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General E46 Forum
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Old 05-10-2015, 12:49 PM   #21
jdstrickland
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Before you go after the valve cover gasket, you should make sure that there are no broken hoses or ducts leading to the intake. Broken hoses/ducts is the #1 cause of the problem you have, by a very wide margin. The other things that come up are usually flukes.

A leaking valve cover gasket is far more likely to present as a mess on the garage floor or the smell of burning oil than it is to be seen as codes for a lean condition.
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Old 05-10-2015, 12:55 PM   #22
traxnox
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Originally Posted by jdstrickland View Post
Before you go after the valve cover gasket, you should make sure that there are no broken hoses or ducts leading to the intake. Broken hoses/ducts is the #1 cause of the problem you have, by a very wide margin. The other things that come up are usually flukes.

A leaking valve cover gasket is far more likely to present as a mess on the garage floor or the smell of burning oil than it is to be seen as codes for a lean condition.
Oh no, its definitely the valve cover gasket. We smoked it and it just came pouring out of all the edges of the gasket. We just put the gasket in last week to, so I'm going to do what "jfoj" said and pull it back off and get the 15 grommets that the valve cover gasket didn't come with. And my cover isint cracked yet. Key word. But it was making cracking sounds when we were putting it back on. I'm certain if I pull it off again it will crack though. That's why I was looking for a metal replacement.
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Old 05-10-2015, 01:06 PM   #23
jdstrickland
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When you make comments like, "it was complete hell taking it off," then you probably broke it or something near by. My money is on a broken vac line, of which there are many.

Follow the intake from the air filter, it goes to the MAF, then to a large duct that makes a 90-degree turn to the throttle body. Inspect the nipple coming off of the 90, it is a common failure point and the massive vac leak that results will give lean codes.

Air enters the intake and is measured by the MAF for density. The density of the air dictates the amount of fuel needed. The fuel needed is a function of engine operations, and also a requirement for the CAT. The CAT wants the fuel ratio to be 14.7:1 because this results in an even distribution of molecules that when passing through the CAT where free electrons are picked up, the result is basically, water, air and CO2. If the mixture is lean or rich, then the CAT is not as effective as it should be.

What you have is a leak where air is entering the intake after the MAF. The unmetered air makes more air than fuel, and this is what lean means.

The O2 Sensors before the CATs are used to fine tune the fuel delivery to attain 14.7:1, and when the mixture cannot be fine tuned, or is constantly being tuned from one end of the scale to the other, then the computer will eventually throw a code to tell you that the exhaust is lean, rich, or all over the place -- P0170, P0171, or P0172 for Bank 1 (add 3 to any of these for the code for Bank 2). Codes ending in 0 or 3 mean that the fuel trim is all over the place, 1 or 4 means that the trim is lean, and 2 or 5 means rich.

The O2 Sensors after the CATs are used to measure if the CATs are doing their job. The exhaust that comes out should be cleaner than what went in. The signals for the exhaust going in can change within a range, the signals for the exhaust coming out should be flat.
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Old 05-10-2015, 01:39 PM   #24
jdstrickland
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Pull the cover off and cure the leaks, this is something you absolutely want to do.

I'm only suggesting that you should look at the vacuum lines while you are there. I expect that curing the valve cover gasket will not solve the problem. You have a problem with the gasket, but the gasket is not the problem with the lean. The problem with the lean will be a broken hose or two.

In a perfect world, the engine is sealed. That is, the intake, combustion, and exhaust are all separate from the crankshaft. There is some seepage, blow by, that takes place, and they use the intake vacuum to collect these fumes. The CCV system is responsible for this, and the orifice between the intake itself and the crankcase maintains the vacuum. The crankcase creates a certain amount of positive air pressure, so they put an orifice in the vacuum line to control the airflow.

I've not had a valve cover gasket give me a lean code. It might be possible, but other things in the same area are far more likely to be your problem. In theory, you could operate the engine without the valve cover and it would be fine. In practice you cannot do this mostly due to the mess that would result. As a kid, we would adjust lifters and rocker arms while the engine was running, we would turn the adjusting points to cause noise, then turn the other way to make the noise silent. So it is certainly possible to run an engine without the valve cover. You would not do it because it would make a huge mess to be driving around with no valve cover, but the rich/lean condition of the fuel trim would not be affected.

I'm just trying to encourage you to look at the vacuum hoses, not discourage you from fixing the valve cover.

Last edited by jdstrickland; 05-10-2015 at 01:40 PM.
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Old 05-10-2015, 04:24 PM   #25
traxnox
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Well, I'll fix the valve cover first so I can smoke it again and not have all the smoke just pour out of the valve cover, wish I could have gotten a video. Another question, as much as I doubt it, where does the line off the break booster lead to? I bought a new "suction pump" and all the hoses for it. All OEM BMW parts. Here's where I got stuck, that tube on the bottom of the suction pump runs behind the throttle body, I pulled everything out, including took the throttle body out, and still couldn't figure out where that hose went to, it went back further then I could even reach. So I gave up and pulled the old "suction pump" out of the tube and put the new one in. That point is litterly the Only thing I could possibly imagine leaking any sort of air. Do you have to take the intake manifold off to get in there and pull that hose out? I couldn't even reach it from under neath
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Old 05-10-2015, 04:45 PM   #26
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Originally Posted by traxnox View Post
Well, I'll fix the valve cover first so I can smoke it again and not have all the smoke just pour out of the valve cover, wish I could have gotten a video. Another question, as much as I doubt it, where does the line off the break booster lead to? I bought a new "suction pump" and all the hoses for it. All OEM BMW parts. Here's where I got stuck, that tube on the bottom of the suction pump runs behind the throttle body, I pulled everything out, including took the throttle body out, and still couldn't figure out where that hose went to, it went back further then I could even reach. So I gave up and pulled the old "suction pump" out of the tube and put the new one in. That point is litterly the Only thing I could possibly imagine leaking any sort of air. Do you have to take the intake manifold off to get in there and pull that hose out? I couldn't even reach it from under neath
You did the correct thing with the sucking jet pump, the brake booster vacuum hose connects directly on the back wall opposite of the throttle body and you cannot really access this without removing the intake.

Rarely does this hose or connection on the rear of the intake have problems.
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Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299
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Old 05-15-2015, 11:08 PM   #27
traxnox
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So today I pulled the valve cover off, cleaned the hell out of it. Took rtv and went all the way around the gasket grove, put it back together with high hopes. And turns out, I was not disappointed! The misfiring at idle is totally gone, cleared the codes and drove about 100 miles around town. They never came back. Car is also driving smooth as anything again. Thanks guys for the help!
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Old 05-18-2015, 09:09 PM   #28
Razz617
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I had the dreaded Bank 1 & 2 codes and a couple more codes thrown in for fun.
After checking a couple possibles, I did a smoke test. Saw a home made smoker on YouTube that I made, very easy, and tried it. IMMEDIATELY, I saw smoke coming from the DISA valve. After shelling out $358.00 at my local BMW dealership, I installed it. Took me about an hour to install and put everything back together. NO LEAK =NO CODES.
Try smoke test people. It worked for me.
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Old 05-18-2015, 10:10 PM   #29
traxnox
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Originally Posted by Razz617 View Post
I had the dreaded Bank 1 & 2 codes and a couple more codes thrown in for fun.
After checking a couple possibles, I did a smoke test. Saw a home made smoker on YouTube that I made, very easy, and tried it. IMMEDIATELY, I saw smoke coming from the DISA valve. After shelling out $358.00 at my local BMW dealership, I installed it. Took me about an hour to install and put everything back together. NO LEAK =NO CODES.
Try smoke test people. It worked for me.
Oh gosh! I would have plastered that o-ring with rtv before shedding $360. Unless the unit was wearing out regardless...
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Old 05-18-2015, 10:27 PM   #30
Razz617
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No. When I took out the old one, it was totally broken! The plastic had gotten really dried out and the mechanism was inoperable. The O-ring was still in good condition, but the rest of the unit was toast.

Last edited by Razz617; 05-18-2015 at 10:29 PM.
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