When you get all done with this nightmare of an oil leak, don't forget..... any time the crankshaft position sensor and/or timing cover is disturbed, removed or replaced, a crankshaft position sensor re-learn must be performed. Only way to do it is with a bi-directional scan tool. The $300 cheapie scan tools the auto parts stores use will not access it. Most auto parts stores don't even sell them, much less rent them out.

 

I have to disagree with you on the case relearn. I did a timing chain and gear replacement on my 96 and I didn't have to do this. As long as the original parts are installed it shouldn't make a difference. I also took a bench grinder and removed the lip off of the bottom of the plastic timing chain cover. It doesn't leak so I leave it alone. I did use new seals and gaskets and put RTV on it.

 

The relearn is absolutely necessary if the crankshaft sensor is disturbed in any fashion. The odds of getting it back where it was are infinitely against you, and with a modification, guaranteed it's incorrect. The crankshaft sensor is a signal generator, its orientation to the reluctor on the crankshaft changes its output. The relearn calibrates the sensor with the crankshaft so the PCM "knows" exactly where the crankshaft is in its rotation. Much like a timing chain being installed a tooth off, the PCM can only "assume" it's correct. After the relearn is completed, camshaft retard should at least be checked, and adjusted if necessary. The combined data from these two sensor adjustments is critical for accurate ignition timing, injector firing, misfire detection and cylinder identification. If the relearn is not done, the PCM uses the original data for crank sensor orientation, and it will not set a DTC if it's incorrect.

 

If I didn't remove the sensor from the housing, I don't see how it would be changed. My 96 has been up and running since November with no problems whatsoever. It does set a SES light but that is from an emissions problem thats it had for a couple of years. I clear the light when it pops up.

 

The crankshaft position sensor is mounted to the timing cover: when the timing cover or sensor are moved, removed, replaced or disturbed in any way, the physical relationship between the sensor and the reluctor changes. If/when this happens, the relearn procedure is required. If the stored crankshaft position variation data is incorrect, it will directly affect ignition timing, injector firing and misfire detection, (junk in, junk out). Ignition timing etc could be off 10 degrees with no DTC's set and your only clue would be poor fuel mileage. The diagnostic flow chart in the FSM for P1336 explains it under "Circuit Description".

 

Captain Hook, would another clue be hesitation/rough firing, especially accelerating from a stop? After the replacement of the timing chain and cover, it ran really well for about 1000 miles. Now it has suddenly begun running roughly. I can feel/hear the misfire on idle, though it stays running. Off the line it clearly sputters/hesitates. At cruising speed it's barely perceptible, but does seem less responsive to throttle changes than it was before.

Your explanation of the need for the relearn seems to finger the likeliest culprit: change in the physical relation between the sensor and the reluctor under the timing chain cover.

But does it make sense that the symptoms only arose after 1000 miles?

Also, do you know exactly what scanner is required to perform the relearn?

 

The symptoms you're describing could easily be caused by the ECM using the (incorrect) data from the old CKP sensor however, IF that were the case, the symptoms would have showed up right from the beginning. For that reason, I would suspect something else, possibly secondary ignition or even a fuel pressure or delivery problem. If there's a noticeable misfire, as you described, the ECM should set a DTC identifying which cylinder is misfiring. If there is no DTC present, check in the history and/or pending file.

As for which scan tools can access the relearn command in the ECM.... I can tell you for certain that the Snap On MT2500, Solus and Modis are all capable of it. Any of the high end scan tools with "bi-directional capabilities" can do it. Maybe other members will chime in on this.

 

I went thru the same thing. It turned out to be a "new" 3 month old distributor cap. it tested good with an ohmmeter but was not firing. A new cap solved the problem. Like it has been said on here many times "new parts fail".

After a while I got real good at taking the top of the engine apart LOL

 

Thanks gentlemen, sorry for the delay. Yes, Captain Hook, the 1000 miles seemed like too long a wait for those effects to make themselves felt, and thank you for those other suggestions. No SES light yet, but I'll definitely check for anything in the pending file. And 96Blazernut, I'd love to find it's just a distributor cap that needs a swap-out! Thanks again.