[DML] Re: Couple Questions- Coolant System & Idle

["endotex23" <endotex23@xxxxxxxxx>]

--- In dmcnews@xxxxxxxxxxxxxxx, "David Teitelbaum" <jtrealty@xxxx>
wrote:
> 
> 
> As I see it you have 2 control loops, the idle speed control and the
> Lambda control.<

You have 3. The CI system is a closed loop unto itself, though
mechanical/hydraulic in nature. As I said earlier there are procedures
for identifying the cause of unstable idle and it helps a great deal
if you divide them into hot or cold. Only by doing this can you track
it down without wasting lots of time. It beats struggling with each
loop while they're in action, especially when they may not be cause in
the first place. The bottom line is idle hunting is almost always
mixture related (note I said almost always, there are other causes)
and it's not normal. Those who say it is do so only because they
believe it to be inherent in the design. It's not. It can be fussy due
to the factors you mentioned but it's not something one has to live
with.

As you pointed out, the mixture screw is not a cure-all. Nor does it
really control mixture above idle anyway. It must be set correctly for
many reasons though, one of which is for proper functioning of the
lambda loop. Get it wrong and you'll be killing the effciency of your
cat. That's a good thing if you can pull it off and aren't subject to
emissions testing. As Martin pointed out, a D at around 2-3% CO is a
sweet ride.

Everything else you point out is pretty much true and that's the
beauty of a modern PCU versus the K Jet. No matter what they have
people need to remember there are 6 little engines in there, not one.
Every do a power balance test? It's a commom diag procedure with EFI
and with a little creativity can be done on a K Jet too.

For the guy who is getting poor fuel economy: Did you emissions test
the car? If so did it pass? What are the numbers? EGA will tell you
much about the quality of combustion occuring in your engine,
especially when done upstream of the cat. Take the car to a smog
station or any good shop and have them run a engine out (pre-cat) EGA
on it. If it comes out good it'll narrow the cause for poor fuel
ecomony to very few things.

Don't forget other, non-powerlant, issues like rolling resistance,
speedo error, ect. Remember, there are two variables in the
miles/gallon equation 

Greg

 








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