I will try to make this as brief and concise as possible. I have been experiencing power loss at varied times and with no real discernable pattern. It occurs sporadically when the vehicle is cool or at least sitting for a couple of hours. When accelerating from a stop, there will briefly be no indication that my blazer wants to accelerate until I really get on the accelerator and once you get the rpm's up, it will smooth out and run fine. This may happen once a week during which I may start the Blazer 10 - 15 times, or it may go 3 or 4 weeks and not happen at all. Last week I drove to a restaurant in the rain for dinner and the blazer ran fine. Shut it off and had dinner, about and hour and came back out. It had continued to rain and the power loss was back and wouldn't go away. I drove about 20 miles and had to fight the vehicle to get it home. Let it set at the house for 5 days until I could get some time to work on it further. Pulled it in the garage this weekend and broke out all my scanners and diag tools and it was running perfectly. I have driven it to work the last two days, about 35 miles each way, and it hasn't missed a beat. It has shown no codes.
I have recently replaced the dist, rotor, wires and plugs. I dropped the tank and replaced the fuel pump and have also replace the fuel filter. I have since checked all the fuel pressures and bleed down rates and have found them to be within spec as has been posted in this forum.
I have an endoscope that I will be using to see if the spider has been updated, but I don't really believe that this could be causing this issue. I haven't found anything through the search function that sounds very similar to my symptoms.
I would greatly appreciate any help or ideas that anyone might have to offer.

Thanks for you time.

Richard

 

Could be a lot of things. Kind of sounds like flooding clearing out when RPMs go up. On the other hand could be spark jumping elsewhere inside distributor cap. Strange that a misfire would not set a misfire code on a 20 mile trip of misfires. Maybe something is preventing the misfire detection from working. Going to be a tough one.

You can check cam sensor retard value
You can replace distributor cap
You can check TSB#: 03-06-04-041A
You can induce a miss and see if PCM can detect it.
You can monitor various things with scanner when problem actually occurs
Of course this is not a complete list of what can be done - just some ideas.

Good luck

 

Thanks for the ideas, I will give some of them a try and let you know if I find anything that appears to be the cause.
I also apologize for leaving out some critical information. My Blazer is a 1998 4wd LT.

Thanks again!

Richard

 

Howdy!

Have you checked the PCV system, specifically the elbow connecting the PCV hose assembly to the PCV valve cover (on plenum). Mine recently gave out resulting in a number of symptoms, including random hesitation/surging on acceleration similar to what you describe. Here's a link to a post I made about it: https://blazerforum.com/forum/2nd-ge...olution-90048/. Was a cheap and easy fix, also have slightly better fuel economy now.

 

Check all your plug wirers again the one from the coil to the cap also.
After dark with a mist/spray bottle mist some water around all wires and cap. You might get lucky and see a spark someplace.
no 300 codes is odd.