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

[l02turner (l02turner]

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.

At least that's one possibility.

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

Good luck!  Merry Christmas!
LarryT

-----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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