# 1 cyclinder misfire!!!!!!!!!!!!!!!

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.

I do like to start from itch, not scratch. This engine runs rough? Coil. Computer AND chip? Coils are not always bad all the time, sometimes just some of the time. Computers are a real pain. Checking a distributor is not the same as installing a new one??

Any dealership that hasnt changed either the whole coil or tried changing the whole computer, or changed the whole distributor is not worth going back to. Taking an engine apart before doing any of this is beyond reproach. Dealers are more than capable of simple things such as this and should not depend entirely on their huge amount of gadgets to "read" things. "Readings" are a temporary measure that only takes into the account the conditions of the vehicle at the very time the readings are take.

May I ask the type of injection and spark system on yours? I am not aware of all more modern systems in use. I am aware of how they allwork, just not where they are used and on what years.

all i can tell you is its a 4.3 v6 votex with fuel injection and stock electronic ignition. I spoke with the dealer again today. they said that a while back the had some chevy 350 's come in with similar problems, misfiring one cyclinder with good compression, but had a bent valve. at this point they want to go and remove the valve cover and check the spings and rockers. At a starting price of about $225.00 i'll do it myself. The only problem with this is i cant tell if anything is wrong with the valves unless i go deeper. Any Suggestions?

A bent valve WILL NOT seat! Plain and simple. Man I don't know what to tell you other than what I have already said. I would get a second opinion on it and see what a fresh set of eyes will suggest.

i'm going to make an attept to pick it up wednesday and check a few things on my own. If i have no luck ill problably get a second opinion and not even tell the other guy what the history is so that hell be able to look at it with a fresh set of eyes like you sugessted. ill stay in touch.

you guys are going to love this one. after picking it up from the shop i took it to another chevy dealer and ask them to tell me what was wrong with my blazer and i told them nothing of what had been done prior to this so that they could go into it with a fresh set of eyes. well, they looked at it for 2 hours and said it had a vacum leak on the lower intake at the number one cyclinder. he said they sprayed starting fluid in the area and watched the the misfire go away. after the starting fluid went away the miss came back. he then gave me a print out and i told him that that gasket had just been replaced by another dealer and i would take it back to them to replace it. Well after i took it back to them they said they ran the same test and it didnt effect it , so they replaced it anyway called me back today saying that it is still missing. and what i dont under stand is that these are the guys that said it was in the valves why didnt they check them ehy they were in there?????? i would have been more than glad to pay for the repair if thats what it was. now i have had it to every dealer in the world and no one can fix it. now im more lost than ever.

A leak in the lower intake? Did he offer to check the intake and replace if need be? Cracked perhaps and not a gasket? Just guessing. If the intake were removed and I was checking for a miss, I would certainly have measured the lobes on the cam. Just commenting. I mean if I were thinking bent valve such as was recently suggested, then the lobe wearing funny could easily be checked with the intake removed.

What was the result of a leak-down test? If we were looking for a vacuum leak? Anyone do anything about a substitution of a coil or distributor?

Has anyone looked under that valve cover while replacing the intake gaskets? I mean a piece of valve spring laying in the wrong place will be more obvious only to those who look. Had one go that was brand new one time and it was the INNER spring of double springs. Hard to see but interesting result. Under that same valve cover a bent push rod is another one not that easy to see. Did we decide yet WHICH cylinder is the problem? Knowing that would help a bit.

all the test you speak of have been tried, so they say, and i asked why they didnt check while they were in there, and they tried blowing smoke up my A##. at this point im going to go pick it up and drive it till it falls apart and trade it in on a NISSAN, ive always bought chevys my whole life and consider myself a diehard chevy man but after being crapped on by 3 different dealers and calling chevy corporate and getting no help, i have no choice but to go with a car company that i feel will provide better service and a better product.

My question to you is if it isn't under some kind of warranty, why were you taking it to a dealership?

Anyway, good luck with whatever you do. All automakers have their problems, don't think that going with a new one to you that you will be rid of things that break.

To be speaking my mind? No reputable shop and the dealers are that, would ever do things the way I am being told they have been done. It would be a strange customer indeed that would hear a dealer tell him that the intake was leaking and then NOT let them fix it. Instead choosing to have another "dealer" work on it that has failed to fix the problem before. No reputable shop would simply test and not substitute a new coil/distributor in cases like this. No matter what the machines tell them, they know better. I know better. To never replace the main computer?? After all the problems they have had? No reputable mechanic would have guts to start taking the whole thing apart before checking all of that, compression, leak down and then NOT measure lobe lift, look for bent pushrods, broken valve springs, etc., when this all is relatively easy once the valve covers and the intake is off. etc, etc.

I am having a really hard time getting all this down, but if these posts are real, then the customer has all the information he needs to make a dash to the GM hotline. I would have dialed them up long ago myself. Get yourself a loaner while they find this problem. Even if it was not under warrenty, they now owe you a fix.

quote:

ORIGINAL: swartlkk

All automakers have their problems, don't think that going with a new one to you that you will be rid of things that break.

Wythel,

It is not the brand of car but the quality of service you need. My mother had purchased new in 1989 a Nissan Maxima, they had it for a long time when the tranny started to make noise while still under warranty the dealer fixed the problem but they did a sloppy job of it and messed up a seal for the tranny cooler lines. It started to leak and they contended that the repair would require her to completely rebuild the tranny. Well her being the person she is tried to get them to fix it since they were the last ones to touch that part of the car. The dealer refused, she had the care towed to another shop and they fixed the seals and the car is still running in the family.

So it does not matter whether you have Ford/Chevy/Dodge or any other brand they will all have their specific problems, what you need to find is a manufacturer's service department that you feel is trustworthy and go from there.

Good Luck

P.S.

Buy yourself a can of starting fluid and see if the manifold is the problem, #1 Cylinder is the front of the engine drivers side. You may have a warped intake or head in that area...

well i picked it up from the shop and headed home and noticed the idle is set a bit high, jerking when i put it in drive, then i noticed that as soon as i started driving that it shifted all gears prematurely and once i was going the passing gear wouldnt work. timing?? and what is it set at?

I'd take it back to the shop & do a drive with the tech to show the new problems.....

it was a idle/ shift switch.

well guys , i finally said forget it for now and brought it home, 2 dealers said they didnt know what it could be and the third says that they think it is a problem with the valve on the number on cyclinder. remember now the compression is fine on that cyclinder but they said that they have checked every coponent on the engine and used test parts to replace original with and have finally eliminated everything else. i do have a cyclinder 1 misfire alarm. i guess ill remove the valve cover and look for a problem with the spings etc. has anyone ever heard of a valve sticking, bent, or malfunctioning but still have good compressioin????? (not me)

Yes, a double spring valve can give good readings due to one (outer) spring still working, even if inner is broken. I dont suggest this is your problem, but it has happened to me. Misfire on mine only happened above a certain (perhaps 2500 or so) rpm. I guess it would also depend on how much of that spring had broken off. Mine had little over one coil gone and thus was big enough to actually stay put and not injure the rest of the motor. This may have also been the reason for mine only missing at irregular intervals at a higher rpm. If I had to guess, the piece bouncing around in there moved around, causing intermittent noise problems with the LARGE spring. If I had not heard it, I would not have believed it. These are very severe duty parts and not intended to break at 9000 rpm, if you know what I mean. I have used these springs before and have seen everything around them wither away while they kept on working. Couldnt believe a brand new one doing this. I had several mechanics try to figure out my problem while it was there and no one came up with the valve spring problem. I saw it by luck when I jerked the cover looking for that tick now and then.