Thread: Neutral Coast Not So Great for Fuel Economy

i imagine they do tune like that, in your situation i imagine you are losing so much power from not being able to really full on tune the car and being limited with the jwt ecu, you would benifit so much with a real time, or stand alone...so much more power would be unlocked

From what I've seen, fuel saving driving techniques make a significant difference.
Yesterday: ~55 mile trip (about 15 city/40 hwy), avg 49mph, 37.6mpg.
Return, different route, 65 miles, mostly hwy, avg 57mph, avg 38.5mpg.
This morning: 14.5 miles, only about 4 miles @ 55, rest 25-45mph, mostly city, avg 33mph, 38.6mpg.

At least that's what the ECUTalk scanner said.
On the longer trip yesterday, google maps said it should be 65.0 miles, ECUTalk scanner said 65.1, so it's pretty accurate as far as the distance goes.

This is for a B13, most bolt-ons, S4 cams, JWT ECU programmed for pop charger (no cam program), about 154 lb. weight reduction. With 5th gear pop out, have to hold it in all the time. Still pops out holding it in with too much load - doesn't take much.

JP you've always been the only other pro MPG person that I know

BTW what are the numbers that you get for when you fuel up at the gas pump? Are they similar to what ECUtalk says?

hmm...didn't know neutral coasting was bad. i'll have to stop that. i thought that keeping the car in gear with the engine revving would be using gas. that's a strange concept, but if it saves on gas i'm for it. neutral coast no more. thanks for this tip.

Many people enjoy (literally have as much fun as we do) driving for economy as much as you and I enjoy driving for speed.

Haha good point! I personally enjoy driving because I like to drive fast. But I wouldn't mind a good economy while driving fast haha

i coast down hills and my calcualtions on mpg have been ~2mpg better since i have been doing so.

this may be true in an auto transmission car but how can you argue that 3-4k rpms in 5 gear and about 65mph is using less gas the 800 rpms in neutral? (or 0 rpms as it is for me on the big hills)?

^^ that's what i was thinking too. but it sounds like if you coast in gear the car shuts the injectors completely off. which would be better than idle, lol.

i don't understand how the rpms are going with no fuel moving though. can someone explain this? is it something to the effect that the tranny is spinning the motor.

Easily, and this trick probably doesn't work so well on Auto's because of automatic shifting.

How it is easily? When you are in gear and going down hear the wheels are spinning the transmission, which spins the flywheel, then the crank. Thus the engine is still technically running, but no fuel is needed to keep it running.

While you are idling you have nothing to keep the crank spinning, thus the engine needs to keep on running by throwing the fuel in etc.

Not sure - haven't run a full tank yet on the daily driver since I got the ECUTalk reader.
It loses trip information when you turn the key off, starts from 0 every restart.
They're working on new firmware that will possibly allow a microSD card to log data though,
then you could add the log data up for that tank.

I still have fun driving it hard now and then, not always driving for fuel economy.
Badly worn 5th gear forces me to really baby it while still holding the shifter in hard.
Gotta get the trans fixed or replaced, getting sick of it.
Peak recall said 7687 RPM this morning -
Had to go a different route with crummy traffic, stop lights, construction, still 35+mpg.

If I put harder compound touring tires on, i would get even better mpg.
Summer only 320 treadwear AA traction tires have more rolling
resistance, but not so bad with higher tire pressure.