Ok, i was reading in the S10forums and here about PCM tunes and something came up about getting a crankshaft posistion sensor relearn?? And that got me thinking about my situation with my distributor when i put in my rebuilt engine. We had to stab the distributor 2 teeth retarded just to get the engine started without kicking back on the starter. Runs just fine but i do notice some sluggish performance and i only got 9-11 MPG. Im deffinatly going to get a tune for my new blazer, but should i do the relearn too?

Also, what do you think is the best place to get a tune:
Blackbear performance
Wait4me
PCM4Less
other

 

If the timing cover is removed, do not reuse it, replace it. If the crankshaft position sensor is moved, removed, replaced or disturbed in any way, including moving the timing cover, the crankshaft position sensor relearn is necessary. If the distributor is removed, camshaft retard should at least be checked, and adjusted if necessary. Both of these operations require a scan tool. It must be capable of initiating the crankshaft position sensor relearn, as well as accessing camshaft retard. The el cheapo, ($400 or $500) scan tools that the auto parts stores use, are not capable of either procedure.

 

Gotcha, so most likely after i get the relearn i will not have these problems?? There's no way to "set" the timing dead on, because its a computer problem not a timing problem correct?

 

Possibly, but probably not. The relearn is done to "sync" the sensor with the crankshaft so the PCM "knows" exactly where the crankshaft is in its rotation. The sync data is burned into the PCM during the relearn. If the sensor is moved, replaced, removed, etc etc, the sync data that was burned in from the previous relearn is now incorrect. The engine will usually still run using the old data however, injector timing, ignition timing, cylinder misfire identification, etc etc most likely will be incorrect, (incorrect data in, incorrect data out). After the relearn, camshaft retard should be checked and adjusted. Correct camshaft retard assures that the correct amount of ignition advance is actually applied.