Troubleshooting a miss 94 5.2 mag
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Joined: Apr 2010
Posts: 87,467
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From: Clayton MI
That would be the head itself. Something these heads are notorious for.
The problem you are running into, I think... Is the misfire get more pronounced the more load on the engine. In O/D, you have a DIRECT mechanical connection from the engine, to the rest of the driveline, so, any little problem gets magnified as soon as the trans hits O/D. I did a tuneup on my 96, and misrouted two plug wires, so, I had two cylinders misfiring. In the lower gears, it wasn't really noticeable. but, as soon as the trans hit O/D, it felt like the truck was trying to shake itself apart.
Leakdown test will tell you where the pressure is going. You will actually be able to HEAR it. A valve problem becomes quickly apparent with this test.
The problem you are running into, I think... Is the misfire get more pronounced the more load on the engine. In O/D, you have a DIRECT mechanical connection from the engine, to the rest of the driveline, so, any little problem gets magnified as soon as the trans hits O/D. I did a tuneup on my 96, and misrouted two plug wires, so, I had two cylinders misfiring. In the lower gears, it wasn't really noticeable. but, as soon as the trans hit O/D, it felt like the truck was trying to shake itself apart.
Leakdown test will tell you where the pressure is going. You will actually be able to HEAR it. A valve problem becomes quickly apparent with this test.
