Hey guys new to here but I am wondering if anyone can offer some advice. I have a 98 Blazer with about 235,000 miles on it and I am having a problem when accelerating. It seems to stumble for me between about 1800-2500 RPM and low throttle positions. If I open the throttle it runs fine.

From what I have found is that it seems to be the worst on cold starts when the humidity is high or after a rain and the temperature is about 50-70 degrees. This leads me to think a spark problem but the plugs, wires, cap and rotor were all new about 20,000 miles ago. Also if it were a spark problem wouldn't it be worse under higher throttle positions.

Let me know what you guys think. Where is a good place to start?

Thanks,
Tim

 

I had that same exact issue as it clears up after its been ran a while.

As its moisture affected then I would check under distributor cap and rotor for corrosion caused by the damp air. I live in southern louisiana and it gets pretty damp here.

What I did was replace the distributor cap with one that had brass contacts. That seemed to fix the issue for me.

I was also told that there are screens on the distributor to keep the moisture from collecting under the cap. I never found them and quit looking after I fixed the symptom.

Alternatively if the wires have a break in them and are arcing under damp conditions, a good way to test that is to park it somewhere dark and "mist" the wires while the motor is running. If you see sparks, change the wires.

 

ok Thanks I will look under the cap and maybe try spaying a little WD-40 to see if that helps at all. Do you know where you got the new one with brass contacts.

Also did yours only act up with low throttle position then when you gave it more throttle did it run fine?

 

Didn't matter to me. It only happened at a certain rpm range underload. I got mine from advance auto but I'm sure you can get them at other places...just make sure and pull it out of the box to see if it has brass contacts.