Okay, to keep the topic legal, lets say this problem relate to my big heavy ummmm, camaro classic. (Certainly not to my caprice daily driver). Okay, I have a low mileage 1991 the L03. On the way home the other day I got the check engine light. I pulled a code 45 when I checked (rich condition detected). I did some digging and noticed it was smoking when the engine was reved (to pass or whatever) Reved it in the driveway and got smoke and black crud on the driveway from out of the tailpipe. I pulled the plugs and the number 1 was black and cruddy, the rest were good. I replaced them and after cranking and reving again, number 1 became black again. The rest still good. I had recently done the valve seals and thought maybe I got a bad one, so I replaced the #1 intake and exhaust. Just to test, I used the positive retention style viton seal on the exhaust too instead of the umbrella seal. No change. Took the plug back out and checked compression. Read right at 150 and didn't seem to bleed away quickly. Didn't check the other cylinders as it started to rain and it looked like #1 was the problem anyway. Do you think it could be a worn valve guide? I am thinking that and I have also heard of intake manifold gaskets, but primarly I hear of those on the LT1/L99's, not so much on the L)3/L05's. Also it's the #1 cylinder, not one of the rear ones. The car seems to run o.k. The smoke looks grey, even black at a couple of times, which points to fuel rather than oil, but the plug was quite black. Also I have noticed increased oil consumption, but I attributed that to a leak at the oil cooler adapter and a strange leak at the oil filler cap (swapped PCV, but it's still there) that seems to have gotten worse. I could be wrong though. Oh yeay, no oil in the coolant or anything and like I said, it runs good, no strange noises. Any ideas here? If it's any issue that'll require any work on the heads I'll probably go to the vortecs. But hopefully it's an easy fix. If not I may be looking at the "4 inch bore mod" as I don't really want to dump a lot of money into the 305 with GM 350 crate motors well under 2 grand. But I find it hard to believe it would be something serious on a sub 50,000 mile motor. Anyone got any ideas.

 

Sounds like your getting the rich code because of the unburnt fuel being dumped out of the number 1 cylinder. What do the other cylinders pump up to? 150 sounds a little low for a 9to1 motor, but about right for a 8to1 motor. Do you hear any kind of air noise out the intake or exhaust when you put air to the cylinder? You can test this by taking the check valve out of your compression tester and just hooking up your air hose. Listen for air out the intake, exhaust or worse through the breather. That should let you know where the leak is going. This is all assuming your actually loosing compression some where. If the compression is close to the other cylinders it might be a spark issue. Either bad wires, cap, rotor. Something to cause the one cylinder to go dead.

 

Looks like one of the valve guides on the number 1. I put a vacuum gauge on the pwr brake vac. port and the needle vibrated like crazy between 22 and 19ish. I figure its a faulty number one because thats the oily plug and it only has 45k miles on it so I don't think they are all bad. I'll probably just replace the head on the drivers side as they seem cheap.

 

I'v never heard of just on guide going out. They usually all wear out at once, and with 45K I'd suspect something else is amis. Did you perform a cranking compression check on the No.1 cylinder and the rest to compare. This kinda sounds like when my brother broke a ring land, the one cylinder cranked ok would burn oil in the dead cylinder. The ring still sealed even though over 1/4 of the ring land had been blown to bits.

 

Prolly a piston ring. Don't think an LO3 can have much single cylinder fuel problems other than that delivered by the factory (TBI can't fail in such a way to cause 1 cylinder problems, at least not that I'm aware of).
If it happens in such a short time, I doubt it's a valve. The oil has coated your O2 sensor and makes it read 0 oxygen, which is rich, which has set your code.
Only other thing that I can think of is an intake manifold gasket leak into the oil vally, but your oil problem seems a bit more serious if it coated it well, after new plugs and just starting and revving.

 

check your timing and distributor. when my dist. went bad the car ran very rich. my dist only had 2years on it when it went bad... this is a part that is normally over looked when problems arrive...

 

I'm thinking the same thing. It would explain everything perfectly...

 

Ring?! What would cause one ring to fail? I was thinking this at first but the vacuum gauge looked like valve guide(s) in that it was pulsating between 19 and 22 psi. Ill do a comp check on the #2 to compare it to the #1. I wonder if it might not be intake manifold related as I removed the two bolts right there by the #1 to get the engine hoist hook off to remove the valve cover when I did the valve stem seals. Just a thought. I'm getting desperate. When you guys talk about rings, that's worrysome.

 

If I were you, I'd redo the intake manifold gaskets, just in case that's it, before you tear it all apart (read my earlier post, where I said it could be that).

 

Okay, just went out and drove around to warm it up. Upon my return I did a compression test on the #1 and the #2. #1 (the oily plug) was 155 PSI. #2 was 180 PSI. Keep in mind it's a 40,000 mile motor so 25 PSI seems kind of high to me. Am I correct to assume this is not normal and to say you guys are probably right and that I have a bad ring on the #1? man, 40,000 miles and I'm gonna have to tear it down? What the heck?

 

Oh yeah, I shot some oil into the #1 and it jumped 30 PSI to like 190. Ring?

 

Bingo.

 

that sucks, but it's more common than you might think. The stock low compression dished pistons are really thin around the top ring land, actually they start out thick, but then they neck down right where the ring land stops, so there is a nasty stress riser there, they usually just pop the top ring land off right around there. You didn't happen to find that particular plug with the end gap pushed shut did you? My brother toasted 3 cylinders runnng too much compression with too much timing and 87 octane (moron, it really doesn't take that long to check your timing). All 3 cylinders ended up with the plug ground strap pushed shut, but with no aparent impact mark, he replaced them and ran the motor like that for 2 weeks before tearing it down. Funny thing was we never found any piston chunks, they all went out the exhaust with no damage to anything but the plugs, my guess is that the chunks were in a semi-molten form and weren't hard enough to hurt cast iron, but still hard enough to push the ground strap shut.

 

My question is what kind of driving did this to the ring? Surely it wasn't random, right?

 

In my brothers case he was running a mechanical dissy and carb, with absolutly no tuning what so ever, combined with cheap gas. Basically he went stupid, I kicked his but, so it's ok now. He got into major detonation and couldn't hear it over the exhaust leak he had.

Just to clarify the ring it's self probably isn't broken, it's probably the ring land that support the ring that breaks. The ring still tries to seal, but can't because it's flexing all over the place without the top half of the ring land.

In kirkm's case it could of been anything. The local gas company around here ran alot of chevy's in the 90's and they had major problems with the knock sensor going deaf. Since these trucks were loaded down all the time they relied on the sensor to retard timing so the motor chewed up pistons pretty fast. They ended up replacing the knock sensor every 30,000 miles, and this fixed the problem. Don't know why they had so much problems with the knock sensor, might have had somthing to do with them beating on these trucks off road all the time.

 

Yeah, the car has had a very easy life. No agressive driving. When I got it, the timing was 6 degrees retarded, but I didn't think that would kill it. Anyhow, crap happens. I'm going with a reman L05. I'm getting a chip that'll let me keep the L03 injectors while it's stock (probably a year or two at least) to save a little cash. So all I need is the knock sensor and the spark control module.

 

That should do it, sorry bout your luck

 

Make sure you still take the LO3 apart so we can see who got it right!

 

This don't make any sense. I won't argue the motor may have a bad ring on #1 but that is only going to cause blue smoke and oil consumption problems. That will not cause it to blow black smoke and set a code 45. Granted if the o2 was getting coated in oil it could cause the computer to miss read the o2 and make it run weird. But you should be able to disconnect the o2 put it in open loop and drive the car just fine with no black smoke. Personally I think you are putting in an engine that is not needed and have a completly different problem. Thats just my 2 cents though.

 

cranking compression is low, so somthing is up. Either there is a ring not sealing or a valve not sealing, either way it's gotta come apart to find the problem. Some times oil smoke looks a bit grey when viewed out the back window in small quanities.

 

And it's difficult to overfuel just one cylinder on a TBI car. The code 45 being a rich condition detected means the ecu actually leaned out the mixture to it's limits, but the O2 kept reading rich (falsely). I'm not sure what the ecu defaults to on code 45 on a TBI, it may just keep trying to get it to switch by staying lean, or it may reset block learn and integrator to 128 and go open loop.

 

Broken Ring land on the #1. I am ironing out the L05 swap now.

 

Ok who owes me money? Man that sucks you had to tear it down, but for some reason that always seems to be the case. If I ever get any time I might saw a piston in half to show how thin the casting is in that area. All it takes is a wee bit of detonation or a crappy casting and bad things happen.

 

I believe the rich condition came as a result of the plug becoming fouled by the oil and the cylinder dieing. There was much oil in the exhaust though...towards the end I could rev it and I'd get a little oil slick out the tailpipe.

 

Just lie to everyone and say the car was originally designed to James Bond but you got ahold of it instead

 

Yeah, I had the rare "007" option...It included an oil slick and a smokescreen all activated by the accelerator pedal. Now it has the "4 inch bore mod"