[Diy_efi] Smog pump and emissions testing question...

[Brian Renegar]

Ok, I see what you are saying about the air injection holes being 
clogged.  But I have Edelbrock heads, which do have the thermactor holes, 
and have been off of the motor several times, including hot tanked.  So I 
would think that the holes should be clear in my case.  The only visual 
inspection they do is for the cats.  They do not open the hood, so I don't 
have to worry about "why is that hose running there instead of here" kind 
of questions.  BTW, I'm probably going to be using my factory H-pipe for 
the emissions test.  Would it still be better to route the smog pump to the 
cats, or instead run it up to the cylinder heads?

Also, the test is not "steady state", as you say.  They DO vary the load, 
mph, as in a normal driving situation.  Everything from idle, low speed 
cruise, mild to moderate acceleration (as in freeway entrance ramps), to 
highway speed cruise is tested.  I have taken my Jeep through the test, and 
you can watch the various stages it goes through.  We went through 
everything, all the ways up to 55 mph.  What I'm worried about is the 
people not knowing how to drive on the dyno.  As I said, a friend took his 
through emissions and failed.  Most of that was due to the emissions tech 
not knowing when to shift the car.  As an acceleration period came up, he 
would up shift to the next gear, and then have to floor the gas to keep the 
wheel speed in the increasing limits.  Obviously at that point emissions 
were out the window, and he tried to explain that to them, but they 
wouldn't listen.  If I tune the car to just run at 14.7:1 for all 
conditions and that situation comes up, I could have a blown up 
engine!  I'm almost tempted to put a throttle stop in place to keep them 
from giving it too much gas so that doesn't happen!

Brian


>On Mon, Apr 28, 2003 at 03:12:23PM -0400, Brian Renegar wrote:
> > I've got emissions testing coming up for my 91 Mustang.  Here in Maryland,
> > they do the "road dyno" testing now.  I'm trying to prepare and have
> > everything tuned properly so it will pass.  The engine is fully built with
> > twin turbos.  The thing I'm worried about the most is the cam, which is a
> > Motorsport F303.  This particular cam is not "emissions legal", however
> > that doesn't mean it won't pass.  I've passed with another Motorpsort cam
> > (E303), which has more overlap than the F cam does.  The F cam, however,
> > has more lift (.512 versus .498) and more duration (I forget those specs),
> > and I don't know how that affects emissions.
>
>The emissions will rely heavily on ignition timing.  The Ford computer runs
>closed loop at idle once warmed up.  The only thing to muck with then is the
>timing.  Less timing reduces emissions.  I had to do this on my Mustang when
>I got it smogged here in CA.
>
> >
> > So anyways, the other issue is that I have removed the smog pump and 
> all of
> > it's associated tubing and vacuum solenoids.  I was planning on just
> > installing the pump and running the hose directly to the exhaust, since
> > that's what the computer's strategy would be during warm
> > operation.  However, I just had an interesting conversation with a
> > friend.  He suggested instead of running the tube down to the exhaust
> > H-pipe, to run it to the back of the cylinder heads (which is the other
> > location the factory setup runs the smog pump to).  He said that the 
> longer
> > the exhaust gasses are in contact with the fresh air being pumped in, the
> > more residual combustion (I guess you could say) will occur, and the lower
> > the emissions.
>
>First, the banjo air injection on the heads is plugged up on most vehicles.
>Carbon buildup impacts the tube and plugs it up, so this does nothing.  It may
>visually pass, but past the first 3/4 of 100k, it definitely doesn't work.
>
>Okay, the strategy as I know it is this:  At startup air is injected into the
>head.  Once the cats are sufficiently warm (probably a timer), the pump then
>injects into the cats.  Ford used dual 2 way cats on the stock H pipe, their
>injection didn't do much more than further the combustion.  Most aftermarket
>dual cat pipes use 3 way cats.  This is where air injection actually does 
>something
>useful.  In a 3 way cat the air is injected between the intaks an exhaust
>stages and causes a further catalyzing process.  These cats will produce
>nitrogen and water, where 2 way cats do not.  This beneficial.
>
>As for the pump, if the hose routing is physically in the way, get the 93
>Cobra electric pump.  These lived down on the passenger side wheel well.
>Now route the hoses to the stock valves, but in convenient locations.
>
>Any intelligent (this is important) SMOG guy will inspect the system and ask
>questions.  You must be able to explain how the system works and where the 
>parts
>are from.  I do not advocate disabling of emissions control devices.  I want
>to have fun, but I don't want to help destroy the environment at the same 
>time.
>
> >
> > It sounds like a good idea to me.  But I'd love to hear what others 
> have to
> > say about this too.  BTW, I have a programmable chip with data logging
> > capability, so I will be able to decrease the timing, and set all fuel
> > trims to 14.7:1.  It still worries me some though, that I have forced
> > induction.  If the dyno operator decides to give it too much gas, I will
> > HAVE to add some fuel, or risk blowing the motor up.  And from what I've
>
>Again, the Ford computer runs closed loop until: WOT or "high load".  You
>can adjust the high load timer to a higher number or run the stock 2 seconds.
>
>WOT is exempt from SMOG testing.  He will test your vehicle at a given speed
>on the dyno.  Likely to be 40-45MPH in 4th gear.  If you have the proper gear
>ratios (not 4.10 or higher), this is about 2000RPM.  He may test your vehicle
>at 2500RPM instead.  The Ford EGR code doesn't open EGR until 40MPH, so that's
>a magic number.  Ford didn't add any lean-cruise until much later, so it's
>going to be closed loop for the entire test.
>
> > seen, and heard by others, the dyno operators here know absolutely nothing
> > about how to properly run an engine on the dyno.  Things like shifting too
> > soon, and then having to floor the gas in order to keep the rpm where it's
> > supposed to be during the test!
>
>Well, they can only test at steady state throttle and speed.  Your turbo motor
>shouldn't have any problems with keeping steady.
>
> >
> > Brian
> >
>
>I've got an '89 Mustang GT, 306 with TFS TW heads, E303 cam, TFS street 
>intake,
>forged pistons, roller rockers, 24lb injectors, and it passed smog in CA 
>without
>having to pay the tax (ya know, here's $200 bucks, make it pass).
>
>--Perry
>
>--
>Perry Harrington                        Data Acquisition & 
>Instrumentation, Inc
>perry at dainst dot com                                 http://www.dainst.com/
>
>Those who would give up essential liberty to purchase a little temporary 
>safety
>deserve neither liberty or safety. Nor, are they likely to end up with either.
>                              -- Benjamin Franklin
>
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