What do you mean by junk in junk out? lol I only did the Camshaft relearn and the truck has been fine since, I've 200 miles on it and no misfire and such not. I'm hoping my gas mileage will increase, because 14 - 15 mi to the gallon sucks. I've got another question for you, have you ever heard of the gas gauge being a quarter of a tank off? IE when your full, your full. But when you just at the full line your actually at a 3/4 of a tank, and when your at a 3/4 on the gauge your actually a half a tank?

 

Junk in, junk out means if you supply the PCM with bad information, it will send bad information out.

There is no relearn for the camshaft position sensor. Adjusting camshaft retard synchronizes the camshaft position sensor with the exact position of #1 cylinder on the compression stroke.

The crankshaft position sensor relearn synchronizes the sensor with the crankshaft #1 cylinder on the compression stroke.

Both are called "position sensors", they tell the PCM exactly where each shaft is in its rotation. Much like the throttle position sensor tells the PCM the exact position of the throttle plate. Each position sensor must be reporting correct data to the PCM so the PCM can control the engine performance properly.

If camshaft retard is incorrect, ignition timing, along with some other functions, will be incorrect. If the crankshaft position sensor is not synchronized, injector timing, injector pulse width, ignition timing, and most of the things the PCM controls will be incorrect.

Fuel gauge accuracy is determind mainly by the fuel level sending unit and the symetry of the fuel tank. The float arm in the tank can be adjusted, but due to the shape of the tank, it's impossible to have the gauge read accurately at all fuel levels.

 

Well, for whatever reason, I was able to do it with a 5000$ Snap-On Solus scanner. I did a camshaft relearn with this scanner and that is what fixed my truck and stopped it from misfiring. The whole 200mi I put on my truck yesterday were all monitored by that scanner using freeze frame data. No more misfiring, I don't know if my retard is off or not. I was would think not because the truck is no longer misfiring.

 

The Solus is a great piece of diagnostic equipment, not top of the line, but a great piece nonetheless. I have a Solus 10.2, (along with other scan tools), and it will access the crankshaft position sensor relearn. It prompts you to bring the engine to 4000 RPM, and to take your foot off the throttle when the PCM takes over throttle control and performs the relearn. Is this what you did? If so, the crankshaft position sensor is now in sync with the crankshaft and supplying the PCM with correct data.

The Solus will also access camshaft retard and you should at least check it to make sure the camshaft position sensor is in sync with the camshaft. Camshaft retard can be off 15 degrees with no SES light, and no DTC's and you might not even notice a driveability issue, but it will affect fuel mileage. If it's off 15 to ~27 degrees you'd probably notice a problem. More than ~27 degrees and P1345 will set in memory and the SES light will come on.

 

I did a camshaft relearn, not a crank. The retard was off by 15, causing the misfiriing on cyl 1 and 4. since I did the Camshaft relearn I havent had a misfire, so im assuming that the retard is fixed

 

So you rotated the distributor until camshaft retard was zero, plus or minus 2 degrees?

edit: If you did not perform the crankshaft relearn, it needs to be done. Read post #50 again.

 

I did do the camshaft relearn, and the crankshaft sensor and data was fine. I did not do the retard. Since the misfiring is no longer happening, which was caused by the retard being off, cuz the sensor wasnt feeding the right data to it, its all fixed. since the sensor is working correectly, it therefore corrected the retard and the misfire.

 

I'm trying to figure out what you actually did to fix it. You said you did not adjust camshaft retard, and did not do the crankshaft position sensor relearn.

There is no such thing as camshaft relearn, period. Camshaft retard is an adjustment that you physically need to do. You can read the data on the scan tool, that's all. The scan tool does not adjust, reset or relearn it. The adjustment is done by rotating the distributor until camshaft retard on the scan tool reads zero degrees plus or minus 2 degrees.

As for crankshaft data: It is impossible to verify if the relearn data is correct or incorrect, or even what the data actually is for that matter. The only way to know if it's correct, is by performing the crankshaft position sensor relearn. The scan tool initiates that procedure, (as I described a couple of posts back). If you did not use the PCM from the Safari when you did the engine swap, the crankshaft position sensor sync data in your Blazer PCM is incorrect, guaranteed, and the crankshaft position sensor relearn needs to be done. If you did use the PCM from the Safari, (not sure it would work) it needs to be flashed to the Blazer for proper engine, transmission, speedometer, etc etc programing. That must be done with a TechII scan tool, the Solus is incapable of doing the flash.

 

I had a similar problem a year ago ran awesome well it should back then for 38000 miles but when i would do a cold start it would knock bang and clang and if i didnt rev the engine right away it would display a code on the dash if i started it and let it idle with the engine knocking banging and clagging the ses light would turn on in seconds with a po300 code took it to the dealer they couldn't figure it out had someone else look at it pointed me to the spark plugs and wires cleaned out the air intake and sensors no luck so i swapped out the cap with a AC Delco got the MSD wires and upgraded my coil pack to a MSD which i had to mod the original bracket to get it to fit directly which i didnt wanna mod my coil so i picked one up from the junk yard then i bought me some pulstar spark plugs gapped at .035 alittle pricey but i was furious with the po300 code i figured it was worth a shot still no luck it was still kickin out po300 codes so i had the old coil and ignition module laying around so i said the heck with it swapped out the ignition module and the problem was gone. So what im saying is test out your ignition module make sure its good cause mine wasnt and i myself threw alot of money in but for 38000 miles at the time i hope it pays off in the long run of the engine i also do remember having a heck of a time with the spark plugs i dont know how you installed yours but i installed mine without removing the wheel well dust shields and it was not fun but it saved me time and costed me aches for days in the long run however i was really careful but if i would have gotten impatient i know i would have cracked a plug from all the tight fit under the hood. Ive heard even spark plug wire rerouting can cause misfire problems has anyone else heard of that one?

Good luck to you man hope you get it figured out

 

my 99 mod 2wd w/190000 miles has tremendous issues in hmmid weather. a complete tune-up has been performed, including total fuel system flush. all is to standard, but as mentioned on heavy humid days, to say the least , conditions get ugly