injector service off car. worth it ?

Built_Well > wrote:
>HLS wrote:
>> > Finally, people don't pay him $60 per used oil analysis for
>> > nothing, especially when you can get a used oil analysis from
>> > Blackstone-Labs for ~$23. But North America is about
>> > diversity, so you're welcome to your opinion :-) [Lol]
>> ==============
>> My unsolicited opinion is that used oil analysis is, for the most part,
>> a waste of money.
>========================
>
>I have to disagree here. Huge fleets and sober, bottom line
>minded trucking companies employ Used Oil Analysis on an
>ongoing basis to protect their costly engine investments.

You're both right.

IF you do used oil analysis on an ongoing basis and you watch trends, it
can give you valuable information about your engine, and it can also allow
you to optimize oil change intervals. On a long-haul truck this a big
deal and can result in substantial savings.

However, on an automobile that only takes four quarts of oil, it's cheaper
just to change the oil every 3,000 miles than to spend the money for regular
used oil analyses. Therefore it is a waste of money in this case.

And if you do a single analysis without doing it on a regular basis, you
have no way of knowing what the baseline value is or what the trends are,
and consequently that's a waste of money too.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

> And if you do a single analysis without doing it on a regular basis, you
> have no way of knowing what the baseline value is or what the trends are,
> and consequently that's a waste of money too.
> --scott
> --


I've had the oil checked, Blackstone, once. I was only interested in
finding any antifreeze. Everything else was good too but they told me
there was no antifreeze, which is the news I needed. If you have every
lost an engine due to antifreeze in the oil you would understand. I
then was able to track down the reason for a slow loose of the green
stuff. If there had been greenstuff in the oil I would need to return
this, brand new, rebuilt engine.

I don't opt for regularly doing this but after 2 years maybe it's time
for another check-up. 120K on this engine.

disston

Sorry for the double post but I forgot to mention that the original
problem, was it RT, rough idle, running?
I also recomend the MAF cleaning, check vacuum lines while at it, and
prolly a new airfilter. I now do the MAF cleaning everytime I change
the filter. I met a Toyota owner recently who told me he changed the
airfilter only every 80K. My impression was he was just cheap and
tried to explain the false economy of this. Got him thinking but not
sure if he did it.

First things first and then look into this more elaborate stuff. Car
talk lists, like this one, are a great source of info for the public.
But tell us what you did, or had done, recentlly. We will almost
always make you go through some basic stuff before advising the more
exspensive stuff. If not you would spend the 80 bucks to clean the
injectors, plus labour. And still have the same problem. If you don't
know when the last time was the MAF was cleaned, it is time to do it.
Oh, and you can do this yourself, maybe.

disston

"Scott Dorsey" > wrote in message
> You're both right.
>
> IF you do used oil analysis on an ongoing basis and you watch trends, it
> can give you valuable information about your engine, and it can also allow
> you to optimize oil change intervals. On a long-haul truck this a big
> deal and can result in substantial savings.
>
> However, on an automobile that only takes four quarts of oil, it's cheaper
> just to change the oil every 3,000 miles than to spend the money for
> regular
> used oil analyses. Therefore it is a waste of money in this case.
>
> And if you do a single analysis without doing it on a regular basis, you
> have no way of knowing what the baseline value is or what the trends are,
> and consequently that's a waste of money too.
> --scott

I dont disagree with that. Commercial fleets have different goals and
needs.

If there is a specific reason to do an oil analysis, for an individual, I
have no
issues with that. But if you are going to change your oil anyway over a
period
of 3000-7,000 miles, I feel it is money wasted that could have paid for the
oil change.

Built_Well wrote:
> HLS wrote:
>>> Finally, people don't pay him $60 per used oil analysis for
>>> nothing, especially when you can get a used oil analysis from
>>> Blackstone-Labs for ~$23. But North America is about
>>> diversity, so you're welcome to your opinion :-) [Lol]
>> ==============
>> My unsolicited opinion is that used oil analysis is, for the most part,
>> a waste of money.
> ========================
>
> I have to disagree here. Huge fleets and sober, bottom line
> minded trucking companies employ Used Oil Analysis on an
> ongoing basis to protect their costly engine investments.


Sheesh. For fleet operators its much less about protecting "costly
engine investments" than it is about saving the cost of replacing
thousands of gallons of oil before its absolutely necessary. Its one
thing to use oil analysis to predict when to change oil in machinery
that operates nearly continuously and carries a huge volume of oil per
machine, completely another thing to fool with it for the person who
owns one or two passenger cars, or even 5-6 collectible cars. Doing that
is the equivalent of driving a thumb-tack with a sledge hammer.

I met a Toyota owner recently who told me he changed the
> airfilter only every 80K. My impression was he was just cheap and
> tried to explain the false economy of this. .
----------------------------------------------------------------------------------------------------------------------
Food for thought,

Ohh this is just too good to let alone. I've been really busy in the
shop lately and even today had to fly through most of the responses
gaining just enough information to attempt to catch the highlights and
make some comments.

Remember this, "I'm not an engineer, just a technician that fixes the
things automotive engineers create"

A DIRTY AIR FILTER WILL NOT AFFECT NORMAL DRIVING FUEL ECONOMY ON
TODAY'S MAF (Mass Air Flow) sensored vehicles. There was a lot of
disscussion, but little spelled out for Jsteve to go and test to prove
the result. One of the tests that techs like myself use regularly when
in the process of diagnosing a vehicle performance issue is to
calculate the "reported VE" (Volumetric Efficiency) of the engine at
several WOT engine speeds. We use this calculation combined with fuel
trim data, (long and short term) to help analyze MAF sensor
performance, which is easily confirmed to be accurate or not based on
VE variance, combined with an associated fuel trim correction. In
short, if VE is low say 60-70%, and fuel trim is making a correction
to add fuel, that indicates unmeasured air is entering the engine. The
air could be pirate air getting in through a torn air inlet tube after
the MAF, or could be a faulty MAF. If VE calculates low, and there is
NO fuel trim correction, now we look for a mechanical reason that the
engine isn't breathing correctly. That could be a restricted exhaust,
engine mechanical issue, or in fact an air filter issue!

In all of my years as a technician (30+) the number of times that I
diagnosed a bad air filter as a performance problem accounts for only
a handful. Most of them were related to rodents storing food in what
appeared (to them) to be prime real estate. VBG. Almost every one of
the rest were related to an exhaust manifold or gasket failure, where
the thermostatic air cleaner system was picking up the leaking exhaust
gasses and coated the air filter with them.

The fact that an air filter that is truly dirty is a diagnoseable
condition without lifting the air filter lid and looking is important.
That also means that no matter how dirty an air filter looks when
inspected, proper testing can prove beyond any doubt as to whether it
actually needs replacement.

From this point here is your test Jsteve. If you don't have access to
this formula e-mail me and I can send you a version of it. You will
need a good scan tool that will give you data as fast as possible. The
faster that the data scrolls, the more accurate that the RPM, VS the
Airflow reading in grams per second will be.

Go ahead and take your first VE measurement with whatever air filter
you have in the car. Take note of long term and short term fuel trims
under normal driving conditions at varying vehicle speeds, and
throttle openings. Also take note of the calculated spark timing, and
if there is spark retard occuring from a knock sensor input. (MAF
vehicles use the MAF to assist in not only fuel mapping but spark
timing mapping as well) Then take the air filter out for testing
purposes and repeat the test! Make sure that your air inlet assembly
is clean of any deris etc.

Now the fun starts. Take a can of spray paint and a cheap replacement
air filter. Paint 1/4 of the filter to completely block it of airflow.
Install the filter after it dries and re-test. Use an enamel paint to
make sure it seals the filter. If you have access to an O.E. level
scan tool such as an IDS on a ford you could go ahead and drive some
type of a course and measure actual fuel economy. In fact backing up
you could have started out this test that way!

Now paint another 25% of the filter. You now know without question
that you have a filter that is 50% restricted, right? See how this
measures out now.

Now go another 25%, so your filter is definately 75% restricted. Do
you think you have ever driven a car with a filter that was THAT
dirty?

You now have a filter that only 25% of it has airflow. Paint half of
what is left and repeat the test, with only 12.5% of the filter
allowing airflow. Depending on circumstances I'll wager this to be the
first time you see a significant difference in MAX VE. However, I'll
also wager you will not yet see a loss of fuel economy, and you could
in fact lend this car to another person and they could drive it and
not notice anything wrong!

The reason for all of this is gasoline engines are of course an air
pump. The speed of the engine is set by the airflow that it recieves,
and it does NOT matter where the restriction to that airflow is. The
greatest restriction will always be the limiting factor. If you would
take my Ford Explorer and restrict the filter to about 12.5% area, you
would still have 80% of the cross-sectional area of the throttle body
and therefore almost no noted restriction.

Now one of the other responses was asking about variable cam timing.
We should start a thread specifically about that, instead of doing it
here. Suffice it to say at the moment that scavenging of the cylinder
gasses is only the tip of the iceberg. The engines actually
effectively control displacement, eliminate the need for EGR, since
the cam can do that job, and much more!
-----------------------------------------------------------------------
Excellent thread. Here's my low-tech anecdote that supports the
conclusion reached by the group. I've a Toyota Landcruiser that I use
to haul the family to our summer house on a lake over 200 miles away.
It's stored over the winter. I always fill up at the same two gas
stations at either end. I'm particular with logging MPG, which has
averaged 13.4 MPG over a couple of years. Before putting it away two
winters ago, I changed oil & all filters (including air) Last summer,
brought it out, and it seemed a bit sluggish on it's first trip of the
summer. Checked MPG; showed 13.6 on the way down, 13.5 on the way
back. Same thing on the next trip. Finally got around to sniffing
out the source of the sluggish operation. Opened up air filter box,
and found it virtually plugged with a huge rodent nest. From the
density of the nest, I struggled to understand how the engine produced
as much power as it did. However, I rechecked my fuel log, and could
not discern any noticeable change in fuel economy, with an almost
totally plugged filter. Luckily, the mice did not chew through the
filter, so nothing nasty made it's way into the engine.

http://www.eng-tips.com/viewthread.c...=214125&page=3

wrote:

>
> A DIRTY AIR FILTER WILL NOT AFFECT NORMAL DRIVING FUEL ECONOMY ON
> TODAY'S MAF (Mass Air Flow) sensored vehicles.

Yes and no. If the MAF were the ONLY sensor that affected mixture, then
the above would be true. But the actual fact is that mixture is set by a
combination of throttle position, MAF, O2 sensor, and other parameters.
When the air filter gets extremely dirty, the throttle will have to be
cracked open more than "normal" to get a particular power from the
engine, so the MAF and throttle position sensors will "disagree"
slightly, meaning that the calculations the computer does to determine
the fuel injector duty cycle may be slightly skewed.

So there IS an effect, but its probably too small to measure in
real-world conditions where changing temperature and humidity (among
other things) would easily mask the fuel penalty.

Of course the dirty air filter will reduce peak power available, and it
will still cause the mixture to be significantly rich during open-loop
operation where the MAF sensor is ignored.

And speed-density systems (MAP sensor instead of MAF) will be affected
differently than MAF systems.

"Steve" > wrote in message
...
> wrote:
>
>>
>> A DIRTY AIR FILTER WILL NOT AFFECT NORMAL DRIVING FUEL ECONOMY ON
>> TODAY'S MAF (Mass Air Flow) sensored vehicles.
>
> Yes and no. If the MAF were the ONLY sensor that affected mixture, then
> the above would be true. But the actual fact is that mixture is set by a
> combination of throttle position, MAF, O2 sensor, and other parameters.
> When the air filter gets extremely dirty, the throttle will have to be
> cracked open more than "normal" to get a particular power from the engine,
> so the MAF and throttle position sensors will "disagree" slightly, meaning
> that the calculations the computer does to determine the fuel injector
> duty cycle may be slightly skewed.

You are ignoring the fact that the throttle position sensor is a very gross
indicator. It doesn't supply the fine sort of data that would be needed to
cause the effects you are suggesting. Take a look at a shop manual for a
Toyota and you'll see that the acceptable range of response for a particualr
throttle opening is more than +/- 5%. This is a far greater effect than any
slight change in air flow at part throttle attributable to "normal" air
filter restriction. Furthermore the PCM learns paramters to compenstate for
gradual/minor changes such as air filters loading up. If a filter is so bad
that it affect fuel economy significantly, you will get a mil indication.

> So there IS an effect, but its probably too small to measure in real-world
> conditions where changing temperature and humidity (among other things)
> would easily mask the fuel penalty.

It will be so small that you won't be able to measure it with instruments
either. It will be well below the noise level in most cases. I won't say a
dirty air filter will never effect fuel economy, but it will be an unusal
case if it does.

> Of course the dirty air filter will reduce peak power available, and it
> will still cause the mixture to be significantly rich during open-loop
> operation where the MAF sensor is ignored.

The MAF sensor is not ignored during open loop mode. The O2 sensor is. And
fuel trim learned during closed loop mode will modify the open loop mode
parameters so that even during open loop mode, the effect on fuel economy
will be trivial. I do agree a dirty air filter will affect maximum power.

> And speed-density systems (MAP sensor instead of MAF) will be affected
> differently than MAF systems.

True, but again, the PCM modifies the operating parameters based on closed
loop operation. A "normally" dirty air filter won't have asignificant effect
on the fuel economy of speed density systems either, at least after they
have operated long enough to learn the proper fuel trims. Speed density
systems primarily calculate air intake using rpm and manifold pressure, not
the throttle position sensor. If you look at performance curves for throttle
position sensors, you'll see that they simply not capable of providing the
sort of detailed precise data needed to determine the amount of fuel to be
injected. TPS are used to indicate gross changes in the position of the
throttle so the fuel inection can reacted to changes. Think of them acting
in place of an accelerator pump or a dashpot, not a metering device. The
most import positions are closed (for idle control) and wide open. There are
some throttle position sensors that only indicate idle and full throttle,
with no indications in between. Most provide a signal that varies with
throttle angle, but it is usually a linear relation ship, while the air flow
through the throttle bore does not vary in a linear measure with throttle
angle.

http://www.bosch.com.au/content/lang...leposition.pdf

Ed

Built_Well > wrote in news:130be0b0-57bb-
:

>
> Tegger wrote:
>>
>> I think Terry Dyson is overrated and thinks he knows more than
>> he actually does.
> ========
>
> [Chuckle] Well, I think Mr. Terry Dyson of Dyson Analysis is
> a renowned tribologist with decades of experience who analyzes
> UOAs on a daily basis. He can see, for example, the effects of
> different brands of gasoline on engines that have
> fuel dilution blow-by problems, piston ring problems, etc.



He may know oil, but he has very little idea of what happens inside a
gasoline engine that puts in the oil what he finds there.

Basically, he can tell you what's in the oil, but he can't tell you why
it's there. He may think he can, but he can't.


--
Tegger

On Thu, 19 Jun 2008 05:04:00 -0700, Built_Well wrote:

>> Perhaps TOO many! I get horrible mileage with V-Power, and since I get it
>> in VT it's 'real' gas.
>>
>> I get better mileage with 2nd tier E-10 Premium than I do with V-Power!
> ==============
>
> Why don't you elaborate on this, Hachi. Give us some
> concrete mileage numbers. Interesting :-)


OK: 27-29MPG with the Mazda running Ethanol-laced gas, 23-25 with 'real'
gas from Vermont.

29-31 MPG with the Scion on E-10, 27 with 'real' gas.

Supra? Can't tell. Speedo's broken. Right foot works well. But real gas
'disappears' faster than E-10.