by 93PONY (Member # 60) on 2008-07-18 01:37 AM :
 
BTW, keep a close nose on the dipstick. The last thing you want is raw fuel mixing with the oil because it's not being burned due to a misfire.

Fuel in the oil can be detected by sniffing the dipstick shortly after the car has been running (& missing).

Fuel in the oil = no good!
 
Posted by venommS (Member # 7837) on 2008-07-18 02:46 AM :
 
I will keep an eye out for that thanks! I was trying to check some of the obvious things before bringing it to the shop you suggested, but the more you mention it the better it is sounding. I think I'll give them a call in the morning.
 




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