The statement has been made that maxing out the MAF isn't really a problem because the PE vs RPM table can be adjusted to compensate. I don't fully understand how this is done.

I could see modifying the table to gradually richen the commanded AFR as RPM increases above the point at which saturation occurs. Then you could back into an acceptable fuel curve through trial and error. Is this the method people are referring to or is there another way?

 

Anyone?

 

Simply put ....

You can add more fuel at WOT by increasing the values in that table. This table is independent of the MAF reading. Thus, you can add lots of fuel without worrying about MAF readings. The problem is that this is only at WOT. This does not solve the part throttle fuel curve problem. That problem still exists because that table is only used during PE (WOT).

Tim

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TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

If someone's maxing out the MAF sensor and they're not in PE, they have a whole 'nother problem. Generally, there won't be a part throttle fuel problem with a MAF since it's "reading" airflow, unless the engine has a seriously big cam with a small LSA.

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Greg Westphal
'87 IROC 305TPI/A4

 

Greg ...
You have misinterpreted my use of Part Throttle. Part Throttle = anytime you are not in PE. This includes driving up a hill where LV8 will be very high. The MAF could max out and you would be screwed. We are saying the same thing.

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

Thanks for the replies. Since the highest hill around here is the freeway overpass high MAF values really only occur in PE. That and I don't have enough engine to max out a MAF under any condition (yet...)

 

Yes but if you have a very high LV8 that does not mean you have hi airflow. In fact LV8 is usually high going up a hill while airflow is low. At least that is what I have seen. With my MAF 396 vette, my airflow maxes out at 3950 RPM at WOT but at non PE modes I have had it up to 5300 with airflows well below that (30% throttle). In fact I can't seem to max it out with PE enabled at 40% throttle.