Can megasquirt be used to achieve better fuel economy???

Compaq888 · Post by **Compaq888** » Sat Dec 10, 2005 5:39 am

I have a auto, even my auto has fuel cut off?

20 degrees at idle. The car is NA, no turbo or supercharger. When I used to have nitrous I retarted the timing.

Enthalpy · Post by **Enthalpy** » Sat Dec 10, 2005 8:58 am

Yes, even an auto has fuel cutoff because the megasquirt has fuel cutoff. The OEMs put fuel cutoff in automatic cars as well.

I'm getting the feeling you don't have a megasquirt running the car. If your "base" timing is too advanced, you aren't doing yourself any favors mileage-wise or engine longevity-wise.

If you are using an SAFC on your factory-controlled engine, you aren't doing yourself any favors either. The SAFC is too basic of a controller to give you good mileage.

Compaq888 · Post by **Compaq888** » Sat Dec 10, 2005 4:26 pm

I am not running a megasquirt or a safc2. I was in the general section asking questions and it got moved here. I'm not going to pay crazy money for something and not have it work in my car. It's like shoot, then shoot some more and then ask the dead guy some questions.

20 degrees is stock for this car. The car is fully stock from the factory. All mods were taken off.

Enthalpy · Post by **Enthalpy** » Sat Dec 10, 2005 8:30 pm

Ah, now I see where you are coming from. I'm assuming you have done all the common sense stuff to improve your mileage (tire pressure, alignment, fresh oil, good ignition, clean injectors, working EGR, etc.).

In that case, take a look at your O2 sensor. If there are 5 wires coming out of it, then you have a lean burn engine and you probably won't see improved mileage by going to an EMS. If you see 4, then you very well might.

The way you get better mileage out of an EMS-equiped car is better injector spray/location, the freedom to tune for mileage without much concern for emissions, and the fact that you can run lean burn maps in closed-loop. Just how much additional mileage you get out of it depends on the engine.

Compaq888 · Post by **Compaq888** » Mon Dec 12, 2005 10:28 am

Enthalpy wrote:Ah, now I see where you are coming from. I'm assuming you have done all the common sense stuff to improve your mileage (tire pressure, alignment, fresh oil, good ignition, clean injectors, working EGR, etc.).

In that case, take a look at your O2 sensor. If there are 5 wires coming out of it, then you have a lean burn engine and you probably won't see improved mileage by going to an EMS. If you see 4, then you very well might.

The way you get better mileage out of an EMS-equiped car is better injector spray/location, the freedom to tune for mileage without much concern for emissions, and the fact that you can run lean burn maps in closed-loop. Just how much additional mileage you get out of it depends on the engine.

Yes I have done almost everything to get the mileage up. Changed the spark plugs to copper ones, changed spark plug wires to better ones, changed to a new distributor cap and rotor, did a tranny and radiator flush, and there is some other things.

You know I was thinking of getting lighter rims so my street mileage would go up. My oem wheels are 20.6lbs. You think shaving 6-7 pounds a rim will improve street mileage because the engine has less to push?

Enthalpy · Post by **Enthalpy** » Mon Dec 12, 2005 1:18 pm

On paper, of course. In practice, I'm not sure how much it would save. That's probably dependant on how much stop and go driving you do.

If you are in the Denver area, I can help you tune your setup for better economy if you are interested.

Compaq888 · Post by **Compaq888** » Mon Dec 12, 2005 5:03 pm

I will have to see. I still have a few ideas up my sleeve. My goal is just to get the street 25mpg. If I don't reach that goal I will have to look at what megasquirt I'll buy.

Enthalpy · Post by **Enthalpy** » Mon Dec 12, 2005 6:58 pm

I know you have an automatic transmission, so that might complicate this, but if you can get to the point where you are controlling ignition and fueling, you can probably get better mileage.

TurboCamaro · Post by **TurboCamaro** » Tue Feb 28, 2006 10:55 am

You mentioned tuning a stock 1999 Altima? My wife has a 2002 3.5L Altima. I know they changed a ton on things with the newer ones, let alone it's a different engine, but are there DIY tuning options for these cars?