I just recently swapped in an old '96 D1 4.0 engine into my '03 D2 that had a 4.6.
The 4.6 had a crack behind the number 5 cylinder wall, causing pressurization of my cooling system.
Other than the overheating caused by the cracked block, the 4.6 ran pretty good with no misfires, vacuum leaks, etc...
The first 100 miles on the 4.0 in the '03 D2 were pretty good. Ran smooth, power was okay. Just had some vacuum leak codes and of course SAI errors, as I left the 4.0 heads and plugged the vacuum lines.
Right at around 100 miles, I started getting misfire codes on #3 cylinder, after a little while longer I actually started feeling the misfires.
The misfire codes have now progressed to include #3, # 5 & occasionally #7, with a p1300 popping up sometimes, and the odd plugs are covered in a dry, black soot. Even plugs look good.
The plugs, wires, coil packs and O2 sensors are all less than a few hundred miles old.
Compression on the cylinders is around 165.
I replaced the air filter and swapped in an old MAF I had, from a troubleshooting session two years ago, where the MAF proved to not be the problem, so I'm assuming it's good.
No change, still have mis-fires.
I had a similar situation on my Jeep Wrangler 4.0 that turned out to be burnt valves, so I'm leaning in that direction at this point.
The 4.0 has about 71,000 miles on it.
Before I take the heads off, do you all have any ideas or suggestions I might look at?
Thanks.
The 4.6 had a crack behind the number 5 cylinder wall, causing pressurization of my cooling system.
Other than the overheating caused by the cracked block, the 4.6 ran pretty good with no misfires, vacuum leaks, etc...
The first 100 miles on the 4.0 in the '03 D2 were pretty good. Ran smooth, power was okay. Just had some vacuum leak codes and of course SAI errors, as I left the 4.0 heads and plugged the vacuum lines.
Right at around 100 miles, I started getting misfire codes on #3 cylinder, after a little while longer I actually started feeling the misfires.
The misfire codes have now progressed to include #3, # 5 & occasionally #7, with a p1300 popping up sometimes, and the odd plugs are covered in a dry, black soot. Even plugs look good.
The plugs, wires, coil packs and O2 sensors are all less than a few hundred miles old.
Compression on the cylinders is around 165.
I replaced the air filter and swapped in an old MAF I had, from a troubleshooting session two years ago, where the MAF proved to not be the problem, so I'm assuming it's good.
No change, still have mis-fires.
I had a similar situation on my Jeep Wrangler 4.0 that turned out to be burnt valves, so I'm leaning in that direction at this point.
The 4.0 has about 71,000 miles on it.
Before I take the heads off, do you all have any ideas or suggestions I might look at?
Thanks.
