MAF meters and open-loop.

[Daniel Houlton]

Chris Conlon wrote:
> 
> At 08:51 AM 2/24/99 -0700, Daniel Houlton wrote:
> 
> >LM3914) with the 10 LEDs.  When driving under boost (about 5 or 6
> >psi) if I keep the throttle under about 3/4, the meter shows a
> >slightly rich condition.  But somewhere just after 3/4 throttle,
> >the meter drops completely off (full lean).  
> 
> Without going into a lot more detail...
> Partial/slight/intermittent rich misfire?

Can't tell if there's a misfire.  Power doesn't change at all and
it doesn't stumble or cough.

> Timing very retarded, due to WOT switch or knock sensor?

No knock sensor so it can't be that.  Timing isn't retarded at all 
and I'm pretty sure that the WOT doesn't cause it to do so.  I will 
need to check the manual on that one to make sure.


> 
> Other possibly helpful diagnostic details:
> Does the engine still make good power under this condition?

Yup, power doesn't drop off.  Only indication it get is the A/F meter.

> Do you get detonation / do you have a knock sensor?

No detonation or pinging that I can hear of feel.  No knock sensor.


> Does your turbo manifold glow red after a hard run?

Hmm.  Don't know.  I will have to check this one.  The manifold and turbine
scroll housing are ceramic coated.  Will they still glow like this?  Also,
the down pipe out of the turbine is a double wall type all the way to the 
cat convertor so that won't really be obvious if it is glowing.

> 
>    Chris C.

Thanks for the ideas.  I'll check after dark to see if the manifold is
glowing at all.  Any more?


thanks
--Dan