[v12-engine] Yet again, idle and emissions problems with a 6.0LV12

In reply to a message from palmk@nettally.com sent Mon 25 Jul 2016:

Yes Kirby. All is good in this Department.

The 36CU will flag a code FF44/F45 is either O2-sensor is not
providing feedback.

Steve–
The original message included these comments:

Have you ever checked the voltage to the heaters?


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In reply to a message from sbobev sent Mon 25 Jul 2016:

As shown in the first 4 pictures, and as discussed previously
on this forum, I believe that the ‘‘Adaptive Idle Fueling Trim’’
is my enemy:

http://www.jag-lovers.org/v.htm?id=1402280159

Will disconnect the battery overnight to clear the memory and
will check with DMV if they will allow me to re-take the test
w/o extensive engine work.

Steve–
The original message included these comments:

The 36CU will flag a code FF44/F45 is either O2-sensor is not
providing feedback.


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In reply to a message from sbobev sent Mon 25 Jul 2016:

‘‘Adaptive Idle Fueling Trim’’ is normal stuff for fuel
injection and what you want. Pulling the battery and
reseting it will put you in an unknown condition, could be
way rich or way lean and you can’t know until you re-run
the smog test and most likely get worse results.

If you’re 100% sure of your rotor, cap, wires and O2
sensors, double checking the water temp sensor makes sense
and I’d look for vacuum leaks in places like the intake
runners and injector seals. A little extra O2 in one
cylinder will throw off the ECU and mess up your numbers
but may not make a noticeable miss.

And then there’s always the catalytic converters, it’s got
to be hot to do it’s job, too cool at idle will lower it’s
efficiency and as they age they also get less efficient.
‘‘Modern’’ injection systems have pre and post cat O2
sensors specifically to keep an eye on cat efficiency.–
mike waldron
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In reply to a message from mike waldron sent Mon 25 Jul 2016:

Hi Mike:
Thank you for the 2nd response. If you take the time to read
through the original thread, you’ll see all of these
questions addressed.
Specifically:

  1. I am 100% sure there are no faulty components
  2. I am 100% sure there are no vacuum leaks
  3. Cats are fairly new Magnaflow 3-way converters, not the
    original 21+ years old equipment

High values for HC and CO normally suggest rich fueling or
misfire, but there is nothing in my findings that supports
this notion.

Steve–
The original message included these comments:

If you’re 100% sure of your rotor, cap, wires and O2
sensors, double checking the water temp sensor makes sense
and I’d look for vacuum leaks in places like the intake
runners and injector seals. A little extra O2 in one
cylinder will throw off the ECU and mess up your numbers
but may not make a noticeable miss.
And then there’s always the catalytic converters, it’s got
to be hot to do it’s job, too cool at idle will lower it’s
efficiency and as they age they also get less efficient.
‘‘Modern’’ injection systems have pre and post cat O2
sensors specifically to keep an eye on cat efficiency.


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In reply to a message from mike waldron sent Mon 25 Jul 2016:

Normal for EFI, agreed, but in my case, I found out that
forcing the engine in open loop smooths the idle
significantly.
The car always seems to tun better after the battery has
been disconnected. At least for a little while…
Best regards,

Steve

PS.
I also installed bypass switches that allow me to ‘force’
the ECU to run off the base fuel map. Second picture here:

http://www.jag-lovers.org/v.htm?id=1419988589

The idle emissions failure was in in normal mode, closed
loop though.–
The original message included these comments:

‘‘Adaptive Idle Fueling Trim’’ is normal stuff for fuel
injection and what you want. Pulling the battery and
reseting it will put you in an unknown condition, could be
way rich or way lean and you can’t know until you re-run
the smog test and most likely get worse results.


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In reply to a message from sbobev sent Mon 25 Jul 2016:

Steve,

One surefire method to detect misfire is put your hand a few
inches behind the tailpipes. The exhaust flow should be
smooth. An occasional or rhythmic puff indicates a misfire
and it might not be detectable any other way.

Have you done this test?

Mike–
The original message included these comments:

High values for HC and CO normally suggest rich fueling or
misfire, but there is nothing in my findings that supports
this notion.


mike waldron
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In reply to a message from mike waldron sent Mon 25 Jul 2016:

Yes Mike, many, many time. No pulsation from the exhaust.
I also have a little hand-held gizmo that works on induction.
Allows me to test rpms an individual cylinders.
All are the same.

Steve–
The original message included these comments:

One surefire method to detect misfire is put your hand a few
inches behind the tailpipes. The exhaust flow should be
smooth. An occasional or rhythmic puff indicates a misfire
and it might not be detectable any other way.
Have you done this test?


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In reply to a message from sbobev sent Mon 25 Jul 2016:

Since you have some fun tools, do you have a wide-band O2
sensor so that you actually know what your mixture is?

With a wide-band O2 sensor you’d know for sure if you’re
running rich and by how much.

I’ve used this one on several projects:
http://www.innovatemotorsports.com/products/lc2.php

It will let you know what your mixture truly is and even
let you ‘‘trim’’ where lambda is, so the ECU thinks it’s
operating at 14.7 but it’s really 13.5 or whatever you’d
like.

Mike W–
The original message included these comments:

I also have a little hand-held gizmo that works on induction.
Allows me to test rpms an individual cylinders.


mike waldron
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Steve,

Would this not mean that “default” values are working better than “learned”
values.

Which suggests that either there is an input sensor tolerance problem (MAP,
coolant, air temp) or an output (injector) tolerance problem - (ie delayed
opening or closing or available voltage)

The fact that it is close would suggest that it is not a gross error, rather
a % out of whack type error. Thought. Has the MAP sensor hose got any fluid
in it? Does the MAP sensor hose hold vacuum? (ie is there a pin hole leak in
the sensor diaphragm)

Your car also has a part load air/oil breather system that feeds into the
rear of the intake manifold. Is it possible this is sucking in a small
amount of oil? Not enough to foul plugs, but enough to elevate the HC
reading?

Cheers
Mark-----Original Message-----

Normal for EFI, agreed, but in my case, I found out that forcing the engine
in open loop smooths the idle significantly.
The car always seems to tun better after the battery has been disconnected.
At least for a little while…

The idle emissions failure was in in normal mode, closed loop though.

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Would this not mean that “default” values are working better than “learned”
values.

It probably means the default values are a bit rich. That’s how you get a smooth idle. But the ECU is gonna lean it up as soon as it can.

– Kirbert

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In reply to a message from Mark Eaton sent Mon 25 Jul 2016:

Mark:
Yes, this is how I interpret the results as well.
Somehow, the fuel map in the memory provides a better idle,
probably because as Kirby says, it is a bit rich, i.e., not
trimmed.

However, this will not be the reason for the emissions
failure at idle speed.
MAP is good. The line was recently reinforced with a new
silicone tubing.

Oil burning is a legit concern. I do have to add ca. 1 qt
between oil changes, but whether oil gets in the combustion
chamber via the breather or via worn valve seals remains to
be confirmed. I also cannot be sure that I burn that quart
of oil per 5000 miles since I have a small leak at the rear
of the sandwich plate.

Steve–
The original message included these comments:

Would this not mean that ‘‘default’’ values are working better than ‘‘learned’’
values.
Which suggests that either there is an input sensor tolerance problem (MAP,
coolant, air temp) or an output (injector) tolerance problem - (ie delayed
opening or closing or available voltage)
The fact that it is close would suggest that it is not a gross error, rather
a % out of whack type error. Thought. Has the MAP sensor hose got any fluid
in it? Does the MAP sensor hose hold vacuum? (ie is there a pin hole leak in
the sensor diaphragm)
Your car also has a part load air/oil breather system that feeds into the
rear of the intake manifold. Is it possible this is sucking in a small


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In reply to a message from mike waldron sent Mon 25 Jul 2016:

Mike:
I do not have the wide-band sensor and really doubt it can
do what you say it does. There only a handful (perhaps even
less) people that have successfully messed with the 36CU.
I’ve got two of them, one moded by Roger Bywater, and idle
is never perfect.

In any case, this does not explain the idle speed failure.
Something else is going on. The next paragraph confirms it.

So, last night I disconnected the battery, cleared the
memory and took the car for a re-test today. It passed.

Two years ago, the results were:
HC idle – 183 ppm
HC fast – 92 ppm
CO idle – 0.33%
CO fast – 0.49%

Today, the results are:
HC idle – 171 ppm
HC fast – 101 ppm
CO idle – 0.25%
CO fast – 0.46%

Noticed the higher idle numbers. The CO at idle when It
failed two weeks ago was over 1.2%, now is more than 4 times
lower.

I/WE WILL NEVER KNOW. If someone has an idea why the idle
test results are always worse than the 2500 rpm ones, please
chime in

Possible explanations for the success today:

  1. The test equipment was contaminated two weeks ago, now
    was in proper order (unlikely, but…)
  2. I drove the car 850 miles between then and now. Must have
    cleaned some gunk. Very likely old/bad fuel contributed
    too.
  3. There was an ignition system fault somewhere – plugs,
    rotor, wires, cap. (the misfire must have been gross and I
    would have noticed btw). The fault was corrected when I
    pulled/replaced the plugs and reseated the wires.
  4. Clearing the memory from the ECU did the trick. Perhaps
    there is a bad capacitor as suggested earlier, perhaps the
    idle trim does things to the mixture nobody can understand.
    In my view, this is the most likely reason for the pass
    today.

Many thanks to all that contributed. We will see again in
two years what happens.

Steve

PS I found a tuner shop near me, will take the car for a
test. They can measure O2 under load–
The original message included these comments:

It will let you know what your mixture truly is and even
let you ‘‘trim’’ where lambda is, so the ECU thinks it’s
operating at 14.7 but it’s really 13.5 or whatever you’d
like.


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In reply to a message from sbobev sent Tue 26 Jul 2016:

Steve,

Read up on ‘‘wideband uego o2 sensors’’. These are not a
narrow band sensor like what’s in your Jag, these are very
different.

Many people sell A/F ratio gauges that use narrow band O2
sensors and they are worthless.

The sensor in the link I sent you is a UEGO sensor that
has an output that simulates a narrow band sensor, this it
what would be plugged into the O2 sensor lead to your ECU
(you’d need two in your case).

You plug the sensor module into your computer and program
it with what AF ratio you want as stoichiometric. If you
tell it 14.7:1 it’s acts exactly the same as the narrow
band O2 sensor.

But; it you were to tell it 13.9:1 it will lie to your
ECU, making the ECU think it’s at 14.7:1 when in reality
it 13.9:1 (or whatever you want).

It has logging capabilities too.–
The original message included these comments:

I do not have the wide-band sensor and really doubt it can
do what you say it does. There only a handful (perhaps even


mike waldron
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In reply to a message from mike waldron sent Thu 28 Jul 2016:

You’ve done this on a V12 Jaguar XJS?
With the 36CU? Or the 16/26CU?

There is a guy that tunes Subaru STi’s near me.
He has done that many times, and claims to have built a
500HP car out of the 4-cyl 2.5L boxer.

When I talked to him, he said the equipment he uses cannot
do anything for the Jaguar (unless someone with the right
knowledge spends some time to figure out how the make the
obsolete technology in the 36CU work with the new gizmos
available today)

Steve–
The original message included these comments:

The sensor in the link I sent you is a UEGO sensor that
has an output that simulates a narrow band sensor, this it
what would be plugged into the O2 sensor lead to your ECU
(you’d need two in your case).
You plug the sensor module into your computer and program
it with what AF ratio you want as stoichiometric. If you
tell it 14.7:1 it’s acts exactly the same as the narrow
band O2 sensor.


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In reply to a message from sbobev sent Mon 25 Jul 2016:

withoug pulling and testing components you cannot be one
bundred percent sure that they are in good working order.a
visual inspecgion will tell you nothing as to their
condition save for a really bad capacitor which will show
actual case damage.I zuggest that you ask a radio tech for
an opinkon on that one.don’t take my word on it.failures in
storrage and filter caps are a regular occurrence
especially with caps produced around that time frame.a lot
oc sub standard components were flooding the market.
also…a scope will provide the much needed info you’re
looking for. az you have covered the other bases and you
know that the mixture is too rich where else would the
problem be other than faulty data.data for the innectors
comes from the ecu. like I said…its a pain and time
consuming but where the trail leads…
=dok=–
thewytchdoktor=v12 fun!/94 xjs 6 litre/ s=k.log w
Winchester Virginia, United States
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In reply to a message from wytchdoktor1 sent Thu 28 Jul 2016:

How do you know the mixture is too rich?
Mileage is good, the spark plugs are the right color…?

And why idle only?

Steve

PS I have an access to a scope, but do not know what else to
test. Everything that provides input to the ECU has been
pulled/checked/cleaned/replaced.–
The original message included these comments:

also…a scope will provide the much needed info you’re
looking for. az you have covered the other bases and you
know that the mixture is too rich where else would the
problem be other than faulty data.data for the innectors
comes from the ecu. like I said…its a pain and time
consuming but where the trail leads…


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In reply to a message from sbobev sent Thu 28 Jul 2016:

BTW Dok, how is your idle? Silky smooth?
Do you have emissions data on your car?

Steve–
The original message included these comments:

And why idle only?


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In reply to a message from sbobev sent Thu 28 Jul 2016:

Steve,

No I’ve not done this on a V-12 but it works with any
narrow-band O2 car… and don’t misunderstand what I’m
saying about this:

Using a wide-band O2 setup to TRIM your A/F Ratio can give
you a little better performance or fuel economy or help
you pass emissions test (like when you need to tweak HC
numbers a couple of percent), depending on your goal how
you program it (leaner or richer).

It will not, on it’s own, magically make your car a fire
breathing monster or replace the need to re-map the ECU
due to induction or other engine changes.

Now if you hook a wide-band to an ECU that can utilize
it’s data, like a custom Megasquirt system, you can do
amazing things, but that’s a whole different kettle of
fish!

I use wide-band O2 sensors to log mixture data and use
that data to re-map ECUs.

In my case I’ve got a fairly modified '59 MK-I and a
‘‘stock’’ '74 XJ-6 both with custom throttle bodies
(replacing the SU carbs) and distributor-less ignition
running on re-programed GM ECUs. I’ve got a similar setup
on a '46 ‘‘59A’’ Ford flathead, but with a regular
distributor.

With custom ECU tunes, the funny thing is; making them run
great at wide open throttle is pretty easy, but getting a
good idle is real tough!

Mike W–
The original message included these comments:

You’ve done this on a V12 Jaguar XJS?
With the 36CU? Or the 16/26CU?


mike waldron
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In reply to a message from mike waldron sent Thu 28 Jul 2016:

Thank you Mike, but I am afraid I don’t follow.
I don’t see how an amateur like me tweaking the ECU with a
wide-band O2 setup will accomplish anything.

The car runs very well. Has power, moves quickly, and has
normal fuel consumption at all conditions. I’ve already
accepted the fact that the idle will never perfect and I
don’t want to change that.

All I want is to be able to pass the tests – consistently -

  • and in this case understand why it didn’t. R. Bywater
    told me offline that a 6.0L V12 that is running properly
    should be able to meet emission standards even without the
    emissions equipment. Won’t happen for me… :-((

I am beginning to doubt the internals of my engine. Sadly,
anything more involved than changing the cam cover gaskets
is well beyond my abilities.

Steve–
The original message included these comments:

No I’ve not done this on a V-12 but it works with any
narrow-band O2 car… and don’t misunderstand what I’m


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Steve,

Personally, I think you have a lean misfire under closed loop (learnt
correction), not a too rich mixture.

The high HC thing with normal CO suggests a lean misfire. And if the default
settings are richer (as Kirby suggested) then your idle will smooth out
after battery disconnect.

At the end of the day, the only thing the testing is interested in is the
combustion within the cylinder chamber.

The question then becomes “What is happening to the combustion under idle
condition?”

I wonder what is happening to the ignition advance under idle conditions. Be
interesting to watch the advance after battery disconnect and after closed
loop running to see if they were different. There might be a stumble due to
too much advance being dialled in??

The other thing that “might” effect it is the fuel. Low octane burns faster
(apparently) and high octane slower. The burn rate helps define the ignition
point to achieve peak pressures at around 10°-14° ATDC. Could it be just a
case of using fresh fuel?

There are suggestions that old petrol:

  • Absorbs water (especially fuel containing ethanol)
  • Loses the volatile components through evaporation
  • Undergoes chemical changes that change its burning characteristics.

Didn’t you put fresh fuel in? Did that coincide with your passing the
emissions test?

Cheers
Mark

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