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87 5th Avenue Emission Problems



 
 
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  #11  
Old May 28th 05, 08:26 PM
Daniel J. Stern
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On Sat, 28 May 2005, Comboverfish wrote:

> > Those are pretty standard state limits for an '87 car, and he's
> > flunking them very, very badly.

>
> No doubt. I'd go after rich-running culprits first; gross causes like
> air bleed blockage in the carb, choke closed, etc...


Air bleed, perhaps, but a stuck-closed choke doesn't jive with 0.16% CO
and 1220ppm NOx under load.

> The converter may be toast already having to deal with this kind of
> overload (at idle).


Very possibly so. I can't remember if they were still farting around with
multiple converters in '87.

> > He might be on the phone awhile. There weren't all that many techs who
> > could do a good job with these Lean Burn systems when they were
> > current and new!

>
> That's a challenge I like, but the work would be "by the hour" for sure.


Well, that's part of the challenge: matching a tech able *and* willing to
put in the time with an owner able *and* willing to pay him to do so!


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  #12  
Old May 28th 05, 09:12 PM
aarcuda69062
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In article
ich.edu>,
"Daniel J. Stern" > wrote:

> On Sat, 28 May 2005, aarcuda69062 wrote:
>
> > > HC: 504ppm (limit 300ppm) FAIL
> > > CO: 6.76% (limit 1.5%) FAIL
> > > NO: N/A
> > >
> > > Still looks like lean misfire under load, possibly inoperative or clogged
> > > EGR system, possibly dead catalytic converter(s), possibly inoperative
> > > Oxygen sensor, possibly malfunctioning carburetor, possibly malfunctioning
> > > Lean Burn computer...

> >
> > Lean misfire with 6.7% CO and attendant 504 ppm HC?

>
> Lean misfire *under load*. The 6.7% CO and 504ppm HC are idle readings.


True enough... your text reply followed the idle reading though.
  #13  
Old May 28th 05, 11:30 PM
Comboverfish
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Daniel J. Stern wrote:

> Air bleed, perhaps, but a stuck-closed choke doesn't jive with 0.16% CO
> and 1220ppm NOx under load.


That's the problem here... there are surely multiple problems which
will all need to be corrected before all three gasses are within the
allowable limits.

We're theory ****ing without hands-on testing. Great, now I just typed
'****ing' and 'hands-on' in the same sentence.

Toyota MDT in MO

  #14  
Old May 29th 05, 01:15 AM
Mr. Minnow
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I'm From Canada (ONT.) And I forgot to mention a stubborn oil leak from your
guess is as good as mine(I just can't pin point it.) I know it's not the EGR
or Cat Con (Replaced in '01 car drove it to Nov 2002 then it sat for 2003 &
2004). I don't know if the oxygen sensor was replaced but more than likely
it was.

Thanks Mr. Minnow


  #15  
Old May 29th 05, 02:20 AM
Daniel J. Stern
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On Sat, 28 May 2005, Mr. Minnow wrote:

> I'm From Canada (ONT.) And I forgot to mention a stubborn oil leak from
> your guess is as good as mine(I just can't pin point it.) I know it's
> not the EGR or Cat Con (Replaced in '01 car drove it to Nov 2002 then it
> sat for 2003 & 2004). I don't know if the oxygen sensor was replaced but
> more than likely it was.


You really can't say the EGR and catcon are good just because they were
replaced. With your HC as high as it is, the catcon could easily be
cooked. And the EGR valve is only one part of the system; the crossover
passage and ports (in the intake manifold and the heads, respectively)
could well be clogged with carbon.

Don't know where in Ontario you are, but I can recommend a couple of good
shops in the Toronto area. Canadian Tire does not count as a good shop.
  #16  
Old May 31st 05, 08:35 PM
Steve
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wrote:
> On Sat, 28 May 2005 00:48:25 -0400, "Daniel J. Stern"
> > wrote:
>
>
>>On Fri, 27 May 2005, Mr. Minnow wrote:
>>
>>
>>>I took my car(87 5th Ave with a 318(5.2L) v8) in for an emission test and it
>>>failed miserably
>>>
>>>Here are the results:

>>
>>It's *very* hard to read your results -- the tabulation didn't come out as
>>you tried to make it do -- but it looks to me as if your results a
>>
>>HC: 197ppm (limit 83ppm, FAIL)
>>CO: 0.16% (limit 0.46%, PASS)
>>NOx: 1220ppm (limit 893ppm, FAIL)
>>
>>Your CO is about 1/3 of the allowable limit, and is an excellent reading
>>for a carbureted car -- but your HCs are more than double the allowed
>>limit, and your NOx is 1/3 higher than allowed. This combination of
>>results suggests your engine is running so lean that it is misfiring.
>>Those cylinders that do fire produce a great deal of NOx due to the lean
>>mixture, while those that do not fire produce a great deal of HC due to
>>noncombustion.
>>
>>(These '85-'89 civilian M-body cars with the Holley 2bbl don't generally
>>run very well in stock form, even when everything is set by the book. Lean
>>surge under steady throttle is the rule, rather than the exception. Not
>>that this helps you -- just saying.)
>>
>>So, what's causing your misfiring? Could be any number of things. A faulty
>>Oxygen sensor in the driver side exhaust manifold (how long since you
>>replaced it?). A faulty carburetor, a faulty Lean Burn computer, a plugged
>>fuel filter...it might not even be a lean misfire at all; your readings
>>could also be caused by the reduction portion of the exhaust catalyst
>>system having reached the end of its life, resulting in very high NOx
>>tailpipe readings and insufficient free Oxygen in the exhaust stream to
>>allow the oxidation section of the catalyst to clean up the HC.
>>
>>Time for some systematic diagnosis by someone who has considerable
>>experience with the carbureted Mopars of the mid '70s through late '80s.
>>Just throwing parts at it will get very expensive long before the problem
>>is solved.
>>
>>DS

>
> Is this vehicle still 100% stock, or has somebody screwed around with
> the lean-burn?I've seen these engines "converted" to standard carbs
> (remove the lean-burn) not have a chance of passing E-Test
>
> Otherwise,Mr Stern has pretty well covered it.


Actually, a converted car WITH a working set of catalysts and correctly
tuned SHOULD pass with flying colors. But what usually happens is that
someone replaces the ignition system, disconnects the lean-burn
computer, and leaves the lean-burn carb in place. That doesn't work so
good, because the lean-burn carb NEEDS computer control to work right.

There are two ways to do the conversion:

1) replace both the carb AND the ignition and do away with the computer,

2) Replace the ignition, but let the computer continue to control the
carb. It doesn't "know" that its not still controlling the ignition, and
will merrily hum along (assuming that the computer is working, the O2
sensor is working, and the carburetor's VDC solenoid is working.)

 




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