Okay, 2003 Mustang GT, 4.6L. Completly stock outside of transmission. Last week, threw codes for engine misfire, changed out ignition coils and spark plugs and issue seemed to go away at idle, however I didn't get a chance to drive it that day due to snow. Finally took it out today, seemed okay at first, but then seemed like it still had a little bit of a misfire (I will also mention that a few of the electrical connectors for the ignition coils did break when they were removed, but were still making good connection from what we could see, as I've seen this happen on many 4.6L's that run fine)but anyway, the misfire seemed very minor at first. Eventually I shifted into 5th at around 45-50 MPH, which dropped the RPM's to around 1000-1150 or so. At this point, the shifter itself started shaking violently, along with the engine, tranny (from what I could feel) and pretty much the whole car in general. As soon as I put the clutch in, it stopped, and I didn't notice it in any other gear unless I shift early and the RPM's drop. Never felt a misfire this severe before, and its not throwing any engine lights or anything like that. Any idea's? Thanks!
Help me out with this Ford 4.6 problem
- Thread starter renegade_987
- Start date
- Status
Was there any coolant present in the spark plug wells?
Using all Motorcraft parts? I work on a few Mod-engine Mustangs.....They don't like aftermarket coils from what I've experienced.
Originally Posted By: bdcardinal
Was there any coolant present in the spark plug wells?
None present in the wells that I could see, although I did notice this morning that it has developed a coolant leak, although I haven't had time to see exactly where its coming from yet.
Originally Posted By: clinebarger
Using all Motorcraft parts? I work on a few Mod-engine Mustangs.....They don't like aftermarket coils from what I've experienced.
Motorcraft coils and plugs
Was there any coolant present in the spark plug wells?
None present in the wells that I could see, although I did notice this morning that it has developed a coolant leak, although I haven't had time to see exactly where its coming from yet.
Originally Posted By: clinebarger
Using all Motorcraft parts? I work on a few Mod-engine Mustangs.....They don't like aftermarket coils from what I've experienced.
Motorcraft coils and plugs
Didn't happen to reuse old cop boots, did you? What plugs went in, and how were they gapped? What was the engine rpm when this shaking occured? Possible IAC issue? How old is fuel; possible phase separation or bad gas fill up? Are you sure the clutch is disengaging fully?
Also, not sure about your model year but can you run a mode $06 diagnostic to see the misfire count?
edit: re-read your post I saw the 1100 rpm 5th gear note and what not. Would love to see the mode $06.
Also, not sure about your model year but can you run a mode $06 diagnostic to see the misfire count?
edit: re-read your post I saw the 1100 rpm 5th gear note and what not. Would love to see the mode $06.
Last edited:
Miss under heavy load can be caused by a weak spark.
Originally Posted By: buck91
Didn't happen to reuse old cop boots, did you? What plugs went in, and how were they gapped? What was the engine rpm when this shaking occured? Possible IAC issue? How old is fuel; possible phase separation or bad gas fill up? Are you sure the clutch is disengaging fully?
Also, not sure about your model year but can you run a mode $06 diagnostic to see the misfire count?
edit: re-read your post I saw the 1100 rpm 5th gear note and what not. Would love to see the mode $06.
Nope, didn't reuse boots at all, all new. Motorcraft platinum plugs, gapped at .55
Didn't happen to reuse old cop boots, did you? What plugs went in, and how were they gapped? What was the engine rpm when this shaking occured? Possible IAC issue? How old is fuel; possible phase separation or bad gas fill up? Are you sure the clutch is disengaging fully?
Also, not sure about your model year but can you run a mode $06 diagnostic to see the misfire count?
edit: re-read your post I saw the 1100 rpm 5th gear note and what not. Would love to see the mode $06.
Nope, didn't reuse boots at all, all new. Motorcraft platinum plugs, gapped at .55
Originally Posted By: JimPghPA
Miss under heavy load can be caused by a weak spark.
concur. could be a weak coil. in the past it would be arcing wires, cracked plug insulator, weak coil, weak cap and rotor.
So the coil is either weak, or the high tension path is arcing out before it reaches the plug.
-m
Miss under heavy load can be caused by a weak spark.
concur. could be a weak coil. in the past it would be arcing wires, cracked plug insulator, weak coil, weak cap and rotor.
So the coil is either weak, or the high tension path is arcing out before it reaches the plug.
-m
Last edited:
Originally Posted By: renegade_987
Originally Posted By: bdcardinal
Was there any coolant present in the spark plug wells?
None present in the wells that I could see, although I did notice this morning that it has developed a coolant leak, although I haven't had time to see exactly where its coming from yet.
Start here. pay special attention to the number 4 and number 5 cylinders for leaks from the intake manifold. It likes to crack at the heater core outlet nipple and below the t-stat. When the leak floods the plug wells, misfire ensues.
Originally Posted By: bdcardinal
Was there any coolant present in the spark plug wells?
None present in the wells that I could see, although I did notice this morning that it has developed a coolant leak, although I haven't had time to see exactly where its coming from yet.
Start here. pay special attention to the number 4 and number 5 cylinders for leaks from the intake manifold. It likes to crack at the heater core outlet nipple and below the t-stat. When the leak floods the plug wells, misfire ensues.
- Status
Similar threads
