Pollarican
Well-Known Member
- Joined
- October 10, 2006
- Messages
- 387
- Reaction score
- 5
- City, State
- Wall Township, New Jersey
- Year, Model & Trim Level
- 1991 EB 4dr
So the other day, after reassembling my ignition system for the first time since my A4LD to M5OD trans swap, I tried to fire up the old blue beast. She cranked and kicked over, but she choked out as quickly as she fired. I'm assuming this is because I screwed up my ignition timing while unbolting my torque converter, leaving me with the task of figuring out how to and going about resetting my timing. With the problem stated, here is what the Hayne's Manual has to say on the topic:
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Top Dead Center (TDC) for Number 1 Piston - Locating:
Note: The 4.0 engine is not equipped with a distributor. Piston position must be determined by feeling for compression at the number one spark plug hole, then aligning the ignition timing marks as described in step 5.
1) Top Dead Center (TDC) is the highest point in the cylinder that each piston reaches as it travels up-and-down when the crankshaft turns. Each piston reaches TDC on the compression stroke and again on exhaust stroke, but TDC generally refers to piston position on the compression stroke.
2) Positioning the piston(s) at TDC is an essential part of many other repair procedures discussed in this manual.
3) Before beginning this procedure, be sure to place the transmission in Neutral and apply the parking brake or block the rear wheels. Remove the Spark Plugs. Disable the ignition system by disconnecting the electrical connector from the ignition coil pack, located above the left valve cover.
4) In order to bring any piston to TDC, the crankshaft must be turned using one of the methods outlined below. When looking at the front of the engine, NORMAL CRANKSHAFT ROTATION IS CLOCKWISE.
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a) The preferred method is to turn the crankshaft with a socket and ratchet attached to the bolt threaded into the front of the crankshaft.
b) A remote starter switch, which may save some time, can also be used. Follow the instructions included with the switch. Once the piston is close to TDC, use a socket and a ratchet as described in the previous paragraph.
c) If an assistant is available to turn the ignition switch, to the Start position in short bursts, you can get the piston close to TDC without a remote starter switch. Make sure your assistant is out of the vehicle, away from the ignition switch, then use a socket and ratchet as described in paragraph a) to complete the procedure.
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5) The crankshaft pulley has 35 teeth, evenly spaced every 10 degrees around the pulley, and a gap where the 36th tooth would be. The gap is located at 60 degrees BTDC (Before Top Dead Center). Turn the crankshaft until you feel compression at the number one spark plug hole, then turn it slowly until the sixth tooth from the missing tooth is aligned with the Variable Reluctance (VR) sensor and the TDC notch is aligned with the pointer (Located at the front of the engine).
6) After the number one piston has been positioned at TDC on the compression stroke, TDC for any of the remaining pistons can be located by turning the crankshaft and following the firing order.
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This is the method they have outlined. When reading this, my first question is, How do you feel for compression at the number 1 spark plug hole? Once I feel any compression in that hole, do I simply turn the crank until the 6th tooth from the missing tooth is aligned with the VR sensor to reset my timing?
I believe stock timing is 10 Degrees BTDC. My engine has 120,000 miles on it. Should I try to advance or retard my timing a few degrees to compensate for some compression lost to normal engine wear?
Any input would be appreciated guys, I intend to help others faced with this task based on the knowledge I gain from this experience. Hopefully I can flesh this out a bit to include pictures once I decipher the entire procedure.
--------------------------------------------------------------------------------
Top Dead Center (TDC) for Number 1 Piston - Locating:
Note: The 4.0 engine is not equipped with a distributor. Piston position must be determined by feeling for compression at the number one spark plug hole, then aligning the ignition timing marks as described in step 5.
1) Top Dead Center (TDC) is the highest point in the cylinder that each piston reaches as it travels up-and-down when the crankshaft turns. Each piston reaches TDC on the compression stroke and again on exhaust stroke, but TDC generally refers to piston position on the compression stroke.
2) Positioning the piston(s) at TDC is an essential part of many other repair procedures discussed in this manual.
3) Before beginning this procedure, be sure to place the transmission in Neutral and apply the parking brake or block the rear wheels. Remove the Spark Plugs. Disable the ignition system by disconnecting the electrical connector from the ignition coil pack, located above the left valve cover.
4) In order to bring any piston to TDC, the crankshaft must be turned using one of the methods outlined below. When looking at the front of the engine, NORMAL CRANKSHAFT ROTATION IS CLOCKWISE.
----------------------------
a) The preferred method is to turn the crankshaft with a socket and ratchet attached to the bolt threaded into the front of the crankshaft.
b) A remote starter switch, which may save some time, can also be used. Follow the instructions included with the switch. Once the piston is close to TDC, use a socket and a ratchet as described in the previous paragraph.
c) If an assistant is available to turn the ignition switch, to the Start position in short bursts, you can get the piston close to TDC without a remote starter switch. Make sure your assistant is out of the vehicle, away from the ignition switch, then use a socket and ratchet as described in paragraph a) to complete the procedure.
----------------------------
5) The crankshaft pulley has 35 teeth, evenly spaced every 10 degrees around the pulley, and a gap where the 36th tooth would be. The gap is located at 60 degrees BTDC (Before Top Dead Center). Turn the crankshaft until you feel compression at the number one spark plug hole, then turn it slowly until the sixth tooth from the missing tooth is aligned with the Variable Reluctance (VR) sensor and the TDC notch is aligned with the pointer (Located at the front of the engine).
6) After the number one piston has been positioned at TDC on the compression stroke, TDC for any of the remaining pistons can be located by turning the crankshaft and following the firing order.
-------------------------------------------------------------------------------
This is the method they have outlined. When reading this, my first question is, How do you feel for compression at the number 1 spark plug hole? Once I feel any compression in that hole, do I simply turn the crank until the 6th tooth from the missing tooth is aligned with the VR sensor to reset my timing?
I believe stock timing is 10 Degrees BTDC. My engine has 120,000 miles on it. Should I try to advance or retard my timing a few degrees to compensate for some compression lost to normal engine wear?
Any input would be appreciated guys, I intend to help others faced with this task based on the knowledge I gain from this experience. Hopefully I can flesh this out a bit to include pictures once I decipher the entire procedure.
![IMG_20151014_103920[1].jpg](/forums/data/attachments/67/67708-827d5149dcb5b38dfb1cc4984518b3ea.jpg)
