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1994 M43B18 - Rough idle, sometimes stalling, weird noise on first time takeoff only
M43B18 1994 318i e36
Anyone have any experience with these symptoms? Was told to check crankcase breather hose, mine feels floppy and soft as hell. it's pretty flaccid but I don't know if that's different from normal as it's my first time working on it.
When I start the car it feels like the revs can't tell where they need to be and sometimes its low enough to stall, sometimes gets close or other times just sits at like 400rpm. They can oscillate bouncing up and down between 1100 and 1600rpm too. The car will almost always completely cut out when I blip throttle to maybe 3k revs, it drops straight into a stall. When driving it can have a pretty crazy rev hang too, or other times pressing in the clutch to come to a stop makes revs drop into a stall.
sprayed carb cleaner around the engine and no vacuum leak found, all the hoses look alright except that breather (maybe?). Disconnecting the MAF makes it idle a bit more normally, though when I put the pedal down it cuts out acceleration at about 25% throttle, I dont know if thats the "safe mode" it goes into coming into action though.
Finally and probably the weirdest symptom that I just can not place, when I take off for the first time - or even start the car again rolling after a stall, the car makes some weird squelch or woosh noise coming from the passenger side in the engine bay! Never does it again unless the car has started again, is there some process that happens only at this first take off that I can nail the symptoms to? Thanks!
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Its most likely a vacuum leak, the rubber intake boot is the most common but that should all be checked or just replaced. If you've never run injector cleaner then its wise to do so twice a year.
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The boot looks like its hanging on alright, all other hoses seem okay too aside from the ones under the upper intake manifold that i can't get to yet. To be fair this car has sat before this for i think half a decade, Looks like ill have to try a cleaner. My american friend recommended seafoam too.
edit: side note I've seen warnings E10 (introduced in the UK recently) can dislodge build ups, this car only just started taking e10 recently. maybe a build up dislodged and mucked up somewhere along the way. Maybe its just E10 conspiracy theorists
Last edited by KyronXLK; 01-01-2022 at 10:40 PM.
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I would skip seafoam and go for an injector cleaner, if its available get royal purple complete fuel system cleaner, get 2.
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ah do they serve the same kind of purpose? Ill look out for it thanks!
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No, fuel injector cleaners use techron, some more than others as well as others chemicals. You don't have to find royal purple, there are lots of other top brands. You could get Redline or LubriMoly etc.
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If you already bought seafoam, save it for an engine flush before an oil change.
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This could be related to a problem I have diagnosed, its from likely the ABS Module. Solder joints that dry up and causes funny issues in idle, and going uphill, as they short out. Solution is to cut it open and resolder the joints. This has been the case for a lot of BMWs including the E3x, E4x and E6x series in our experience.
Its been well documented by me for the 4 Cylinder Ti but it may also help in this case. See If this helps, try this: http://www.318ti.org/forum/showpost....5&postcount=20
"So we've come to the conclusion that BMW just has parts laying around they decide to throw on cars for no reason."
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ooh okay ! ill give that a look over.
Odd update, today it started up and idled perfectly at like 800rpm, finally found a reader that can access at least the ECM (autophix 7910, a foxwell nt510 clone i suppose),and had a code 41 Air flow fault. cleared it and had a ride, gave it some beans when it reached temp to make sure and its idling perfectly fine, no stalling, no rev hang. odd, still makes the weird noise only taking off that 1 time it turns on as usual. The only other guy I saw trying to fix this issue on his m43 had his randomly fix it self too! I can only assume some kind of blockage happened and all the fiddling with it let it pass, or maybe the fact its freezing outside has something to do with it.
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My 1997 328IS 5 speed has been making the same noise on take off for a year or so.
Did you happen to determine what it was?
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