I've posted a couple of times about my 94 blazer with the vortec engine. There's always something wrong with it and I can never figure it out. It's a long story but this problem started with the oxygen sensor going. We replaced that and had the egr cleaned out. Since then it still hasn't been quite right and my boyfriend and I can't figure it out for the life of us. For a while it seemed like it was missing a lot in first gear but would go away in higher gears. It also surges a lot when coming to a stop and idling rough. So on a hunch I thought we should change the spark plugs. All of the plugs on the passenger side looked like they had some sort of buildup on them and they were white with ash. After changing the plugs the missing stopped but the other problems continued. I was satisfied enough. The truck didn't miss at all for a good two weeks but now every once in a while it does it once or twice. Then today I turned the truck on and had been sitting with it running for almost a minute. I switched the heat from off to vent and then it surged, the dash lights went dim and then bright again, and then it just stalled out right there. It started right up again and I tried to recreate what happened but it wouldn't do it again.

I'm out of ideas because we have fixed and replaced so many things on this truck including, recent fuel filter, spider injectors, entire distributor, heater core, battery, alternator, plugs and wires, o2 sensor, egr cleaning, brand new exhaust and catalytic converter.

Some people think it's a lemon but I just think it's hit the point where everything is wearing out and needs replacing. I mean it has 155k on it with 25k put on in the last year.

Either way, I'm all out of ideas and was hoping someone out there would have some ideas or may have had something similar happen to them before.

Thanks! and sorry for writing a book. I've looked at other threads but not found anything unique to my problem.

 

Sounds as though you have some vacuum leaks somewhere.

Have you run a fuel pressure test, paying particular attention to the pressure leak down after the pump shuts off?

Here is a little ditty on ash like coating on spark plugs:
Based on that, one other idea I would like to throw out is blocked oil return galleys under the passenger side valve cover. This will lead to excessive oil leaking by the valve stems and into the cylinders.

 

I didn't realize that fuel additives would cause that. Wow. We've been putting in the Lucas tune up in a bottle because we figured it would help the truck run better. So does that mean I'm better off without it? I don't put it in too often though so that surprises me a little. Also, I'm still learning about cars so I'm not sure how to do a fuel pressure test. I'm also not sure how to check for a vacuum leak. Can you possibly clarify about the oil return galleys and how I would check for that too? I check the oil level pretty often and I don't notice the level going down very much. The oil pressure stays around 40 while I'm driving. Sorry for being a noob. I'm just glad that this blazer has helped me learn so much more about cars.

 

Its gonna be hard to explain all that . I would get a Haynes manual and check the items posted previously. The Haynes manual will explain you questions with step by step instructions

 

Thanks. I have a Chilton manual. Will that do for now?

 

Chiltons & Haynes are equivalents. It should do ok for now.

Concerning the valve seals and possible problems with the oil drain back holes, you would have to remove the valve cover on that side of the engine to check either. You could get the valve seals replaced on that side as well.

You could tell if it were the seals really quick with a bore scope, but not everyone has one of those! More plumbers have them than mechanics!

 

My dad probably has a bore scope. He's a mechanic with more tools than he knows what to do with. I usually just ask him car related questions but I'm up at school and I'm trying to learn as much as possible from more than one source.
Unfortunately just now I noticed a new development. The truck is ticking. Not sure what kind of tick or where it's coming from but it's not too loud and you can hear it better on the passenger side of the truck. I also can't hear it unless I'm not in the truck. So I'm worried that now I'm pretty much screwed...

 

A tick or a knock? Can you hear it get faster if you hold the door open and rev the engine?
Could be as simple as a stuck lifter or and exhaust doughnut

 

I'm not positive on the difference between a tick and a knock but I had another car that definitely knocked and it sounded like dragging a stick across a fence. This not a very loud noise and only really heard on the passenger side. I think it gets faster as you rev the engine but it doesn't get louder.

 

that could be something in the head, you will know what a knock is, sounds like someone is hitting the motor with a hammer lol try putting a can of restore in the oil idk if it will help but its worth a try