I have a 95 blazer that suddenly started missing. I have spent the last 2 hour reading threads on this site and cannot see that anyone has had success in fixing s-10 engine misses. I was just driving along and it dropped a cylinder. can't even tell you which one. So I have replaced the cap/rotor/wires/ and plugs. Got 170 lbs on all cylinders. Whats next? I am stumped. I dont have a fuel pressure tester. I am headed out to change the fuel filter. Anyone got any suggests?

 

When I first read your title the image that popped into my head was of you going outside and finding that someone removed your engine! LOL

OK, more seriously, if you have an inductive timing light, you can check if there is current going to each spark plug by connecting the pick-up to each wire one by one.

I once discovered a short in the spark plug circuit due to arcing from one of the wires to the exhaust manifold which caused a lack of ignition in that cylinder. (This was not on a Blazer but the lesson is transferable.) However you said you replaced all the SP wires. Although unlikely, it is easy enough to check by running the engine and checking under the hood with the under-hood light off and in the dark.

Finally, if the coil is somehow damaged, it might cause a miss that can occur at any one cylinder. I once had a coil fail (again not on a Blazer) in a way that the step up in voltage was insufficient to cause a spark to jump the spark-plug gap when I was accelerating hard and when the cylinder pressures were increased. When cruising it worked fine.

Good Luck

 

actually, last week I took a spark pug checker and tested all cylinders and they all seem to be firing, but who know if this Chinese tester work good.

 

I wonder if the amount of spark (more technically the actual voltage at the spark plug gap) could be the issue rather than if there was a spark.

If you knew if the miss was at only one cylinder that could help.

Oh, here's a new thought: Perhaps one of the injectors has failed? If so then that would explain why one cylinder would not be firing. Would evidence of this show up by the condition of the spark plug?

 

There are some things that you can do without fancy tools.

You must have a strong blue spark that can jump a 1" gap. First test the coil output then each individual cylinder. Use either a spark gap tester with a ground clip or you can use a grounded probe by pulling off the plug wires. That takes a little skill so that you dont get bit or fry your module. If you need more direction here let me know.

Related to the abvove you can do a drop cylinder test. You pull and ground each plug wire while the truck is running to see if you have a cylinder where you do not lose RPM.

Do you have access to a code reader? If so, any codes? What are your short and long term fuel trims?

You can do a spray water bottle test to check for vacuum leaks. Let me know if you want guidance on this.

The check for injector output in the post above needs a fuel pressure gauge and pulse tester (not too expensive), in the even that you have access to these tools.

Theres plenty more, let me know.

George

 

I had a crazy missing all of a sudden on my 96... turned out to be the whole distributor assembly that needed replacing.

 

It's the distributor if you have good spark at the coil output and bad output at the distributor tower posts. If that's not your situation then don't replace your distributor and continue looking for the problem. I have 203,000 miles on my original distributor so they are capable of lasting a long time. It's OK to swap parts first if you are going to do those anyhow because they are known problems or due for maintenance. Sometimes you get lucky. After you freshen up anything in need of some love, it's back to diagnosis to target your time and money on the problem.

George