MAP direct correlation to FE?

[sword_guy8]

Originally Posted by Old Mechanic

The chart is the result of load and MAP. Load and MAP create the chart. Can you tell which engine is in a car by looking at the exhaust?

Isn't MAP an indication of load? As in, on and the same? And yes, I can tell an engine by its exhaust, but what does that have to do with anything?

Also, can you please explain how load and MAP are used to create the chart? I'd love to learn how dyno testing is done. I always thought they just had a tool to measure and vary torque while they measured fuel consumption at different RPM.

[P-hack]

Generally we say that map and load are two ways of looking at the same thing (for a given rpm).

maybe this will help you with the relationship between map and load:
ALDL revealed and TPS conversions
If LV8 is the load variable in counts, then:
Vacuum = 80 - (5/16)*LV8 Kpa
1 ATM MAP = 20 + (5/16)*LV8 Kpa
2 ATM MAP = 30 + (5/8)*LV8 Kpa
TPS(in % open) = (25/64)*LV8
Load = (5/16)*LV8

[gone-ot]

That's VALID only *if* GM is still using exactly the same conversions under current OBDII as they used for those mid-1980's Assembly Line Data Link (ASDL) codes.

[sword_guy8]

My car is from 1989. With a 1993 engine in it (still OBD 1).

[P-hack]

my point is that there is a direct correlation between MAP and engine load, and so that is the basis for intepreting/creating a bsfc map without a dyno.

[user removed]

Originally Posted by sword_guy8

Isn't MAP an indication of load? As in, on and the same? And yes, I can tell an engine by its exhaust, but what does that have to do with anything?

Also, can you please explain how load and MAP are used to create the chart? I'd love to learn how dyno testing is done. I always thought they just had a tool to measure and vary torque while they measured fuel consumption at different RPM.

And you would be the only person on the planet so gifted as to be able to tell the engine by the exhaust, yet unable to understand MAP and load.

[sword_guy8]

First of all, I was clearly joking about the exhaust thing. Second, instead of telling me I don't understand, why don't you explain the correlation (thereby causing me to understand)? I mean, since you're the expert, wouldn't you want to teach the correct things to people who aren't? I'm pretty sure I explained my understanding, and that P-hack confirmed what I was saying.

[P-hack]

here is a thread, map is only good for one temperature/rpm basically.

http://ecomodder.com/forum/showthrea...ion-19078.html

per the ultragauge manual load is current airflow/peak airflow (for a given rpm I presume). Mass airflow is a function of a few things, like temperature, not just pressure, as temperature affects density.

[Mustang Dave]

Originally Posted by Old Mechanic

Above 80% the ecu enrichens the mixture for more power and mpg suffers due to enrichment.

That doesn't seem to be the case with my '07 Mustang. Accelerating on the freeway on-ramp leaving work, I regularly hit 100% load on my UltraGauge without going into open-loop. Shifting @ 2500 RPM, I'm getting 6-8 MPG in 3rd, 8-10 MPG in 4th, and 13-15 MPG in 5th while accelerating to 65 MPH. YMMV.

[P-hack]

thing to remember is that you are talking to a computer, which can do whatever it wants with the data stream. Open loop might not be a reliable enrichment indicator. Heck unless you tap sensors/injectors directly and feed them into your own computer and calibrate (or really really understand the firmware in your ECU) then there is going to be a lot of guesswork and unknowns.