1999 Blazer Crankshaft Sensor Selection

[TCGrove]

Cold weather is upon us again and my 99 Blazer is starting to have a misfire. I had the same problem last year in cold weather. I get a code P0304 (Misfire on cylinder 4). Last year..cleaning the MAF seemed help. I've read all the posts....I've started down the line again...plugs, wires, rotor, fuel injector, fuel filter, etc... I came across a post in which someone replaced their crankshaft sensor and it solved their misfire problems. My question is what sensor do you buy? There is a huge cost difference from $58-$139. I was looking at NAPA and Advanced Auto Parts. Some parts I can see paying more for better quality parts, but this thing is basically a magnet.

[old_master]

The crankshaft position sensor is more than likely NOT the problem. It is common to ALL cylinders and would set a DTC if it malfunctions. P0300 series DTC's are usually caused by secondary ignition problems, ignition coil, spark plug wires, spark plugs, distributor cap and rotor. On your list of parts, did you replace all of these trying to repair the P0304? Did you replace the distributor cap? Have you removed the #4 spark plug and checked it for wet, unburned fuel? Have you checked fuel pressure and leakdown?

[TCGrove]

I just wanted to follow up on the misfire on cylinder 4. It was the distributor cap. I replaced the plugs first and the problem was almost worse. This included the PITA #3 which I just pulled the orange steering sleeve back and used a cut off long socket. THe plugs looked worn but not bad. On the distributor cap you could see where it had been hot (burnt look) along the #4 wire as it passes through the top of the cap. The rotor and contact points were pretty shot too. My 99 Blazer has 150,000 miles on it and the distributor, rotor, plugs, and wires had about 40,000 on them.

[MT-2500]

Always use AC Delco cap and rotor and plugs.
After it is running good check camshaft retard setting on a good engine capable scanner.
If not close to - or + one degree reset it.