When your engine was started at the factory for the first time, the computer went through several learning proceedures that are unique to your truck. One of which is the distance the crank sensor is from the reluctor ring on the crank. This distance is learned to.001 inch. As your engine ages, the bearings wear and this distance changes. Normaly the computer can adjust for this, but when you change the sensor sometimes--not all the time--the sensor is a little too far off for the computer to compensate. About 3 out of 10 need a crank relearn done. Crank sensors almost never wear out--what wears out is the main bearings on the crank. Failures of the sensor can be attributed to excessive carbon build up--that's it. Your problem, however, probably is not the sensor. If you can put the old one back in--if not have the relearn proceedure done and check the following in order--1--battery connections voltage drop--no more that.02 volts.2--spark plug gap and condition--replace with A/C Delco only!3--plug wire resistance--30,000 ohms max--replace with A/C delco only!4--Distributer cap and rotor--replace with any brand5--coil--can be tested at autozone or any parts store for free6--ignition module--test at same place for free7--compression test--no less than 10% difference of highest reading and no less that 110 psi at any cylinder.
Also, the distributers' gear usually wears out around 180000 miles. If all the above check out--take the distributer out and check the gear--I'll bet it is worn out if it has never been replaced. Common failure.
Monday, March 3rd, 2008 AT 7:56 PM