I have a friendly relationship with a shop that repairs vehicles both from my family and our business. I am in the process of buying a 95 blazer from an uncle. I dropped it off at this shop telling them "no big hurry, check it out when you can". Six weeks later it's a bit of a running joke. They know I don't really need it and they are stumped on a misfiring cylinder. Now I pop my head in the door and yell "hey fix my car" for a laugh. Anyway I thought of a fun Idea. How about a shop pool board on the misfire cause. My quest in this forum is to generate an exhaustive list of potential causes, create a board for the shop and they can put their money on their best guesses. If no guesses right I keep the money. 😀

 

compression check on bad cylinder .... had a rondevous lose a rocker on that cylinder

 

For a few month ago I got a 99' T-10 Blazer pretty much stock.
And me WHO has reacently has had' a 99 T-10 and never before discovered' this Wierd problem.


What the car does: When the engine is cold or hot it make those like you turn of your engine when your are driving, small to big bumps or like you pull tour handbrake when your driving. It just go out and start again.


I got a few ideas about what it could be, but i'm not sure.
The fuel-filter ? The fuel-pump ? The ignition cables ? 1 or more of the spark plugs ? Or something that i maybe not know off or think about.


It don't do it each day, it just come and go.

 

So far the pool choices are...


Electrical
Coil
Plug
Ignition cable
Distributor
Timing

Lean Mix (My guess since I only noticed the misfire at idle)
Stuck EGR
Leaking intake gasket (they spotted this and fixed but problem remains)
Mass Air Flow Sensor
Fuel Pump
Fuel Filter

Mechanical Stuff
Compression (I know they've checked that already but they could have checked wrong)
valves
camshaft
leaking head gasket
damaged or broken rocker arms
defective fuel injectors (and/or the electronics that control them)
slipped or incorrectly-installed timing chain.

 

Put on acdelco cap and rotor and ac delco wires. could also be a worn dist. gear. If cap rotor and wires help ,then leave it as is. Especially if it has miles on it. chalk it up to age. 90% it electrical

 

Got a little laugh out of the misfire pool chart. They are going to give it another look in a couple days. Owner of the shop is leaning toward mechanical issue, they replaced egr, fixed an intake leak and say it appears to be getting all else it needs to fire but isn't. Not sure if AC Delco wires and distributor are on it. Barely peeked under the hood before I dropped it off.
I'm wondering if my uncle may have driven it a while misfiring due to the intake leak and caused some other damage that now is the cause. Like catalytic converter?

 

You have injectors but it's a junk injector assembly. That's next on the list for my '95.

 

Check to see if the timing chain has stretched

 

The mechanic used a camera and saw that an injector is not spraying. He sees what he called good voltage at the injector and for a while thought it would be the ground wire, but no. Then he put a different spider injector on it he had from an engine replacement where he didn't use the one that came with it. same problem.

 

Most recent attempt: The injector was spraying intermittently on cylinder 3. (ignition disconnected spraying into rag) So with everything else tested and a different spider tried, they thought it must be the pcm and tried a used one on it. Still does it.