vacuum leak (inspection rejection part II)

[nookatee]

i've broekn down and brought my car to the dealership to figure out why she's not passing inspection. Here are the original numbers from my second failed inspection:

HC ppm @ idle: 0833 0220
CO % @ idle: 06.22 0.120
HC ppm @ 2500rpm: 0626 0220
CO % @ 2500rpm: 03.55 01.20


and here are the numbers from my dealership expedition:

HC @ idle 336 220
CO @ idle 3.89 1.20
HC @ 2.5K 184 220 <----PASS!!!
CO @ 2.5K 1.94 1.20


the only thing I've changed is that I replaced the valve cover gasket and the car was much warmer the second time around. I've discovered I have a vacuum leak. I've heard it's a ***** to figure out where the leak is coming from, so I figure it may be simpler to replace all the vacuum lines? I'd like to hear some opinions. Thanks.
Ramy

[Wayne 962]

Did you run the codes to see what it was putting out?

-Wayne

[Wayne 962]

Also which car do you have?

-Wayne

[nookatee]

I originally went to the Dealership because the place that I went to before that to do the diagnostics couldn't get into the module. I figured that maybe they didn't have the right BMW ish so I set an appointment up with the dealer. He couldnt' get in either, saying that there's probably some kind of electrical problem (i don't remember exactly what he said). I tried the gas pedal thing, but I think my bulbs are burnt out because the check engine light doesn't come on when I start the car.
My car is a '93 325i.

Are there any good articles on removing the Intake manifold to get to some of the vacuum lines? The bentley manual is pretty vague on this one.
Thanks,
Ramy


Also just occurred to me, other than changing the valve cover gasket before this inspection, I also used BG 44k injector cleaner. The engine had been running about 20 minutes longer than the previous two inspections as well.

[nookatee]

the guy at the dealership said that these cars rarely fail inspection and if they do, it usually means they've got one foot in the grave. I don't want to believe him.

[blkongry]

Well, that's got to be a bit upsetting to hear a guy tell you if it doesn't pass emissions, then it usually has one foot in the grave. That's hooey, too. It's just an engine like any other, and you are just barely over the limits, so it sounds like your mix is a bit too rich. I mean, were talking about hydrocarbons... unspent fuel. That means a rich mix, or, if there is something wrong, it usally means blown head gasket, cracked cylinder head, cracked piston rings, or cracked piston. The closest one to what you might have is a blown head gasket, but that will show up on a cylinder compression test (and with white goop in the oil and whitish smoke out the exhaust).

Well, seeing how much of an improvement you had with running the engine a little longer, that tells me your engine is probably fine, just running a bit rich, especially if you have a vacuum leak.

Wayne has a nice article on here some where on how to change out injectors. It walks you through disassembling of the engine down to where you can access most of the vacuum lines. From there, I'd just have your car at an idle, then wiggle some of the vacuum lines around. If you wiggle one around and get a flutter in idle RPM, then that is probably your culprit. Or, if it's bad enough, you can probably hear it.

Get that fixed, run your car nice and hot before testing, and I bet you'll pass. In fact, if you've been running rich, then your exhaust is probably already kind of 'loaded'. I bet if you took the car out right now and ran it hard for a while, then made sure you tested it right after, you could probably get it to pass... heat the exhaust up enough to burn out any residue and it'll do it, but you still need to get that vacuum leak fixed regardless. Better to pass for the right reasons that not.

[nookatee]

Thanks a lot for the support blkongry. Even though the tech knew what he was talking about, it sounded like he wanted me to drop some clams for him.
Anyways, I've looked at the Fuel Injector article and it doesn't really get into how to remove the intake manifold. Most of the vacuum lines, unfortunately, snake under that manifold. I've tried removing the manifold, but it proved a bit tricky. The Bentley manual is a bit vague, at least for my n00bie eyes. it says to "disconnect harness connectors, vent hoses, and air bypass hose(s)" from under the intake manifold. i have no idea what those are or how to figure out what they are if they're UNDER the manifold.
any insight?

[blkongry]

Unfortunately, I can't help you there. I've never had to take mine apart, so I don't know what's under there, other than how literature describes it... and you've got as much access to that same literature as I do. Hopefully someone on here has had their hands in there and can give you more insight.

Sorry.

[Wayne 962]

Take a look at this before you decide you're engine has one foot in the grave:

http://www.pelicanparts.com/bmw/techarticles/Borrowed/mult_engine_rebuild-1.htm

-Wayne

[nookatee]

I pulled the spark plugs last night and, after having changed the valve cover gasket, I noticed some oil on the last spark plug. It was all over the threads. Is this indicative of blown piston rings? and does this mean i'm looking at rebuilding the engine?

[blkongry]

Doubt it... probably just pooled oil from a spill or something during a prior oil change or chainging out that valve cover gasket. Is it close to the oil fill location?

How do the plugs look on the electrode? If you had enough oil seeping up from your pistons to go up and around the spark plug threads, you should be bellowing out clouds of blue smoke from your exhaust.... and with that emissions test, you aren't.

I bet it's just a vacuum line causing your engine to run a little rich. Did you do a compression check on you cylinders? That will rule a lot of things out... it's good for a 'peace of mind' check.

[nookatee]

how much should a compression test run me? i've never gotten one before.

and yeah, the plug with the oil on it is the one closest to the filler cap. Unfortunately all the plugs, or rather their electrods, have a lot of carbon on them. Which from what I've gathered means the engine is running rich wich is no real surprise.

[blkongry]

If I were you, I'd just do it myself... you can get a compression test gauge down at your local auto parts store (or Pelican may carry them) for from $30-$60 (which is about an hour's worth of labor at a cheap shop). Here's what they look like... http://www.jcwhitney.com/autoparts/ItemBrowse/c-10101/s-10101/p-100000185913/mediaCode-ZX/appId-100000185913/Pr-p_CATENTRY_ID:100000185913 ...not sure what the expected compression should be, but if all the cylinders are the same, then you can be pretty sure they are all fine (a small deviation between them is normal).

You just screw the gauge into a spark plug hole, turn over the engine a couple times, then check the compression of that cylinder on the gauge. Record it, then check all the rest. If they are all over 100-something PSI, then you are probably just fine.

Yep, a little carbon on the plugs shows running rich, which fits with your not passing emissions. I'm pretty sure you just have a minor vacuum leak leading to the fuel/air mix being a bit off. Find that gremlin and you should be fine.

[nookatee]

how do you turn the engine over? Never done that before either. I know there's like a bolt or something at the front end of the driveshaft and I'm guessing you have to turn that, but i'm not too certain.

[blkongry]

LOL... sorry... you just use the key in the ignition and let the starter do the work You only turn it over a couple times, and if you pull all your plug caps, you ensure the car won't start. It just needs a couple cranks on each one to get the pressure up. Total piece of cake.

[nookatee]

Thanks for all the help. I'll let you know how things turn out. The clock is ticking....

[nookatee]

I've gotten a second opinion and was told that my air flow meter is dead. Would this cuz the engine to run rich or lean???
I have a hunch that the mechanic at the dealership didn't actually look at jack **** when he checked my car out. He said my vanos unit was shot. Then when I talked to him further, he said that the sound that lead him to believe that could be a loose spark plug. I tightened all the plugs and viola.... no more ticking.

[parolof]

to find the vacom leak, Have you tried the startgas trick ?
- i.e. spraying a short burst of startgas over the intake manifold - with engine idle - close to engine block.
Any leak in the intake manifold would pick up some of the startgas - and engine would shortly rev up.
It is in fact possible to pinpoint a leak this away - using the startgas bursting smartly.
Be careful though - by nature startgas is HIGHLY flammable.

[blkongry]

Yeah, a MAF (mass air flow) sensor could definitely skew your mix. If it's off, it won't meter in the right amount of fuel according to the amount of incoming air.... makes sense. I'm surprised nothing popped up on the ECU if the MAF was having problems, but it could just be slightly skewed, which is why your readings are just slightly high.

http://www.pelicanparts.com/BMW/catalog/images/BMW_fuelinj/masssensor.jpg Pelican has it for about $320.

[nookatee]

well, after talking to two mechanics, one being at the BMW dealership, it sounds like my ECU is having issues of its own. The guy at the $tealer$hip couldn't get into it to pull the fault codes. Later on I found that the bulb for the check engine light was pulled out previous to my purchasing the car. More and more I am thinking that i got hosed.... :-/