Trying to find VACUUM LEAK- Need advice

[Warren N.CA]

from those who "been dere, done dat."

1990 325is M20, Manual.

Motor will stumble and almost die, after running fine for a while. It's worst just above idle, and the idle will hunt from 500-1200RPM, rapidly, then die. It also happens at any speed, including highway cruise. CHECK ENGINE light comes on intermittently during these episodes.

Stomp test reports 1222 (I am told this means vacuum leak.).

Today, I went under the hood with the motor running and sprayed WD40 on all the vacuum hose fittings that I could identify, looking for the tell-tale engine speedup- but no dice. Not surprising, because the car was not acting up at that time. Maybe I'll take the WD40 with me tonight when I run my errands, and try it while (if) the car is doing the bad thing. First experienced this several weeks ago, and then nothing more until last night.

Any pointers as to how to proceed will be appreciated!

[Unregistered]

For starters, check the dipstick O-rings by pushing down hard on it while the engine is idling roughly. FPR vacuum can be toast, but as it snakes below the intake manifold, you'll not be able to spray there, which is also sight of other vacuum leak posibilities. Oil filler cap gasket? Brake vacuum assist? Idle control valve? Loose clamps on intake boots? Micro-cracks in same?

[632 Regal]

Ditto, look for the stupid stuff first, then go to the more drastic R&R methods. I searched on mine 3 times before I saw the intake boot (after the AFM) slipped off the bottom side of the intake opening...stupid stuff...

[Warren N.CA]

run low on stupid stupid stuff. Everything that I can see looks really phat. The car was gone through professionally with a fine tooth comb 4/02, and the AFM boot replaced because it looked old and ratty. I cleaned off the dipstick O rings with a rag, and wiped out the area of the tube where they seat. If only it would just break and STAY broken.

Ditto, look for the stupid stuff first, then go to the more drastic R&R methods. I searched on mine 3 times before I saw the intake boot (after the AFM) slipped off the bottom side of the intake opening...stupid stuff...

[Unregistered]

My O-rings LOOKED wunnerful. But, they weren't. Very cheap fix. Get somebody with a skinny arm to reach under the intake manifold and check the seating of the FPR vacuum tube. Better yet, get ~16" of new tube and put that on. Is your valve cover battened down properly? Oil filler cap got new gasket? If not, hardware store has neoprene big washer in exactly the right size, for ~50 cents.

[632 Regal]

mann, this sounds like a lengthy post with lots of new stuff inserted between the lines. Have you completely cleared the codes and started from a frest start? I'm tellin you its something stupid. Do the clear codes and we will start from there.

[Warren N.CA]

It ran perfectly last night. The dip stick had some grimy oil on O rings, and cleaning that off might have fixed it. I will also replace the oil filler gasket. I'd like to clear the codes so I can tell if it has recurred, even momentarily

mann, this sounds like a lengthy post with lots of new stuff inserted between the lines. Have you completely cleared the codes and started from a frest start? I'm tellin you its something stupid. Do the clear codes and we will start from there.

[Bill R.]

something has happened outside of the lambda control range...by this I mean that the dme monitors the O2 sensor and is able to do some adjusting to the fuel mixture within a narrow range to correct various deficiencies such as richening it up slightly to correct a small vacum leak or leaning the mixture out if its getting too much fuel... The range that it can correct if fairly narrow, it can't work miracles in fuel systems control... So anyway that code comes up if for some reason its gone lean or rich outside of the range of control, which would indicate a fairly good sized vacum leak or its running rich outside the range of control, a bad diaphragm on the fuel pressure regulator allowing fuel to be sucked into the intake manifold through the vacum line going to the fuel pressure regulator. I doubt that the gook on your dipstick orings was enough to trigger this code...
To clear the code you can do the stomp test and read the codes then after the codes are done flashing hold the gas pedal to the floor for 10 seconds or so. then shut the key off and repeat the stomp test to see if it cleared the code, if not you can try again. On some cars that won't work so then you have the option of disconnecting the battery for a couple of minutes or waiting until after you have done 60 starts on the car and it will clear itself as long as the original cause of the code has been fixed... So if you start the car 3 times a day thats 20 days and the code clears itself if the problem has been fixed.

from those who "been dere, done dat."

1990 325is M20, Manual.

Motor will stumble and almost die, after running fine for a while. It's worst just above idle, and the idle will hunt from 500-1200RPM, rapidly, then die. It also happens at any speed, including highway cruise. CHECK ENGINE light comes on intermittently during these episodes.

Stomp test reports 1222 (I am told this means vacuum leak.).

Today, I went under the hood with the motor running and sprayed WD40 on all the vacuum hose fittings that I could identify, looking for the tell-tale engine speedup- but no dice. Not surprising, because the car was not acting up at that time. Maybe I'll take the WD40 with me tonight when I run my errands, and try it while (if) the car is doing the bad thing. First experienced this several weeks ago, and then nothing more until last night.

Any pointers as to how to proceed will be appreciated!

[Unregistered]

When I mentioned the dipstick O-rings, I should have also noted that you should go with OEM O-rings: I put some 50 cent fatter hardware store neoprene O-rings on mine, and it sealed up perfectly. However, after a few weeks these O-rings sorta got fried in place, making the dipstick very hard to pull out.

I have not checked yet, but there is probably another O-ring or similar seal at the bottome of the dipstick tube, where it fits into the oil pan. That will need attention/replacement too, as well as cleanup of collected crud down there. BTW, if there IS oil leakage at the base of the dipstick tube, then air can leak IN via the same path the oil leaks OUT. Fix it.

Also, on the oil filler cap: I used a hardware store neoprene washer, which was exactly the right size. I first removed the stock washer, then put on the new one, then put the stock one back on top of that. That way, the stock washer is still mated with the valve cover lip, and won't get fried on, but has the new washer behind as a shim for a tighter seal.

Valve cover: Yes, I know it's supposed to take a dry gasket, without sealant. But, it was leaking, so I put a thin layer of gasket sealant on top and bottom surfaces of the old gasket, replaced the valve cover, and re-tightened to spec torque. The excess sealant oozed out the sides, so I waited overnight 'til it congealed, then trimmed excess with a razor to make it look purty.

Replaced your FPR vacuum tube, and similar tubes, yet? Mine LOOKED fine, but was literally toasted through in places not easily seen, so leaked bigtime. That meant the FPR was not doing its job properly, so injectors had wrong pressure and air/fuel mixture was off = poor performance.

BTW, the prior owner and BMW dealer (who is very well paid to know better) had totally neglected all of this easy fix. So, the car idled and accelerated poorly, the prior owner despaired of even bigger BMW dealer repair bills, so fire-saled the car for $3,250. New O-rings, vacuum tubes, and gasket sealant cost me ~$6.50 to remedy these problems. If you can think of a cheaper way to get more bang for your maintenance buck, let me know.

[535ise]

For starters, check the dipstick O-rings by pushing down hard on it while the engine is idling roughly. FPR vacuum can be toast, but as it snakes below the intake manifold, you'll not be able to spray there, which is also sight of other vacuum leak posibilities. Oil filler cap gasket? Brake vacuum assist? Idle control valve? Loose clamps on intake boots? Micro-cracks in same?

Sorry for the dumb and slightly off topic question but what's the connection between an (intake) vacume leak and a crank case leak(dipstick o-ring's) ?

The reason i ask is because i use an oil catch tank rather than venting the fumes back into the intake below's and was wondering if I was doing some thing wronge ?

(This picture was taken before i tidied the wiring up)



Cheer's

Andy