Captin Hook, deffinatley looking in to it more, but just off the top of my head if there was no tone ring wouldn't that in turn through a code for a bad crank position sensor as there would be nothing for it to read ? seems that if feasible installing a tone ring would be a better choice then rewiring the distributor ?

 

Good call! The PCM monitors the crankshaft position sensor all the time, even while cranking. It would definitely set a DTC without a tone ring. When you first got the 95 engine, did the plug wires attach to the distributor cap horizontal or vertical? And, did it have a crankshaft position sensor in the timing cover?

 

pretty sure its was a hei distributor but it was a short block so im not positive ,but definitely no crank position sensor.. on the old cover , we put a new timing chain/timing chain cover and new crank sensor in.. but im not getting a ckp code ? so but the more we talk about it the more im sure it was a hei. kinda lost on what my next step should be.. as far as what i can check and do on my own.

 

Since I'll be replacing my engine soon, I've been following this thread to enlighten me on the "relearn" Cpt Hook has mentioned so many times. I went to the autozone website and came upon this generic definition of the "Engine Control Computer":

"The engine control computers job as part of the ignition system is to use the signals that it receives from the camshaft position sensor, crankshaft position sensor and the knock sensor to determine exactly when to command the ignition module to fire the ignition coil"

Though this is very generic, would the fundamentals be the same....meaning...suppose your crankshaft sensor is good to go and maybe the camshaft sensor is the one out of whack or not working? Thereby the ECM will not give the order to "fire"?

I really don't know anything when it comes to these sensors and the need to "relearn". Since your stuck, just thought another perspective might be helpful in someway.

 

The generic description is "mostly" accurate. The PCM uses crankshaft position sensor data to determine exactly where each piston is in it's cycle, (intake, compression, power or exhaust) in degrees of crankshaft rotation. The crankshaft position sensor, MAP, MAF, TPS, ECT, KS & IAT are all used in determining what amount of ignition advance should be applied. After gathering and processing all of the data, the PCM determines when to fire the ignition module, which in turn fires the ignition coil. The PCM uses camshaft position sensor data for detecting cylinder misfire and accurately identifying which cylinder(s) are misfiring, that's it. Provided camshaft retard is adjusted correctly, the engine will start and run normally even if the sensor is disconnected.

The crankshaft position sensor emits a magnetic field. It directs the field "in the general vicinity" of the tone ring on the crankshaft. There are 3 teeth on the tone ring, each tooth represents two cylinders, (two crankshaft revolutions required for all 6 cylinders to complete each of its 4 cycles). As the teeth on the tone ring pass through the magnetic field, the sensor sends a pulse to the PCM. Depending on each individual crank sensor, and how it is oriented in the timing cover, the magnetic field is not in the exact same position on each engine. During the relearn, the crankshaft position sensor "tells" the PCM exactly where the tone ring is in relationship with the field. Think of the relearn as establishing a "benchmark" from where all PCM calculations are based. If benchmark is not accurate, none of the commands from the PCM will be correct.... typical computer, feed it wrong information and you'll get wrong information out of it. New, remanufactured, reprogrammed, reflashed etc etc PCM's have a default value burned into the crankshaft relearn data file. The engine will at least start and run from this data, and sometimes they run pretty decent too, but, the data is not correct. During the relearn, the new data overwrites the default data and the sensor is synchronized with the crankshaft. Disconnecting the battery has no affect on the data, it remains there until the next relearn is performed.

This is why the relearn is mandatory if/when: the crank sensor or timing cover is moved, removed, replaced, or disturbed in anyway or, the PCM is replaced. If it's not done, the PCM will use the relearn data from the last relearn, which is now, incorrect data.

In post#5 there is an image of the tone ring, it's probably 4" or so in diameter: After the timing chain and gears are installed, the tone ring slides onto the crankshaft, then the timing cover is installed. Do you remember installing the tone ring?

 

Capt,
Where can I get the crankshaft position sensor relearn done?
I just put a 1999 4.3 in my 2000 but havent been able to get it started yet as soon as I get it started is when I get the "relearn" done?

 

The engine must be running. During the relearn, engine RPM is manually brought up to 4000, at that point, the scan tool takes over throttle control. Start to finish, the whole thing takes maybe 15 minutes, which includes 10 minutes to locate and connect the scan tool Must be done with a capable scan tool, not necessarily a GM dealer, but they can also do it. Call around to some local shops and find one that has the equipment, and is familiar with the procedure.

 

Captin hook thank you so much man i cant begin to explain how much headache you saved me pulled the water pump timing cover sure as hell ho reluctor ring $13 through gm.. the 95 motor with a hei never had it.. but after much work putting everything back together she fired right up.. shes a little rough on the idle but we still need to go back through and check compression and valves but after the rebuild the sign of life is better then expected just need to finish the exhaust assembly as well but she should be back on the road sooner then later !!!!!!!!!!!!!

 

there is a work around on the relearn but gm here quoted me $85 to do it better to let gm do it better on the motor and gas mileage

 

Cool! Glad I could help. Get the relearn done, and as long as you're there, ask if they can check & adjust camshaft retard as well.