long story short. I bought a 98 blazer 4 dr 4x4 from someone who rear ended someone with it. I had to make some repairs including removing the engine to change the oil pan. After I got it back together I have a cylinder 1 misfire and multiple random misfire codes (p0300 and p0301). I swapped #1 spark plug with another to see if it would move to the other cylinder, then swapped injectors to see if it would move. It didn't move with either. I guessing a cam position retard check might fix it. Is there a reason why cylinder 1 would be singled out if its a cam position retard issue? Any way to check it myself? Is it adjusted by turning the distributor? Also, I replaced the distributor cap, rotor, spark plugs and wires. All with ac delco except for the wires. I know this topic has been discussed, but any help would be appreciated

 

Is the number 1 plug actually getting power? you could try swapping one of the cables with another cylinder. If you got cheap wires you may have a wire that is bad.

 

Sounds like you disturbed the timing cover or crank position sensor when changing the oil pan, or maybe the accident disturbed it.

In any case, first you need to decide if the misfire detection system is working correctly or if the misfire codes are false. I would use a scan tool to display the current misfire counts for each cylinder and then pull a plug wire and restart. Misfire counts on that cylinder should go up rapidly. If the induced misfire is not detected correctly, then chances are the misfire code that is setting is false and you simply need to do a crank sensor relearn (or have it done). A crank sensor relearn is not something that cheap scanners/software can do, but there are several Android solutions for well under $40 that can monitor the misfire counts and two will even monitor cam sensor retard on our Blazers). All can use the Bluetooth OBD2 adapter. However for crank sensor relearn, bidirectional communication and much more sophistication is required. Plan on $350 + for software if you want to do it yourself.

Torque Pro - $5.95 (doesn't monitor cam sensor retard)

Car Gauge Pro - $8.95 (1998 up Blazer) Note this software does not filter tests that do not work with your particular vehicle.

Dash Command - $10 + $10 GM enhanced (1996 up Blazer).

Recommend BAFX Bluetooth OBD2 adapter from Amazon.

Good luck and best wishes for a successful repair.

 

I changed the timing cover. Do I need a crank sensor relearn because of that?

 

Yes you do!! Any minute changes in sensor position changes the requirements for misfire detection parameters that are stored in the PCM during a crank sensor learn.

Won't cause an actual miss, but can definitely turn on the SES light and give a false PO30x code. Sounds like what you have, as long as you are not feeling a misfire. If it fails the misfire detection test I gave, then all bets are off on detecting one correctly.

 

Correct, before anything else, get a relearn done. then get cam position sensor done also. will run like a champ and your mileage will go up

 

If you choose to pay someone to check your cam sensor retard at the same time as doing a crank sensor relearn, I would check for wear in the distributor gear before taking it in. Should be no movement at all when you manipulate the rotor back and forth (don't count any up/down movement). If you change the distributor gear or move the distributor at all, it will need to be done again. Better to get your own software to do the cam retard I think. Only $30 for Car Gauge Pro and BAFX OBD2 adapter.

 

Thanks for all the info so far. Hopefully I will get this all figured out soon. It seems like I can feel a little bit of a miss. Hopefully cam sensor retard will fix that. I did have the distributor out to do intake manifold gaskets.

 

You are welcome. Please let us know how things turn out. It's the only way we have to know if our advice is on target or not. A lot of us try to continue to learn through other's experiences.

 

Believe you need to do the crank sensor relearn before the cam shaft