80tq: Opinions wanted

[Joshua Van Tol]

Javad, is it possible the ECU is fueling improperly? I know you said
something about watching the mixture, but  it's possible that if it
went rich enough, fast enough (as in an overflow in an injector pulse
width calculation) that you'd have so many misfires that the mixture
might read somewhat normal? The puffs of black smoke sound suspicious
to me. Do you have a wideband O2 sensor in that beast? If so, you might
be able to datalog it, and see what's happening better. I'd be inclined
to think the mechanical fault in the head gasket is a separate issue.

On Wednesday, February 5, 2003, at 07:47  PM, JShadzi at aol.com wrote:

> See, that's the thing, I don't believe any coolant is coming back in
> the combustion chamber, on the track the only thing anyone ever
> mentioned was that they'd see a puff of black smoke here and there
> (like a rich condition, which would make sense if the boost was being
> blown into the coolant in one comb. chamber), no one has ever illuded
> to any coolant looking smoke, all the spark plugs look good, nice dark
> crispy tint to them.  I think that the leak is only caused by a
> *certain* amount of pressure, and that's why its aggrivated at certain
> boost pressures and above.  Like you say, usually head gasket failure
> is more catastrophic, that's why I'm kinda stumped, its done this very
> consistently the last 3 track events, I'm just waiting the for the
> thing to blow once and for all.
>
> Any BTDT out there?
>
> Javad
>
>> That was my first thought as well, but I didn't want to say it becasue
>> I've not seen a "small" headgasket leak before..
>>
>>> but could this cause the rpm cutout
>>> as described?
>>
>> If the leak stays open, yes. On the power stroke excess pressure goes
>> into
>> the cooling system- on the intake stroke coolant could be drawn into
>> the
>> cylinder through the same leak.  That would lead to the same sort of
>> spark
>> problem that you'd see if you over-did water injection, which would
>> first
>> show up as a high RPM, high boost cutout.
>>
>> I've seen something like this with a bad headgasket problem and warped
>> head- liquid coolant came out the exhaust- but if it were a "small"
>> headgasket problem it could look like this.
>