Stock MAF systems

[Robert Gallant]

Howdy;

I've been playing with the stock fuel injection mounted to a
supercharged Rx7 (positive displacement type).

I measured the voltage from the MAF and noticed that it was wide open
before the car was at max RPM and WOT.  The O2 sensor voltage looked
fine up to just after the MAF was wide open, then it would start to lean
out.

I opened up the MAF and tightened the spring (its adjustable).  To make
up the difference in fuel delivered, I installed larger injectors.

Now the MAF voltage is almost wide open at WOT, 8000 RPM, 30 deg F.  A/F
ratio looks good all the way to redline without dropping at high RPM.

Now for the big BUT:  The system has an intermittent drop in O2
voltage.  One instant O2 is nice and rich, a few miles later its running
a bit lean (at WOT and approx the same RPM).  O2 on the car is usually
rock steady, even at WOT (well, at least when it was stock).

I've started to check out the sensors for problems (IAT, water temp, O2
sensor,....) and haven't found the problem yet

Do stock systems use the MAF all the way to redline and WOT, or do they
typically go wide open before that point and use a lookup table for fuel
delivery.

Thanks
-- 
Rob
MailTo:gallant at oasys.dt.navy.mil