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misfire p302 #2 cylinder

709 views 4 replies 2 participants last post by  mn12v6x2 
#1 ·
OK this is what it has been doing. You start the car cold, and it runs very badly, just like it would if one cylinder was not firing at all. Then you drag the beast down the highway about 2 miles and while you are sitting at the light it will clear up and run smoothly. At that point it is usually gone.
However every once in a while, it will come back an hour later or so. It will just pop up while you are driving down the road. So I replaced the plug to cylinder #2, and the wires. Problem is still there.
I did a splitport motor swap about 10K ago, and haven't had any problems until now. I am also wondering though if there may be a fuel pressure problem and if that could cause it. I was going to replace the coil, but I thought there would be two cylinders misfiring if the coil was bad.
Any ideas?
 
#2 ·
moving forward

I have decided since I don't drive this car much anymore that I will not perform any repairs or testing on the vehicle unless advised through this post. This way everyone knows everything what we have done to get to this point.
And FYI,
I cleaned the mass air flow sensor about 4 or 5 months ago.
I changed the fuel filter about a year ago.
all the sensors on the motor are from the new motor, so they only have about 50K on them.
it does have an adjustable fuel pressure regulator, but no port to read the pressure. I had it set to about 47psi if I remember correctly.
I used the 21lb. injectors out of the new motor w/ a C&L MAF tube. reused sensor

so where do I go next?
 
#3 ·
still there

So yeah, after replacing the plug in cylinder #2 and swapping wires w/ cylinder #1, the problem is still there. I just reset it, took down to have it read, and again p302 misfire on cylinder #2.
I think I will try the coilpack now, before I pull the upper intake and start swapping injectors.
 
#4 ·
Hi, Have you checked the EGR valve? I have somewhat the same problem on my 35th anvi, except it's 2 cylinders. The car will start up fine, drive down the road then my tach drops down to about a grand, no power unless I drop down a gear. It will spirt like it wants to kick in, then it will after a while. We have done a lot of checking and that's what we finally came up with. The EGR valve, the new one goes in today so I will know better later if that is truly the problem.
 
#5 ·
please let me know how it turns out because I have an EGR problem I am already aware of and never thought it would have that kind of effect. I had to make a custom tube and it is now bent because of the AC tube I had routed improperly. Maybe thats where my I should start.
 
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