I have a 1987 T16 Aero. It isn't boosting fully, and my specialist blamed
lack of fuel on the Bosch mass air meter (Part Number 0 280 212 0050)

I got a spare "working" one off ebay, and tried it today. Immediate check
engine light and lumpy running, no go at all when the accelerator depressed,
like the cars being held back.

I immediately re-fitted the original, but have exactly the same symptoms!

Is there a way of re-setting the system, would I be right in suspecting the
engine management system has switched to an emergency setting.

Whilst my specialist blamed the original part, it did at least run fairly
well, even if I wasn't getting all the boost I wanted. It now exhibits all
the faults of the newer part I bought. Would a reset prior to using the
newer part be worthwhile?

A new part is getting on for £200, which is frankly beyond my budget for a
month or so, your help would be much appreciated as this is my only
transport currently and I don't fancy the train!

Al

In article <hFr8e.94278$Nr5.26781 (AT) fe2 (DOT) news.blueyonder.co.uk>,
alistairdore (AT) yahoo (DOT) com says...
Take it out for a few minutes and see if that makes any difference. It
should at least remove the stored check engine light and take you out of
the limp home mode.

If not, other option is remove battery for a couple of mins. But then
you would lose any stored radio settings.
--
Carl Robson
"Sorry Sir the meatballs are orf"
(The poster formerly known as Skodapilot)
http://www.bouncing-czechs.com

It sounds like your '87 has Bosch LH 2.2. Was the head gasket replaced
recently? Has it run poorly since then? Could be that the cam timing is
off. If no, the best way to figure this problem out is to check the
operation of the system with the help of the o2 sensor. Sometimes the
AMMs go bad. Sometimes, they can be adjusted to bring back normal
operation. It does sound like it could be rich, or possibly retarded cam
or ignition timing. first check that the timing is set to 16 BTDC at
idle. Second, check o2 sensor operation. If the o2 sensor heater fuse is
blown, or of the heater is otherwise non-functional, it will also not
run right, either. If all this is good... There is a method of AMM
adjustment. I do not know how equipped you are to DIY this, but it is
not too hard with an DVM and a screwdriver...

Basically, remove plug from AMM and twist screw CW and CCW 'till the
'average' o2 voltage is 0.5v.

KeithG

Al wrote:

"Al" <alistairdore (AT) yahoo (DOT) com> wrote


Did the "new" AMM have the exact same part number on it as the old one?
There's different revisions of LH Jettronic and if you plug in the wrong AMM
you'll damage the computer.

Al wrote:

I'm not entirely sure - but the air mass meter may use the hot wire method.
Certainly at the age of your vehicle it's possible that it's contaminated and
misreading.

I presume there are safe methods available that'll simply clean it. Given that
Bosch air mass meters have beeen fitted to millions of cars - I'm sure you'll
find some google help or the like.


Graham

Al wrote:

Here's some advice found on google quickly...


" Air Mass Meter Diagnosis.

Simple Functional Diagnosis of AMM. [Editor] The classic test of AMM failure is
to disconnect it; if the car runs better, then the AMM is at fault. But here are
the OEM tests per the OEM manual for Bosch 2.4 (the-016 AMM):

Check the ground point of the AMM:

ignition off; disconnect AMM
connect ohmmeter between ground and terminal 1
should be 0 ohms
if not 0 ohms, check the ground point on the intake manifold
Check signal from AMM:

clean off sensor connector, removing any corrosion
-start engine
connect voltmeter between ground and back of terminal 3 on back of connector
should read approx 2.3 volts.
if not approx. 2.3 volts, substitute another AMM
Testing AMMs and Calibration. This is a response from Python Injection
(rebuilders of AMMs) to a question about testing AMMs.
From: Joe Evert, Director of Engineering, Python Injection
Subject: Re: Technical Question about AMM
The reason the OEM doesn't give a test procedure for calibrating the air mass
meter is two fold. First of all BOSCH Hot Wire Air Mass sensors are not
linear devices like a throttle position sensor. The output does not change the
same amount for a given air change. To make it short, most linear sensors will
give you say... 1 volt for 100cfm air flow, 2 volts for 200cfm air flow, 3 volts
for 300cfm airflow etc. This is a linear device. Bosch hot wire sensors are not
like this. They change a great deal at low air flows but once the air flow
increases past a certain point, say 50% of what the engine can draw, they change
very little. This makes the sensor very accurate at low to moderate air flows
and good enough at high air flows. Just a small amount of inaccuracy at low RPM
and the vehicle will run terrible. If the voltage for a given air flow is off by
100 milli volts at low RPM the car will barely run. At high RPM A 100 milli
volt deviation will not even be noticed. Because of this it makes it next to
impossible for the technician to accurately diagnose the air mass in the field.
We use a calibrated flow bench that measures the exact CFM air flow to then
compare the voltage to. This is not practical in the field because temperature,
altitude, humidity and the mechanical condition of the engine will affect how
much air the engine is drawing in. So just to say that the Air mass should have
xx.xx volts at idle would be completely false since all these parameters must be
accounted for. Also even if a range is given just a small amount of deviation in
the output causes poor performance.

So what are you to do? For on-vehicle diagnoses the best way is just unplug it
at idle; if the vehicle runs better it is most likely bad. This is because if
the air flow sensor is off voltage at high RPM it will also be off at idle. Also
if you are experiencing repeated failures you probably have a defective air box
thermostat. This little thermostatic bulb is located in the air filter box and
controls the hot air into the engine. When this fails it fails in hot air mode
and routes hot air from around the manifold into the air intake. This will
destroy the air mass meter in no time. "


http://www.volvoclub.org.uk/faq/Engi...injection.html


Graham