Over the last 3 months my 2001 blazer 4.3 has been to 3 different dealers and goodyear. I have slightly over 100,000 miles and have maintained this blazer very well. Ill start off telling you what it started doing then what has been replaced. originally check engine with bank one censor, multiple cyclinder misfire, # one cyclinder misfire, running too lean and more. I started out with new plugs, wires ,dist cap and rotor, fuel inj. spider, O2 censor (oroginal part from dealer, not a bosch), fuel filter, and in the mist of all this i had a to have both intake gaskets replaced, oil & filter with radiator flush. We have at this point only one alarm coming on regularly. number one cyclinder misfire. we rechecked all spark plugs and wires, egr valve compression , replaced O2 censor, again, checked cat coverter, fuel pressure regulator, ran fuel press checks and many many more tests but still the dealer is scratching his head. Is there anyone out there that can pull this rabbit of of my hat!!!!!!! what is wrong with this truck from hell?

 

pick-up coil??? or maybe ignition module??

 

I knoew someone that had the same proble and even bought a new engine and all it was was a fualty spark plug. I would change the plugs agian and what red blaze said. You check the compression right?

 

I have also heard of a cracked distributor housing that causes the advance to get screwed up. This would cause a miss at higher rpm when the timing would be off.

You can never over look the fact that all components, no matter how well they are manufactured, have a defect rate. So it is possible that you got yourself a bad wire, plug, cap, and/or rotor. I would pull everything and check them all.

 

I went to the dealer today and he said that he changed out all the plugs, wires, coils and mores. He said he is at the point that he is thinking it may be internal. He said that he had checked compression many times and it was good but he has no other ideas. If compression is good, why are we looking into the head? Hes not charging me if this doesnt fix it but dang man, i need some help here.

 

A messed up egr will make your vehicle missfire and stall.

 

its been checked,,thanks anyway.

 

Ok, well, I got an email saying that wythel had replied saying that the egr valve had been checked, but it isn't showing up for some reason.

Don't overlook the distributor itself. If they are ready to pull off the head, grab the keys and GET OUT OF THERE!!!

If the compression checked out ok, then there isn't a problem in the head. Not to mention that if they are a good dealership, they'll have a bore scope where they can look at everything through the spark plug hole. That's not to say that you might not have a bad lifter or a warn cam lobe either. Both of which could cause the cylinder to not see the proper air/fuel and *could* cause your misfire code. Those are extremes though... Well, not so much an extreme for a collapsed lifter, but they should be able to check that by removing the valve covers, NOT the heads! To replace it, they would have to remove the intake, but again, not the heads. If anything was wrong head side, you wouldn't get good compression. Things that could be wrong head side that *could* cause this same thing would be a worn valve, a bad valve oil seal, bad compression ring or oil ring. All but the valve seal and oil ring would cause a loss of compression which is not present. The bad valve oil seal or oil ring normally causes the plug to be oil fouled. If you didn't see that on the plugs when pulled, then you should see it on the new plugs given that you haven't fixed the problem.

So in summary, don't let them pull the heads cause they have already said that the compression is good. Nothing head side should be causing your problems. With that said, it is either still ignition related or air/fuel related. The air fuel could be caused by a number of things, 2 of which are a collapsed lifter or a worn cam lobe, either intake or exhaust for both.

Good luck and keep us informed.

 

i was told that the distributor was checked and didnt make any difference. and yes the have a scope but i havent asked why they dont choose to try this instead, maybe they cant see everything as well, i dont know. i was tol that tghey would work on it today trying to find the problem. if they cant resolve this today they will call before going into the engine. what would you guys advise at this point?

 

I don't actually think you can check for a collapsed lifter without oil pressure to the lifters. It would be easy enough to check for a worn cam lobe by just comparing the lift with that of another cylinder.

I have also done some reading and on some other GM vehicles where they were getting false cylinder misfires, there was a PCM update to correct for the problem. I haven't heard of this from any 4.3L equiped vehicles, but just thought I'd bring it up.