Map type- 250 and 115 kPa. How does it affect tuning?

[malloy1]

Just wondering how map type affects tuning?

I have 250kPa map type selected and MS tuned, but I get lousy gas mileage. I’m pretty sure I have a 250 kPa map, but just wondering if I’m wrong.

I got my MS finished up a couple of weeks ago, and been checking out the gas mileage, and after a couple of tank fill-ups, the gas mileage came out about 21 miles per gallon (and that's highway mileage (65-75mph)!-I drive 60 miles a day on a fairly flat, good flowing highway). I was hoping for more like 25-30 miles/gal. The car has plenty of power, but the gas mileage is awful.

The engine is a stock Volvo engine from a '79 Volvo 240 that I transplanted into a '65 Volvo 122.

The setup is:
-'65 Volvo 122 with a Volvo B21F engine/M41 transmission (stocked, not modified normally aspirated engine)
-LC-1 WBO2
-MS V2.2 running MSnS-extra (24s13) fuel only - tuning with MT2.25b514 and VEXME
-original '79 Bosch iginition setup from a 240
-Bosch 21lbs EFI injectors
-Volvo 850 Bosch TPS
-EGO crossover is set to 2.5v
-AFR is set to 14.7
-K&N air filter

I've checked the error on the odometer at around 3% fast, and the speedometer is around 5% slow. Which I find acceptable for a 40+ year old car.

I figured that a Volvo 122 total weight (a Volvo 122 total car weight is 2400 lbs vs a Volvo 240 total car weight 3000 lbs), running EFI, and a WBO2 sensor would produce better fuel economy than the original K-jet setup (The original Volvo 240 fuel setup gets about 25-28 mpg?)

Doesn't seem right that the stock setup gets about 30% better fuel economy than a MS setup? Especially since this is not a performance setup.

Could it be that I have the wrong setting selected for map type? The MS kit I purchased from Digikey in April 2004.

I just changed the map type setting from 250 to 115 kPa, and the car went from really rich at idle to really lean at idle (and died).


Paul

[Bernard Fife]

Paul,

You have a 250 kPa MAP. All MegaSquirts (from B&G, some suppliers sell higher rated MAP sensors with their kits, I believe) have been this way for quite a while.

Have you tuned the VE table to maximize the fuel economy? There's more on that here: http://www.megasquirt.info/v22manual/mtune.htm#economy

Lance.