Give Gas=Stalls/backfires

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RBThompsonV

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alrighty, first time posting here, usually able to figure these things out on my own
1986 BMW 325es. (2.7 liter engine)
a couple of days ago it started acting weird... when you would floor it (stomp on the pedal) she would hesitate and choke (like the engine was about to stall)
but it would ONLY do this if you were flooring it.
Yesterday on my way to work, it crapped out on me completely, stalls as soon as you give it ANY gas. Seemed to idle fine though.

all of a sudden it was idling fine and then the RPMs dropped (down to around 300) then jumped back up. There's a VERY strong odor of gas from the exhaust and since this morning, she's begun to backfire when she idles.

Any suggestions on where to begin?

BTW: I DO have a video of the engine running if anyone would need to see it.
 
E30m42cab

E30m42cab

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Ah, the good 'ole '86 325es... used to have 2 of them... never had this kind of problem though. Does it sound like a deisel? Valves probably need adjusting.

Changed your plugs lately? Clogged cat? Actually that stuff is too easy... it almost sounds like your timing belt has slipped. Do you have trouble starting it as well?
 
Kirby

Kirby

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Sounds lik the MAF (Mas Air Flow) meter may be failing. When the MAF fails, it will usually idle just fine, but will kick and stutter at higher RPMS because it cannot sense the airflow and calculate the correct Air/Fuel ratio.
 
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RBThompsonV

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it WAS idling fine (occasionally stil does) but, even so, the slightest increase in gas (ie, you even ever so lightly touch the gas pedal) it starts to choke (and yes, it sounds like a deisel, LOTS of vibrations... RPMS drop drastically, and, if you keep the gas on it, it'll die...if you let it go, it'll sputter a bit but eventually recover and idle at around 800. weirder problem though is the backfire (though less detrimental to the forward momentum (as it currently has none). It'll also stall out if you dont give it gas and let out of the clutch (actually, in that circumstance it doesnt really matter if you give it gas or not, it'll die either way)

havent pulled the plugs to check them yet, it's getting fuel at the rail (high pressure end anyways)
Catty's gutted, so, no clog there.
How do i check the timing belt to see if it slipped (might be a dumb question.. but, all belts look fine) (or are we talking...timing belt might be loose?
it's always givin sporadic start issues.. sometimes it'll fire up with less than half a crank, other times it takes almost 10 seconds of cranking (starter is fine by the way)
the car DOES kick and stutter WHEN i can get it moving, however it doesnt matter if it's at 1200 RPMs or 5000 RPMs, it kicks and stutters the whole way, like it's dying then catching then dying and catching... it's like riding a fraking bucking bronco... embarassing too....
 
Doughnut

Doughnut

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You must remove the top timing belt cover to view the top section of the belt, then "bump" the engine over with the starter (coil lead off) to check the lower half of the timing belt, maybe a simple fuel fuel pump issue if it has just suddenly started doing it.
Weird...
 
E30m42cab

E30m42cab

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I've got a E30 325i sitting in my driveway that throws a code for the MAF, and o2 sensor, and it runs fine... even if it was the MAF, it would still runs smooth regardless if it was running rich. There seems to be either a timing issue or a spark issue, because the fuel isn't burning like it should (crappy plug wires, bad ground, gunked up plugs)
Have you pulled all the spark plugs to see what they look like? My 325e had really bad valve seals, and every time I'd park the car, the seals would leak oil into the cylinder and gunk up the plugs. How's your oil consumtion?
 
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RBThompsonV

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Oil consumption is actually not that bad (it does have 3 bad rings (compression checked) but, i havent had the time to rebuild. I'm getting ready now to pull the plugs and will let you know the condition.
 
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RBThompsonV

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replaces sparkplugs (old ones were not good), still has the exact same issue...NO improvement... any ideas? someone mentioned timing belt... any idea what the symptoms are for bad/loose timing belt?

additionally... ran seafoam through gas and crankcase, did oilchange, no improvement....
 
E30m42cab

E30m42cab

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And you checked your battery-to-body ground, and your block-to-body ground. Can you post a good pic of your plugs. Before you worry about your timing belt, swap out your ignition rotor (wouldn't hurt anyways.)
 
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RBThompsonV

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no, not sure what you mean though... they HAVE to be gettting spark as the car WILL idle.... just dies if you give it any gas, i can post a video if it helps (starting is also an issue, sometimes doesnt want to start, has to wait a little while like it's flooded
(fyi... those plugs are only about 4 months old)
 
E30m42cab

E30m42cab

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yeah, but the car WILL also run on 5 cylinders... and it will idle, poorly. This is why I pulled my engine. I just don't think you're getting spark, either becuase your timing is off, or because your wires are junk, or because you ignition cap/rotor is garbage. And obviously, you've got a lot of oil burning off... which is making things worse.

Please post the video!
 
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