Ferrari Mailing List: Re: 308 QV emissions failure and possible misfire

[Alexander Ishii (alexishii]

Hi Doug,

> Ahhh Alex - the ever wonderful world of CIS, the constant injection system.
> VERY temperamental to air leaks.

Yup, I've looked over all the leak points that I can inspect without pulling
the major plumbing bits, and found nothing that looked suspicious (or that
had an effect on the idling when "wiggled").  My plan is to replace all the
hoses when I take the thing apart, just for good measure.

> Especially at the boot area.  The pop you
> hear may be a misfire fired off in the cat (shudder)

I also hope this is not the case.  I don't think it is, as the source of the
"pop" seems to be close to the engine, rather than back where the cat is.

> but most likely it is a
> lean mixture misfire spit back.

This certainly would mesh with the engine-temp issue.

> Do you have a method to check CO?  These systems are set on fuel pressure
> and CO.
> 
> What is failing on your smog report?  HC, CO, NOx (do you test for that?
> Needs a dyne to do it or the test equipment is shoved in your passenger seat
> and your car is driven about - yes, they had that at one time)
> 
> Get me your readings - its like the engines blood test.

At idle the results are:

HC ppm  270     (pass is 220)
CO%     0.51    (pass is 1.2)
CO2%    14.6
O2%     0.5

At high idle the results are:
HC ppm  100     (pass is 220)
CO%     0.52    (pass is 1.2)
CO2%    14.5
O2%     0.3

Any thoughts would be greatly appreciated.

     Cheers,
     Alex

> ----- Original Message -----
> From: "Alexander Ishii" <alexishii [at] mindspring.com>
> To: "DOUG" <dnt [at] dock.net>
> Cc: "The FerrariList" <ferrari [at] ferrarilist.com>
> Sent: Thursday, December 23, 2010 7:58 AM
> Subject: [Ferrari] 308 QV emissions failure and possible misfire
> 
> 
>> 
>> Hi All,
>> 
>> So my 84 QV has been stubbornly failing emissions (in NJ), and after some
>> repeated assertions by my usual mechanic that "all seems to be well", I've
>> found myself having to try and figure out the problem myself.
>> 
>> At the moment, the car is not idling right in my mind (despite what my
>> mechanic says).  For one, the idle speeds "hunts" a bit; not enough to be
>> seen on the tach, but enough to be felt as a slight change in the
>> vibration
>> frequency of the engine.  Second, every couple of seconds one gets a
>> just-audible muffled "pop" sound from the engine, accompanied by a slight
>> puff of extra exhaust out of the tail pipes (no sound out of the air
>> intake
>> system).  Also, the car is running sort of on the hot side (coolant temp
>> "idles" at 195).
>> 
>> Plugs and wires were changed not long ago, but other than that, nothing
>> much
>> has required much tinkering in many years.
>> 
>> The "pop" has me thinking than one-or-more of the cylinders is
>> intermittently misfiring and dumping some un-burnt fuel into the exhaust
>> manifold (where it is igniting and "popping").  Given the "every couple of
>> seconds" nature of the problem, however, I have little doubt that all the
>> sparks will look fine when I try the usual tests.  Anyone have any
>> suggestions for how I might try and zero-in on the faulty system (short of
>> swapping-out every part one-by-one until the issue goes away)?
>> 
>> Also, it has also occurred to me that the problem might be that the
>> injectors are not atomizing properly, and leading to an complete burn (in
>> turn leading to exhaust manifold ignition of the leftover fuel).  Has
>> anyone
>> seen symptoms like the above be remedied with replacement of the
>> injectors?
>> 
>> All thoughts/opinions/experiences would be appreciatively accepted.
>> 
>>    Cheers,
>>    Alex
>> 
>> 
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>