Re: 89 320i Intermittent Missing

["Sammy A. Haroon" <sah@xxxxxxxxxxxxxx>]

Hi,

First of, per Michel Potheau, back to the basics:  Check the fuel filter, fuel
pump, fuel pressure regulator, rotted line, loose or corroded electrical
connection, etc.  Then on to the electrical things.  You can basically sit in
the passenger seat and check currents and resistences on just about everything
in the car by unplugging the computer terminal and using the correct pins. 
Ofcorse you will need a good tech/info source like a Bentley, shop manual or
Helms, etc.  Also, I dont have the site handy which contains all the error
codes from the computer but I do have a copy at home.  I will scan it in and
send it to you.

I had a similar problem on a car I was working on.  It was a 87 325is.  After
just about testing everything, the problem ended up being the ETA fuel
injectors.  The last shop installed the incorrect injectors in the car.  The
easiest way you can find that out is by measuring the resistence across FI
terminals and checking them against the correct ones you ought to be using.

Other tricks are for fuel related testing, per Brett Anderson, which works
very well too, if you have tested just about everything else:
Install a pressure gauge in line with the fuel supply to the FI rail and tie
the gauge to the wiper.  Make sure you disconnect the wiper fuse.  That will
tell you if there is a pressure related problem when the car cuts off.

Another interesting one, per Mike Miller, is where couple of teeth on the fly
wheel can get chewed off by an old started.  Then, if you have the TDC pick up
sensor on the tran bell housing, it can give incorrect info to the computer.

I would recommend pin pointing some exact circumstances to the "lurch".  For
example, does it only happens when below 3500 RPM?  For that try driving the
car on a highway at a consistent speed w/o changing gears.  Does it happens
when its really hot?  (Some fuel line heating up causing vapor)  Once you can
do that, I would be able to help out more.

Good luck.

> I'm new to the list and was wondering if any of you have come across a very
> strange very intermittent problem that I've been having with my 1989 320i.
> 
> Occasionally while cruising or accelerating the engine will die for a second
> and then pick up again. This results in a very annoying 'lurch' in the car.
> There is no spluttering or fading power loss associated with this, the
> engine just seems to shut of for a second and then pick up again. This may
> happen 4 or five times during one long trip and then might not happen again
> for weeks.0
> 
> Once or twice the engine has just died for no reason at a steady tick over
> and started easily again. The car can also take a long time to start very
> occasionally and sometimes I have had to leave it for a few minutes before
> it would start. There is however no strong smell of fuel which I would
> associate with 'flooding' when the engine is hot. The Tick over is normally
> a little rough but steady.
> 
> I have checked all Wiring to the ECU, Engine sensors, Fuel Pump and Relay
> and all seem OK. Otherwise everything else is fine with the Car.
> 
> Has anyone come across a problem like this. I am considering paying a Bosch
> Engine Management specialist lots of 3=A3=A3 to run a full set of =
> tests on the
> car but as it is an intermittent problem they will not guarantee me that
> they will find it.
> 
> The Motronic ECU is supposed to store fault codes. Is there any way to
> download and analyse these without specialist equipment or is there any
> other way to diagnose this problem.
> 
> I would appreciate any suggestions anyone might have on this either via the
> digest or direct email.

- -- 
Sammy A. Haroon,  Taxila, Inc.,  770.234.9087
mailto:SAH@domain.elided
http://sah.home.mindspring.com/
- --
"Once spirit was God, then it became man, and now it is even becoming mob."
Thus Spoke Zarathustra, part 1, "Of Reading and Writing" (1883)

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