okay, well I just poured it down the throttle body, might have gotten a little more than a quarter in once it stalled out, but it wasn't too bad. I'm gonna let it sit for 30 minutes like you said, and by then it'll probably not even affect it's start up or hydrolock it, hopefully.

 

I would have just put a piece of tape over the light.

I rooting for you though. Hopefully this will help out with your problem.

 

I have never hydro locked a motor with Seafoam in the 20+ times I have used it and I have dumped a bunch in towards the end. As with anything, there's always a first time though... As the engine sits though, any excess will work its way past the rings and into the crank case so you shouldn't ever have any problems with it locking up after it has sat.

 

All right, so I drove the **** out of it on the freeway. Took about a good 5 miles for the smoking to stop once I started the truck. Floored it getting on the on ramp and I cruised once I saw the light flashing. I did that for a good half tank. I alternated, just slowly getting up to about 65+ MPH, and other times I just floored it and went up to about 95MPH.

Now, I am assuming that this wouldn't be an instantaneous fix, right? I gotta drive it around like this for a while and hopefully it will improve with the mileage that I put on it.

I could noticeably tell that I had a smoother idle, so at least I got some positive improvement with that. Baby steps.

 

Good to hear! Keep us updated!

 

Okay, so I got access to a scanner today. It was weird though, as I was driving to my old shop, the light came on for misfire while in the city and it has never done that before. So I hooked it up and now on top of 3 and 6 still misfiring, 1 is now a regular misfire as well, but no where near as much as the other two.

In one cycle:

Cylinder 3 had 296 misfires
Cylinder 6 had 288 misfires
Cylinder 1 had 12 misfires

My Blazer was driving pretty good for about a day after the seafoam, but now it's just about where it was before, so I guess that didn't work out as well as I would have hoped. So, what are my options now? Go to a dealer and get the CASE relearn done and go from there?

 

I am starting to wonder if there isn't a problem with the cam... Like a wiped intake or exhaust valve on those two cylinders that is not fully opening the valves.

 

That thought has been lingering in the back of my mind for a while now. I am hoping that it doesn't come to that.

 

Wow, after about 2 hours of reading this, doing research and some note taking i have a few questions and maybe a few ideas. Now in one of your replies you said that you bought a new ICM? Did it make any difference? and you said that the crank sensor check out ok, voltage wise and resistance wise but did you check the reluctor wheel on the crank for damage/missing teeth? if I were to throw a few guesses at it one of the things I would suspect is a slightly loose timing chain or even possibly a bad PCM, I say this because the PCM controls spark timing, air fuel metering egr, IAC and so on. i would try to find someone with the same year/engine and swap PCM's to see what happens, and I didn’t see anything about a vacuum reading either. With these 4.3's I have heard of aftermarket dist. caps causing cylinder misfire. And this is going to sound dumb but are you sure that the firing order is correct? Maybe if cyl 3 and 6 are companion cylinders they could have gotten swapped somehow?

also found this on shopkey for your same problem: cyl 3 and 6 misfire with p0300 and flashing ses -

Using scan tool, check parameter- CMP RETARD. Should be 0 degrees, plus or minus 3 degrees. Also check the distributor drive gear for apple coring- drive gear from factory installation not hardened properly. Will cause phantom misfires in all V6, V8 small block, and V8 big block engines. Tip to get cmp retard to zero degrees is to modify distributor hold down clamp, so that the distributor can rotate for adjustment. All 4.3 engines, code L35, (W), and LF9, (X), 1996 to 2006, need hold down clamp modifications for correct cmp sensor/retard reading, during removal and installation when replacing intake gaskets, and/or distributor drive gear replacement. From the factory all V6 4.3 engines are at -7 to -9 degrees, brand new vehicles, on the lot.

really hope this helps! but if it were me i would have replaced the engine/pcm by now :P

 

ICM made no difference. I checked for both things for the crank sensor and it was good. When I hooked it up to the scan tool, the CMP was at 0 degrees. Haha, yeah the wires are correct. Hard to screw it up considering they are on different banks

I read about the drive gear somewhere and it was similar to that, but considering I got a new distributor, that kind of rules it out. My vacuum was fine. Didn't have any vacuum leaks either. Changed out all the gaskets just to make sure.

A bad PCM has come up in my brainstorming, but I am hoping it's not. Never even thought of the loose timing chain. Would that cause a misfire similar to that? I would think it would affect all cylinders, wouldn't it? At any rate, it wouldn't hurt to check it out, right?

Never checked a timing chain before though, just timing belts. What would I look for when inspecting it?