I've owned my '92 325is w/ 85K miles for 3 years now ('bought it from my dad, so know maint. history well, driven minimally winters). For the past 8 to 9 months, the engine "stumbles" (as the mechanic refers to it as) every now & then, usually after warmed up, & almost always in 1st gear as I'm popping the clutch, especially if I've been at idle for a while at a stop light - VERY annoying. It acts like its firing on only a few cylinders for a brief moment, makes a backfire sound under the hood (into the intake manifold??), & then runs fine for several miles before doing the same thing in the same setting. Gas mileage seems poor (17 city) & exhaust smells like unburned fuel. I've taken it to two mechanics - the 1st guy said after pulling the plugs, he notice oil on one, & so given this motor's known oil leakage problem, replaced the appropriate gaskets causing this. Problem seemed to go a way for a month, but came back (plugs were replaced as well). 'Took it to another mechanic, & asked him to bench check the coils (which I've heard is another problem w/ this car) - 'said they're fine, but felt stongly it was injector issue, not an ignition one & prescibed an expensive injector cleaning/gas additive. Problem improved maybe a bit. Any ideas? Problem seems to be worse when cold (under 30 degrees f) & when hot & humid (above 85). O2 sensor? Fuel pump or regulator? Oh - also, the lights flicker a bit at idle (alternator??).
'92 325is "stumbling"
- Thread starter MN Lakeman
- Start date
If the O2 sensor hasn't been replaced yet, that's a really good place to start, just to eliminate it as a problem. A bad O2 sensor could cause symptoms like this.
From PelicanParts -
http://www.pelicanparts.com/BMW/techarticles/JF-Tech/about_oxygen_sensor.htm
What are the symptoms of a bad oxygen sensor?
The biggest indicator of a faulty oxygen sensor is a noticeable decrease in fuel economy, along with a rich mixture. Now, this does not automatically indicate that the sensor has failed. Be sure to check all vacuum hoses for leaks as well as the ignition system, check the plugs, (are they fouled?) check the rotor, distributor cap, points, spark plug leads, and condenser (check all of these where applicable) Vacuum leaks and ignition problems are notorious for causing fuel economy problems. It’s a good idea to inspect and re-new the vacuum hoses every couple of years anyway. Other symptoms of a faulty sensor are a loss of power, (particularly when accelerating from a stand-still), overheating, and spark plug fouling, both of these are due to an increased rich or lean running condition.
From PelicanParts -
http://www.pelicanparts.com/BMW/techarticles/JF-Tech/about_oxygen_sensor.htm
What are the symptoms of a bad oxygen sensor?
The biggest indicator of a faulty oxygen sensor is a noticeable decrease in fuel economy, along with a rich mixture. Now, this does not automatically indicate that the sensor has failed. Be sure to check all vacuum hoses for leaks as well as the ignition system, check the plugs, (are they fouled?) check the rotor, distributor cap, points, spark plug leads, and condenser (check all of these where applicable) Vacuum leaks and ignition problems are notorious for causing fuel economy problems. It’s a good idea to inspect and re-new the vacuum hoses every couple of years anyway. Other symptoms of a faulty sensor are a loss of power, (particularly when accelerating from a stand-still), overheating, and spark plug fouling, both of these are due to an increased rich or lean running condition.