MAF meters and open-loop.

[Daniel Houlton]

soren wrote:
> 
> >> Have you saturated the meter?
> >>
> >
> >Haven't been monitoring the output of the meter, but now that
> >you mention it, that very well could be it.
>
> Are you using the meter from your 2.6 NA or the one from the 4ZC1-T that the 
> turbo and stuff came off of (I am guessing here but pretty sure that's the 
> only turbo stuff that will fit easily on your 2.6)?  The mass air meter from
> the 2.0L 4CZ1-T saturates around 10 psi of boost (on a 2 liter engine in an   
> Impulse).

Yeah the turbo is off the 4ZC1-T Impulse ('88) and I'm not using the knock
sensor or the stepper motor boost controller thingie off of it either.  The
MAF on the Impulse is a rather small one.  About 40mm dia with a smaller
(~5mm?) bypass where the hot wire is.  On mine, it's much larger.  About 74mm
i.d. with a small vertical post up through the middle that houses the hot
wire.  So, it has easily over 3 times the cross-sectional area.  I'm surprised
that the MAF can be the problem.  This thing is huge for such a little
engine and it's in line with the sizes of aftermarket MAFs I've seen that
are intended for v8 owners upgrade to.  The throttle body too, BTW, is
larger as well.  About 70mm I think and round instead of the smaller oval
of the Impulse.

> 
> >> 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.
>
>     The 4CZ1-T has a knock sensor on the block but it is used only for boost
> control, no timing effects as far as I know.  If you didn't use the TCS
> solenoid and controller off the donor Impulse (still basing my reply on the
> guess about the donor vehicle) the knock sensor shouldn't be an issue.  The
> WOT switch does not retard spark in this application.
>
> I just set up an additional injector to trigger under boost (right at the
> pressure where it used to go lean) and WOT on my Impulse, it should allow
> more boost without screwing with the MAF signal.

I've considered this as well, but I'd much prefer an AIC to actually meter
a measured amount of fuel based on load instead of dumping a fixed amount
at a particular boost pressure.  It's much easier and cheaper than an AIC
though and it's not like I'd be driving on it all the time so I may end up
going that way.
 
I have had on order a couple weeks now a rising rate FPR which I hope will
do the trick.

thanks
--Dan