I have a problem with my e30 325ic. Under hard acceleration at almost
exactly 4500RPM (although sometimes it does it at 5000) the engine sort
of "stalls" for a second, and then picks up again and pulls all the way
up to 6000 Rpm. It is exactly as though I just took my foot off the
pedal for a second (but I don't, lol), and happens consistently every
time. Other than that the car runs perfectly.
I have tried changing the plugs, but no change. I have checked for
vacuum leaks, but can find none. I took it to a BMW "specialist", and he
had it for 3 days, and has no idea what the cause is. He tried changing
the index ring for the crankshaft position sensor, but no change. The
only thing he could tell me was that it keeps registering "a lot of
different fault codes", but nothing specific.
Anyone else got any ideas? Any help much appreciated.
I'm not sure how sophisticated the M20 engine is but in my experience,
acceleration related problems point to something along the lines of a
worn distributor cap, althoguh thte fact that it only does it a
certain RPM makes me think it might be something else!
I had something similar on another car where it would cut out
completely at 4000 or thereabouts and it was the MAF but like I say I
dunno how the M20 engine works.
Change out your Engine Control Unit (ECU), which controls shift points,
ingnition/timing, and electronic fuel injection system.
Modern cars are like desktop computers. Its less expensive to
replace components than to analyze and repair faulty components.
If that doesn't resolve the problem, ship the new ECU back for
josh3i at hotmail . com
Coil? Its possible that the coil fails at a certain firing frequency.
Also once on an m10 I had a bad engine ground that would only fail when
the engine was at a certain RPM (the shakey shakey m10 would pull the
wire just enough so it would cut out just at 3700 rpm .. but if you
quickly went past 3700 or stayed below it was fine. Boy that was an
Assuming you are a typical E30 owner, you no doubt have met a few
others and stay in contact. One of them might pull thier ECU and test
it out with you. We've done a lot of this kind of troubleshooting
around here. Isolated a few problems that would have otherwise been
expensive to fix..
I had a similar problem several years ago on a volvo V40 T4 (200hp
turbo). Very similar symptoms.
Volvo chief mechanic found it on the third visit by watching the
engine at high revs, in a dark room.
He found an ignition component shorting to the engine. I can't
remember which component, but his method may help you physically
locate a short.
Thanks for the offer, but I am in the UK, probably a bit far.
I tried changing the coil this weekend, but no change. One thing I did
notice though, is that after changing the coil (even after going back to
the old coil) the engine ran rough for a while (hunting and
un-responsive), but then after a short run, it was ok again, which is
strange, considering the only thing I touched was the coil.
Still no closer
Thanks for the advice so far.
I was wondering Rob if you had solved the engine hesitiation problem.
I have a 325ix 88' 175k that has a similar problem at 5krpm. It
started right after I cleaned the airfilter for the first time. But I
dont' know if it is coincidence or not. Would a Mass air flow sensor
be the coulperate? Hope its not an ecu. Also, any help
Just a guess, but could it be bouncing off the rev limiter?
B.S. flag on the play! Index ring? That version of the m20 has a front crank
position sensor that reads from a pin in/on the harmonic balancer. See where
this is going?
but no change. The
10 yard penalty! That car can post maybe, what, 10 codes? I believe they are
all read from blinks on an instrument cluster light, check engine, perhaps?
Your BMW specialist is an idiot and playing you for a fool, straight up. Ask
him what the OBD Code Reader says. If he says anything except "You can't use
an OBD Code Reader," he's lying. Fault codes on the e30s were read from the
check engine light flashes.
Somebody correct me, please. My caffeine is wearing off. Then again, the AFM
is a good culprit, as well as the fuel pump or fuel pressure regulator. But
if the pressure is there, most likely AFM is binding or out of "adjustment"
(carbon track worn) in that rpm range.
Bill in Omaha
There is still an index ring (actually it's an entire plate) but
there is NO way it could cause this...
There are actually a few more codes than that depending on which
Motronic version the car has and the codes are very specific. Either
way, they can be read from either the check engine light flashes or a
code reader. You are correct in the statement that it's not an OBD
reader but that point would be missed by this quack mechanic. Replace
the fuel filter (always a good idea) and check the air filter. Neither
of these are the full cause but they could be contributing to it. Is
the check engine light operational and is it on or off? If it flickers
under acceleration, the O2 sensor is going and this WILL cause these
symptoms. This is not a part you want to change for the hell of it,
it's a bit pricey. You provide details and we'll get this sucker
Rob, I had a very similar problem with my 318i. Turned out it was a
bunch of grime in the intake snorkel from the airbox back. Made no
sense to me but a thorough cleaning savrue but e me buying a new ecu
and various other parts. Sounds too simple to be true but it worked
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