I've had the old girl for just
over a year now, and yesterday
clocked over 10 000 kms. It's
not been a bad year, with very
few issues except for the plug /
lead problem a few months back
and a couple of loose
connections here and there.
A few issues still plague her,
which appears to be legacies
left over from her UK days.
I continuously blow the 15 amp
fuse for the 'oil fans'. But I'm
not sure what or where these
fans are to start the check
process.
And even after all these kms, I
still have this annoying surging
/ bunny hop issue in the 2500 -
3100 rpm range.
When I first got her she was a
pig to idle and wouldn't hold
fifth gear below 130 km/ph.
There is a guy here in Melbourne
(FerrariFixer on FChat) who
waved his magic wand over her
and sorted those issues quick
smart. There was a lot of
imbalance in the two sides of
the fuel system and also she had
a vacuum imbalance. I was so
pleased when I bought her home.
One touch of the key and the
idle is perfect, even after two
weeks with no running. Best of
all is the great drivability. I
can now hold fifth down as low
as 40 km/ph and smoothly pull
away. A different car, thanks to
Phil.
BUT............................
The initial problem of this
surging / hopping continues with
no change.
Symptoms:
Driving along in any gear, but
lets pick fourth and fifth.
Fourth gear at 2500 rpm, is
close to 80 km/ph which happens
to be our speed limit for major
arterial roads. Fifth gear
places you at 103 km/ph, open
highway speed with just the
lightest throttle pressure. As
the car gets to 2500 rpm it
starts to surge slightly. If you
hold the same throttle position
or lightly accelerate the
surging becomes totally violent
and starts to throw the car
around in a backwards / forwards
motion putting untold stress on
the driveline components.
If you lift off and drop below
the 2500 marker, it goes away
nearly instantly. At this point
you can accelerate hard and push
straight through the 2500 - 3100
range without even noticing it.
It ONLY happens at the very
lightest throttle pressure.
Strangely enough, it seems to do
it more when the weather is
cold, and less as the weather is
really hot (ambient air temp 35
deg C or hotter).
Last week we took the car out
and did 500 kms over two days.
The drive home on the second day
was a nightmare. Trying to hold
the car at 100 - 104 km/ph
(legal limit) in fifth gear
became impossible. I'm riding
the 2500 rpm marker and had to
100% concentrate on the balance.
100 rpm over and the surging
started. A 100 rpm less and I'm
holding up the traffic. Many
times I had to drop to fourth
and then RPM was at 3200 and
over the band where the issues
are and drive for miles in
fourth just to give myself a
rest.
The car runs like an absolute
Swiss watch, except for in this
range. When I'm on the track or
punting hard, there is no
indication at all that the car
has any issues. It's only at
whisper light throttle levels.
Phil has the mixtures perfect,
so I'm sure it's not that. But
there is something going on that
is seriously impeding my
enjoyment of the beast, and
after a year of this I'm getting
towards the end of the tether.
Lately I've been experiencing
the same problem for a brief
flash around the 1800 - 2000
mark also. Especially in Third
and Fourth gears.
You know that horrid jerking
feeling when the car is running
out of petrol and bunny hops
back and forth a few times
before it finally dies and rolls
to a stop. Well that's the
feeling!!
As it's so specific to a rev
range, I don't know what it
could be. Fuel distribution
heads don't seem to go out of
calibration without affecting
the entire rev range. Ditto for
the two fuel ECU's.
Some things you might try (although
I have a feeling this is going to be
a difficult Gremlin
):
1. Send me a PM with your email
address, and I'll send you a copy of
Diagnosis Sheet 6 for the TR KE-Jet
Injection System and some
instructions on how to make some of
the more basic measurements.
2. After you've got the engine
warmed-up, try removing one of the
fuel pump relays so that you are
just running on a single bank and
see if the problem is still there or
not. Then replace that fuel pump
relay and remove the other one and
see if the problem is still there or
not when running only on the other
bank. When only running on one bank,
you might need to give it a little
throttle to keep it running at idle
(and the power will be 1/2), but I
think it would be a good clue if you
could determine if the problem is
really only occurring on one bank or
if it occurs on both banks.
If the problem is only occurring on
one bank, the next steps would be
things like measuring the current in
the EHA coil of that bank and seeing
if it's going wacky when the problem
occurs and disabling the
vacuum-controlled bypass valve to
see if that eliminates the problem,
but if you can get the information
from steps 1 and 2 above it could
help give direction.
I'm not 100% sure if it could or not
-- it's one of the things listed in
the Diagnosis Sheet 6 tests (and
reasonably easy to test), so it's
something I'd test/confirm anyway
just as part of some basic pre-tests
on any sick KE-Jet TR. Same thing
for the coolant temp thermister
resistances and making sure that the
+12V power is present and reliable
to the injection ECUs. If the
throttle micro switch is the issue,
the way it would appear in the
system would maybe be driving the
EHA erratically -- so IMO that's
maybe the "best" overall measurement
to make on a F113B KE-Jet without
Lambda to confirm/deny the health of
the electrical part of the F113B
injection system -- i.e., some
reasonable steady EHA current values
that decrease with temp/time from
cold start-up, steady lowish values
during constant warm-running
conditions, and the appropriate
increase (richness) for WOT, sharp
acceleration, etc. would say that
the electrical side is doing what it
should be.
Frankly, I'm not as convinced that
this couldn't possibly be a FD
problem as Robert is, so, without
any information at all yet, I'd say
he'd almost be lucky if this was an
electrical fault.
Last edited by Steve Magnusson;
01-04-2008 at
02:23 AM.
I'll try the fuel pump off trial
today, but I'm tipping that the car
will take more throttle to drive
with one bank out and probably won't
play up. As Jeff say's, it only
happens at the lightest throttle
settings.
Steve, what's this mean, "Frankly,
I'm not as convinced that this
couldn't possibly be a FD problem as
Robert is" (FD, what's that - Fuel
delivery?)
Well today was an interesting day. A
mate has this great electronic gizmo
and we fitted it up to the Testa
then went out for a run. First tried
it on the drivers side exhaust, so I
have to imagine that is the left
side of the engine the way the pipes
cross over. Someone here might be
able to confirm that.
Instantly it was obvious that the
car is WAY too lean. We took it out
into the traffic and finally got it
onto the freeway where I could
maintain some even cruise to
replicate this spasmodic jerking
that it's been doing for over a year
now.
The car runs worst at 106km/ph in
fifth. It's at around 2600 rpm here
and it will just start jerking
violently until it shakes the car
apart or you power on and drive
through it. Mixture was at 19.68
when it started jumping around. Stab
the throttle and it went to 18.5 and
the jerking goes away. Wide open
throttle was 15.8, but generally it
was between 18 and 21 all the time.
We then stopped and changed over the
lambda sensor to the other exhaust,
which I presume is the drivers side
of the engine. Even worse. 22's most
of the time at 20.5 when the jerking
started at 106 km/ph.
No matter how hard I drove it, I
couldn't get into the 14's. 15.7 was
the lowest I saw and that was giving
it hell in second gear. Idle
mixtures seemed better at 15.8 or
so, but as soon as I get moving it
just isn't getting any fuel at all.
Geez, no wonder I'm getting 25 mpg
out of it.
So, I've been told time and time
again to get it on a dyno with an
analyser up it's arse to see what's
happening, so now I've gone one
better and done some actual road
miles. Nest thing I suppose is to
try and tune some fuel into her??
It sounds like your on the right
track Robert. For tuning my car, I
finally had to "man up" and buy a
4-Gas Analyser to sample the exhaust
stream so I could adjust the fuel
mixtures correctly. There is a
thread or two on the procedure for
adjusting the TR fuel mixtures...but
I can't seem to find it. If someone
else finds it - please post a
link...
Even using a four way analyser, it's
still best to tune the car for
cruise and get the numbers as close
to 14.7 as possible. The only way I
can see to do this is either having
a mobile four way gas unit so you
can actually drive along on cruise
at 60 mph and check the numbers.
Even then you will have to stop and
tweak, then run again, check the
numbers, stop and tweak and so on.
Only other option is tune it live on
a dyno.
Idle mixtures have some importance
to get the car to idle right and
warm up nicely, but it seems cruise
mixtures are the most critical.
Problem with the KE system is there
is bugger all to actually adjust>
Steve M might have some clues or
feedback on this.
Did you buy a snap on 4 way or
something similar Jeff?
Your report that some enrichment
does occur at WOT, or when stabbing
the throttle, is a sign that the
electrical part of your KE-Jet
system is working (which might be a
bad thing since an electrical
problem could be easier to fix than
a hydraulic problem).
Were you able to confirm/deny any of
the electrical tests that I emailed
to you? You really don't want to do
any mechanical tweaking until you
are fairly sure that the electrical
stuff is working IMO.
Last edited by Steve Magnusson;
06-02-2008 at
05:33 AM.
Steve I haven't done all the tests
yet. Slack I know, but I was waiting
till I could get some gas analysis
done so I could report back in with
a bit more info. Today I had a bit
of a further tinker with the o2
sensor up its bum on both sides.
Both fuel heads are lean as can be.
Both around the same. 15.5 at idle,
19 at cruise, and off the scale 30+
on over run. For me it was
interesting that no matter what I
tried, both sides were bad. I was
sort of hoping that one side had
good mixtures and the other side was
crook, would have made it easier to
diagnose.
I was always of the impression that
the car had two fuel ECU's located
in the upper rear quarter on the
RHS. After today, it appears that
these are the ignition ECU's and
that there is only one fuel ECU
mounted on the LHS upper quarter. I
found this out by mistake. Laying
alongside the radiator over flow
bottle I found a small rubber tube
which had vacuum on it. I followed
it to the front of the inlet
manifold on the LHS but it didn't go
anywhere. Then I started looking
around and I found an empty nipple
where it appeared to go, on the
single ECU on the LHS!
From what I can see this must be the
fuel ECU and it needs to monitor
manifold vacuum, like a MAP sensor
does, probably so it can alter
mixtures. I stuck it back on, and
even though the car idled a little
better, my problem got worse and the
car actually leaned out even more!
It appears that it must have been
removed at some time in the past to
try and make the car actually get a
bit richer. I actually took it back
off again as at cruise the car
actually runs a little better with
it off and sucking vacuum, rather
than connected which just isn't
right!
From what I can see today the
problem is causing issues to both
banks. That sort of discounts
individual components causing the
issue. I have to look for components
that will affect both units
together. Temp sensor has to be the
first thing to check, and maybe even
the ECU itself. I can borrow an ECU
from another car and try it to see
if there is any improvement. Then I
suppose the next thing is to run the
full set of tests and see if I can
pinpoint any further component
failure.
Just to confirm. The 3mm Allen key
screws under the top cover of the KE
units, purely adjust idle mixtures?
Even with these now set slightly
rich at idle, the car is still
really lean at any throttle level.
So the only thing I played with
today was the idle mixtures and the
big brass bypass air valve to set
the idle speed and balance the two
banks.
There is no other mechanical
adjustment to richen the mixtures on
a KE Jet apart from idle mixtures,
is that right?
My car has no CATS and no O2 sensor
in the exhaust. Is this normal for a
UK spec KE Jetronic car? Does the
fuel ECU simply hold a flat file?
Having only basic information fed
into it, like engine temp and
throttle position, it has no ability
to make changes to the fuel curve
like it would if it was reading an
o2 sensor.
I expect that a car with CATS and an
O2 sensor wired to the fuel ECU
would be able to run an infinitely
variable fuel curve dependant upon
the input sources. Did any Testa's
run 02 sensors?
Last edited by uzz32soarer;
06-02-2008 at
04:12 PM.
I think you still have O2 sensors in
front of the where the pre-cats are
for US cars. Their functions are to
monitor the engine exhaust and so
the FI system can adjust the fuel
mixture accordingly.
My car has no O2 sensors. The
original exhaust would have looked
like image number one below. Number
29 is listed as 'plug for CO intake'
USA spec car with O2 sensors would
look like image number two below.
Obviously the USA cars have a
different wiring loom and fuel ECU
to take the extra inputs from the O2
sensors. Part number 1 shows the USA
spec oxygen sensor.
Here's two images just taken of my
exhaust manifold.
There is a blanking plug where the
CO intake is shown in the parts
drawing above. There are also two
other blanking plugs on each side of
the car as shown. Definitely no O2
sensors.
Disregard aspects of my first post
today. I was right after all, there
are two fuel ECU's as I just
confirmed from the parts book. The
single one on the LHS is the
ignition module and it does have
manifold vacuum going to it, Ferrari
call it the 'ignition module
depression hose'.
Now, this hose is not attached on my
car and obviously it should be, yet
without it I actually do get the
mixtures a little bit richer, not
much, but a point or so.
...The 3mm Allen key
screws under the top
cover of the KE
units, purely adjust
idle mixtures? Even
with these now set
slightly rich at
idle, the car is
still really lean at
any throttle
level....
It's more accurate to say that small
adjustments of the mixture screw
have a larger effect at idle because
the slits in the FD aren't opened
very much at idle (so a small
adjustment of the slit opening is a
bigger percentage change). At large
airflow (i.e., large slit opening),
these small adjustments are reduced
to a very small percentage of the
slit opening so not much effect on
A/F ratio at large airflow.
Quote:
Originally Posted by
uzz32soarer
...There is no other
mechanical
adjustment to richen
the mixtures on a KE
Jet apart from idle
mixtures, is that
right?...
Correct
Quote:
Originally Posted by
uzz32soarer
...My car has no
CATS and no O2
sensor in the
exhaust. Is this
normal for a UK spec
KE Jetronic car?
Does the fuel ECU
simply hold a flat
file? Having only
basic information
fed into it, like
engine temp and
throttle position,
it has no ability to
make changes to the
fuel curve like it
would if it was
reading an o2
sensor....
Yes, this is correct for a F113B TR
-- Your system operates similar to a
K-Jet without Lambda system where
the warm-up regulator has been
replaced by the injection ECU and
the EHA valve on the FD (to add
enrichment when cold or when you
blip the throttle).
Quote:
Originally Posted by
uzz32soarer
...Did any Testa's
run 02 sensors?
Yes, US, CH, and CAT versions.
They've got the added smarts to
dynamically vary the electrical
signal going to the EHA valve to
keep the average O2 sensor output a
0.5 volts during non-WOT
warm-running.
You've got the right thought that
both banks going from good operation
to bad at the same time implies that
it's something common to each bank
(if we can trust you that there was
prior good operation
).
Please advise if the electrical
tests show something wrong.
PS You shouldn't have that vacuum
hose disconnected from the ignition
ECU. This will cause the ignition
timing to always be very
significantly retarded. You won't be
happy if you have to replace the
ignition ECU -- it's hard to find
and pricey.
Last edited by Steve Magnusson;
06-03-2008 at
01:15 AM.
(if we can trust you
that there was prior
good operation)
Nope you can't trust me on that at
all. When I bought the car back in
'06, it wouldn't hold 5th gear under
140 km/ph and when cold it hunted
really badly, between 500 and 1500
rmp. Warming it up was terrible,
always thinking it had stalled and
then it would rev up again, then die
down. Once running (or warm) it
started and idled fine though.
Then I had a local Ferrari Fixer
tune it, and since then it's been
great, idles perfectly from cold
during warm up, and I can drive it
at 60 km/ph in fifth if I want to.
Totally different car. BUT!! It's
always done this jerking at 2500 -
3200 rpm, and tuning it didn't get
rid of that at all. It's taken till
now to actually get some cruise
readings to see what it's actually
doing, and obviously it running way
too lean. But on both banks pretty
evenly.
So no, I can't attest to "prior good
operation" but I remain hopeful that
sometime soon I will actually get to
experience the Testarossa goodness
the way it is intended to be, right
across the rev range with no
shortcomings.
I'll start on all those electrical
tests as soon as work loads allow,
and lets see what is discovered.
Ok . I am going to go out on a limb
here. If your car has no cats, and
no O2 sensor it is always working in
open loop. I have no experience of
fiddling with the Bosch K jetronic
on my TR. but I did quite a bit of
that with my Porsche which is like
one bank of the TR and I did run
open loop for a while without any
problems. I never could follow the
instructions for proper checking of
the system which I am sure Steve
gave you, but you can do so useful
tuning with a cheap 2 wire Bosch o2
sensor that you plug anywhere you
can in your exhaust and a voltmeter
and long lead wires. it will tell
you if you are rich or lean, but not
how rich, or how lean. In the
Porsche the best I can do is rich
sometimes, lean sometime. As you
noticed there is not much you can
do. But to check if your problem is
really due to fuel mixture you can
make sure the warm up regulator is
always "cold" That will enrich your
mixture, Beyond that the only other
semi easy way to adjust the mixture
with which I have any experience is
to fool around with the
counterweight in the air flow
sensor. With lighter weight the
lever moves more for the same air
flow and gives you more fuel >
richer!. Nasty but I like to fool
around. Not sure I would do that
with the TR! Hope this does not
confuse you further
Hmmm.....the Ke Jetronic on my car
has no warm up regulators either.
I've tried to adjust the screws in
the air flow sensor but cannot get
enough adjustment to get the cruise
mixtures even close to rich enough.
Work is a b1tch this week, but as
soon as I get a half day I'm going
to do all of Steve's tests, starting
with the temp sensor. Seems the only
way to chase down the issue, now
that I have confirmed that it is
lean right across the range.
Driving along in any
gear, but lets pick
fourth and fifth.
Fourth gear at 2500
rpm, is close to 80
km/ph which happens
to be our speed
limit for major
arterial roads.
Fifth gear places
you at 103 km/ph,
open highway speed
with just the
lightest throttle
pressure. As the car
gets to 2500 rpm it
starts to surge
slightly. If you
hold the same
throttle position or
lightly accelerate
the surging becomes
totally violent and
starts to throw the
car around in a
backwards / forwards
motion putting
untold stress on the
driveline
components.
Any ideas??
Don't know if someone mentioned
this, but one of my old cars did
this and it was a bad plug wire.
Check your wires if you've not
already done so.
TR coolant thermister resistance
test. Ambient air temperature here
today was 18 deg C. I ran the car
for three or four minutes to check
idle so it wasn't dead cold but
pretty close to cold.
Measuring from pin 21 to pin 2 on
the unplugged harness connector.
Rear ECU measured 2265 ohms. Front
ECU measured 2173 ohms. I estimate
my coolant temp to be around 20 - 25
deg C so looking at the sliding
scale on the graph, these figures
look about right.
Measuring between pins 1 and 13 on
the ECU Harness.
These results are inconclusive
probably due to the few minutes that
the engine ran prior to the test.
Rear ECU read 0.03ohms at rest and
open curcuit when throttle opened
even the smallest amount. Front ECU
read 0.04ohms and then straight to
open circuit.
I know this should have read 140
ohms on a cold engine, but this
didn't happen. I will redo this test
in a few hours when the engine is
dead cold again.
I removed the two fuel pump relays
then connected a wire from the big
positive on the starter to the white
wire with blue trace which I removed
from the starter. There was a small
audible click as I touched this
which I presume was the relay
closing?
I then tried measuring the voltage
between the two bottom pins and an
earth point as instructed. I got
zero volts yet I should of had 7-8v
on each. Both measured zero.
Then I tried the centre pin which
also had zero, and even whilst
pressing the airflow plate I had
nothing. So I may have an issue
here.
I did all of this with the ECU
connectors still off, so not knowing
where to go next, I reconnected the
two ECU's and tried again. Same
result. Zero voltage!!
Once the ECU's were connected I
tried to start the car and it took
ages of spinning over before it
actually fired. Don't know if that's
normal either?
Robert - perhaps this may be of
help. I suspect that the flexible
rubber (black) tube that you found
going into a canister that had
vacuum pulled through it is the
vacuum assist for the baffles in the
air conditioning / ducting system
under the dash. If you remove this
black tube from the canister
(reservoir) located over the left
rear wheel, the air venting in your
passenger compartment will no longer
work. That is, the ducting will not
change when you press the A/C
buttons from defrost to dash flow.
These ducts are vacuum assisted.
The important issue is that if the
vacuum tube is removed or violated,
then air will leak into the manifold
of the left bank (that is where the
vacuum is generated). This can lead
to a mixture problem. I know this
because at one time my ducting
failed to work (defroster would not
work). Upon finding the source of
the problem, I noted that the end of
the black tube had become dry and
cracked, and was no longer creating
an air-tight seal with the canister.
It was sucking air thereby
eliminating the negative pressure. I
clipped off an inch of the tube to
come to fresh rubber. Problem
solved.
You must have the injection ECUs
plugged in when you measure for the
8V at the airflow potentiometers --
so your getting nothing when they
were unplugged was the correct
result, but it's odd that you didn't
get the 8V when you plugged them
back in. The injection ECUs make the
+8V out of the same +12V on the red
wire at the water thermoswitch so
you might go back and confirm that
you've still got the +12V on the red
wire (I say +12V, but it's really
the output of the alternator so the
~14.5V is OK for what I'm calling
"+12V").
Okay, I've double checked the
voltage to the red wire on the water
temp sensor and that's fine at 14v.
So I pulled the fuel pump relays
again and hooked 12v from the
starter to the white / blue wire at
the starter to set the relay.
Checked both pins again, definately
zero voltage there. Also checked by
putting my negative probe to the top
pin and positive probe to the bottom
pin, looking for earth at the top
pin. Same thing - zero voltage.
So, looks like there is a definite
issue here. Could the system go into
some kind of 'limp' mode when there
is no voltage signal at these pins
or what would the effects be on the
fueling system?
Rob – I emailed you Fig 3 (the
injection system) from the 459/86 TR
wiring diagram for your model. It is
so wonderfully simple compared to
the US version
,
but it has the exact same
architecture for the wires going to
the airflow potentiometers so I
can’t see how it should work any
differently. It is true that I only
have Diagnosis Sheet N. 6 (for the
US TR) and your model is actually
covered by Diagnosis Sheet N. 5;
however, I have reviewed the actual
schematics of both, and, in both
cases, there is no reason why having
the ignition key “on” or “off” would
make any difference (as long as
you’ve got the red wire at +12V). In
Diag. Sh. 6, it does say “injection
ECUs connected and ignition key
‘on’” for the measurement conditions
at the airflow potentiometer wires
so it wouldn’t hurt to retry with
the key “on” (but I’ll be shocked if
it makes a difference -- my guess is
that “with +12V power applied to the
injection system” -- i.e. red wire
at +12V got confused into “with the
key ‘on’” somewhere along the way).
I’d be very surprised if you had the
exact same fault inside both
injection ECUs, so you might want to
try confirming that +12V power AND
ground is actually reaching the
injection ECUs. Having the red wire
at +12V is a very good sign that the
+12V is reaching them because the
food chain is:
+12V from battery -to- relay C
terminal 30 -to- relay C terminal 87
-to- 1/6 injection ECU pin 1 -to-
7/12 injection ECU pin 1 -to- 2-way
splitter -to- water thermoswitch
(and the other branch goes to the
throttle microswitch)
Since you are making the +12V
measurement at the end of this
chain, there’s a good chance it’s OK
at the ECUs IMO. Checking the ground
is a more difficult situation
because the food chain is:
Ground connection at engine -to-
3-way splitter where:
One branch goes to relay C terminal
31
One branch goes to 1/6 injection ECU
pin 2
One branch goes to 7/12 injection
ECU pin 2
Since your relay C is working, that
confirms that its ground connection
isn’t horrible, but it really
doesn’t guarantee that the other
ground connections are OK (if there
is a problem at the 3-way splitter).
Bottom line is that what you’d like
to measure is the voltage between
pin 1 and pin 2 right at each
injection ECU with everything
plugged in and while the red wire is
at +12V (or the engine is running)
-- should be +12V -- but this is
difficult without the special
interconnection box. I can’t recall
if you can remove the back connector
shell enough on the 25-pin
connectors to make a measurement
while they are plugged in.
If you do have +12V power between
pin 1 and pin 2 at the injection
ECUs, but no 7~8V between pin 18 and
pin 14, that would be a bad sign
IMO.
PS For the Throttle Microswitch
Resistance Test, the “140 ohm when
cold” part only applies to US
version TR. On your model (KE-Jet
without Lambda), it should be 0 Ohms
at idle and infinite ohms off-idle
regardless of cold or warm
conditions – sorry for the confusion
(and yours seems OK).
I forgot to add that you can try
making an easier-to-do resistance
measurement to see if the wires
going to pin 2 on the injection ECUs
are a good ground (but I think that
the functional voltage measurement
with everything plugged in and
actually working is a more reliable
test for determining good vs bad).
To make the resistance measurement:
1. key "off"
2. unplug both injection ECUs
3. unplug the large round C12
connector from the triangular black
box
4. measure the resistance from the
female metal pin 2 terminal in the
(unplugged) 25-pin injection ECU
connector on the harness side to the
engine block or cylinder head --
should be 0 Ohms (or a few tenths of
an Ohm maximum).
5. repeat step 4 for the other
25-pin injection ECU harness
connector -- should also be 0 Ohms
(or a few tenths of an Ohm maximum).
Last edited by Steve Magnusson;
06-06-2008 at
08:16 AM.
In Diag. Sh. 6, it
does say “injection
ECUs connected and
ignition key ‘on’”
for the measurement
conditions at the
airflow
potentiometer wires
so it wouldn’t hurt
to retry with the
key “on” (but I’ll
be shocked if it
makes a difference
-- my guess is that
“with +12V power
applied to the
injection system” --
i.e. red wire at
+12V got confused
into “with the key
‘on’” somewhere
along the way).
Did a fair bit of fiddling around
today. I needed to be comfortable
with the wiring schematics and make
sure I could understand it before I
went any further.
There was a bunch of things needed
to be checked, but before I did this
I ran the same test again, but this
time with ignition
on............bugger me if I now got
an 8v reading at the bottom pin.
Centre pin showed zero volts and as
I slowly pushed down with my finger
on the plate it went all the way to
7.98v with the plate right at the
bottom.
So it looks like that part is okay
after all.
So we learn something every day eh
Steve. Ignition ON required on a
late model Euro spec car.
Next thing was to do Steve's last
check which required getting in to
the back of the ECU plugs so I could
test things with the car running.
Wasn't too bad getting into the
plugs, just had to take care sliding
the factory shrink covering back and
then peeling the rubber back on
itself. Pics below.
With the car running I have a 14.45v
reading between pins 1 and 2 on both
ECU's.
Next I pulled out the triangular box
and removed the two round plugs
(without buggering them!). This box
simply holds three relays out of
harms way and is far from complex.
Pics below of the relays.
Starting with Relay C terminal 30 I
checked voltage with Ign ON and had
11.8v using terminal 31 s the
ground. Keeping Terminal 31 as
ground I checked pins 1 on each fuel
ECU and had the same 11.8v. All
good.
Then I held my probe on Relay C
terminal 30 as a constant voltage
and checked the earths on the two
relays D and E, and then on pins 2
of both fuel ECU's and got good
grounds on all four spots.
So at this stage I have passed all
tests, once we realized that IGN
must be ON to perform these tests.
Back to square one it seems!!
One thing bothers me a bit is that
relays D and E are listed as Control
relay for enrichment under
acceleration and control switch
relay for enrichment under
acceleration. This rings ALARM bells
to me as this is where my car
appears to be crazy lean. Could
there still be an issue with these
two relays? Are there further test
procedures to verify that these two
relays are working right, and are in
fact the right components as they
have different numbers as can be
seen in the images below.
I forgot to add that
you can try making
an easier-to-do
resistance
measurement to see
if the wires going
to pin 2 on the
injection ECUs are a
good ground (but I
think that the
functional voltage
measurement with
everything plugged
in and actually
working is a more
reliable test for
determining good vs
bad). To make the
resistance
measurement:
1. key "off"
2. unplug both
injection ECUs
3. unplug the large
round C12 connector
from the triangular
black box
4. measure the
resistance from the
female metal pin 2
terminal in the
(unplugged) 25-pin
injection ECU
connector on the
harness side to the
engine block or
cylinder head --
should be 0 Ohms (or
a few tenths of an
Ohm maximum).
5. repeat step 4 for
the other 25-pin
injection ECU
harness connector --
should also be 0
Ohms (or a few
tenths of an Ohm
maximum).
I did this one too Steve. 0.4 ohms
from one ECU and 0.3 ohms from the
other when going straight to the
rocker cover bolts.
):
).
Please advise if the electrical
tests show something wrong.