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

[Alexander Ishii (alexishii]

> You wrote <<I think all the time, but it is easier to be sure the problem is
> there when the engine is hot, and idling at its "hot" rate.>>
> 
> That might be telling us that when the engine is cold and somewhat richer,
> it might be overcoming a lean situation often caused by vacuum leaks or
> other problems.

You know, that is an interesting speculation.

Tomorrow I'll have to try and start the car from stone-cold and see what I
can hear.

The reason I said it was easier to be sure at hot-idle is that the 2k-rpm
cold idle makes such a din that it tends to drown-out other noise...

> BTW, I am familiar with the "Wiggle Test" and have used it myself - but it's
> not very effective I fear.

I actually tend to agree with that, but when it is all you have... :)

> Perhaps it's possible for you to remove the
> accessible vac hoses and snip a 1/4" off the end and replace it?   Naturally
> it depends on the length available.   My experience has been the ends of the
> hoses begin to self-destruct with  tiny cracks extending from the hose end
> back toward the hose.   It's also possible there are vacuum connections you
> cannot see and/or reach, so checking them is not practical.   Perhaps one of
> tem is leaking/loose?

I'm planning to change the injectors and redo all the hoses while I'm in
there...

> Good luck!  Merry Christmas!

Many thanks!

    -- Alex

> -----Original Message-----
> From: Alexander Ishii
> Sent: Thursday, December 23, 2010 2:02 PM
> To: l02turner [at] comcast.net
> Cc: The FerrariList
> Subject: Re: [Ferrari] 308 QV emissions failure and possible misfire
> 
> 
> Hi Larry,
> 
>>     It's often the most simple of things that cause problems - look
>> closely
>> at all hoses - inspecting for looks connections, damaged hose ends
>> (usually
>> from heat), damaged gaskets or loose flanges of all sorts.
> 
> Have checked to the extent that I can without disassembly, and did not find
> anything obvious.
> 
>>     BTW - Did the problem start after the plugs and wires were replaced?
> 
> No, the problem predates the plugs and wires.
> 
>> Does it do it more when cold?  Hot?  All the time?
> 
> I think all the time, but it is easier to be sure the problem is there when
> the engine is hot, and idling at its "hot" rate.
> 
>     --  Alex
> 
>> -----Original Message-----
>> From: Alexander Ishii
>> Sent: Thursday, December 23, 2010 10:58 AM
>> To: Larry Turner
>> Cc: The FerrariList
>> 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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