Need help checking timing on 4.0L
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Freshman User
Joined: Aug 2003
Posts: 49
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From: Columbus, MS
Need help checking timing on 4.0L
I have a 94 4.0L in my 87 BII. I have a sputter/miss problem during accelaration and have been testing/verifying/replaceing the various sensors on the motor. I installed new plugs and plug wires. The engine runs a bit better but still misses during acceleration (Runs like a bat out of H#*! at full throttle). Now I'd like to at least verify the timing.
Any tips on how to check the timing on a 4.0L? My problem is that there is NO way I can see the timing mark(s) to check the timing using a basic inductive timing light. The air tube is in the way, hoses are in the way, the drive belt is in the way, pulleys are in the way, and the fan blade is in the way.
I know the PCM controls the timing and that I can't adjust it. I would like to verify the PCM is doing its job correctly.
Thanks for any help!
Mark
Any tips on how to check the timing on a 4.0L? My problem is that there is NO way I can see the timing mark(s) to check the timing using a basic inductive timing light. The air tube is in the way, hoses are in the way, the drive belt is in the way, pulleys are in the way, and the fan blade is in the way.
I know the PCM controls the timing and that I can't adjust it. I would like to verify the PCM is doing its job correctly.
Thanks for any help!
Mark
Postmaster
Joined: Dec 2001
Posts: 3,742
Likes: 2
From: UT
Here's a thread I started a month or two back:
https://www.ford-trucks.com/forums/s...hreadid=147749 I concluded that my problem was indeed in the harmonic balancer/crankshaft pulley assembly, and haven't worried about it since. What apparently can happen is that the outer "ring" (which has the timing marks) can rotate around on the rubber ring. One thing I determined is that it may be important to manually find TDC and verify that the timing marks on the "pulley" are correctly aligned.
The first time I checked mine, I removed the air intake tube to free up some space. That was enough to see the timing marks. Having done it a couple of times, I think I could do it now with everything in place, but it is real tight.
Don't forget to disconnect the SPOUT wire while checking the base timing at idle.
If you want, you can also check the computers timing advance calculations. Between the engine id output and the dynamic response pulse, the engine revs up and the computer checks the timing advance by running at base + 10° (30°) BTDC.
https://www.ford-trucks.com/forums/s...hreadid=147749 I concluded that my problem was indeed in the harmonic balancer/crankshaft pulley assembly, and haven't worried about it since. What apparently can happen is that the outer "ring" (which has the timing marks) can rotate around on the rubber ring. One thing I determined is that it may be important to manually find TDC and verify that the timing marks on the "pulley" are correctly aligned.
The first time I checked mine, I removed the air intake tube to free up some space. That was enough to see the timing marks. Having done it a couple of times, I think I could do it now with everything in place, but it is real tight.
Don't forget to disconnect the SPOUT wire while checking the base timing at idle.
If you want, you can also check the computers timing advance calculations. Between the engine id output and the dynamic response pulse, the engine revs up and the computer checks the timing advance by running at base + 10° (30°) BTDC.
