Auto ECU MPG???

[S13n310]

will using an Auto ECU on a 5spd s13 lower my mpg??? After finishing up the swap i notice my car is drinking gas way more then it used to. I am almost at half a tank after 2 days doing my normal driving when pre swap I would only be a little less then a quarter. I tend to maintain a low rpm while driving, i am not speeding or raising my rpm high so i doubt its my driving... any comments anyone?

[Fastazz240]

i noticed that the auto ECU runs a lot ritcher than the manual one for some reason not sure as to why but it was that way on my s14

[corn322]

It shouldn't. I get the same MPGs in my S13 with either ECU.

[S13n310]

wonder if this is one of those things that vary by car... really killed my day to watch my gas disappear... i might try switching the ecu i guess :/

[biggie]

Or you are driving it harder because it is now 5spd?

[S13n310]

Or you are driving it harder because it is now 5spd?

nah... because i see it eating gas im not stepping on it nor letting it reach high rpms...

[breadbox]

the fuel maps are slightly different and autos do run a little richer, but I wouldn't say it EATS gas. did you lower your idle to 800-900 from 1100? The auto has a higher idle in neutral without a load on it.

[240nessx]

when i use to cruise with my 240 as auto it would be around 2600-2700 at 70, and now its 3200. i dont see it making ur engine eat as much gasas u say it does, but now that u dont have a torque convertor to lock to drop rpms, ur car will be driving at higher rpms when cruising then when it did as automatic.

[samxini]

when i use to cruise with my 240 as auto it would be around 2600-2700 at 70, and now its 3200. i dont see it making ur engine eat as much gasas u say it does, but now that u dont have a torque convertor to lock to drop rpms, ur car will be driving at higher rpms when cruising then when it did as automatic.

^ That's what I was thinking. I noticed a big difference in rpms at different speeds as well.
Oh well, gotta pay to play I guess.

[costa_rican13]

why not get a 5speed ecu? thats what i did. but i may switch to my auto ecu to remove my speed governor.

but i also thought that the autos have a leaner fuel map??

[94_240sx]

I got rough idle when I used manual ECU, so I kept auto ECU when I did the swap. Gas mileage was significantly improved after the swap.

[breadbox]

well in the case of SOHC's you can use any ECU made for a KA24e on a 5spd. I have a few 200sx ecus that had ka24e but also had consult wired stock.

[costa_rican13]

I got rough idle when I used manual ECU, so I kept auto ECU when I did the swap. Gas mileage was significantly improved after the swap.

really? looks like i'll be switching back then. hopefully i see the same.

[darens13]

i get around 25-27 with my 5 speed with auto ecu. no complaints about fuel economy from me.

[TheRealNap0le0n]

i knocked out 28mpg with my 5spd w/ auto ecu

[costa_rican13]

omg... yep switching first thing in the morning!

[costa_rican13]

so i swapped my auto ecu back in. and i went from a 700-800 rpm idle to 14-1500 rpm idle. wtf?

[TheRealNap0le0n]

just re-adjust the idle

[TimTurboZ]

I got rough idle when I used manual ECU, so I kept auto ECU when I did the swap. Gas mileage was significantly improved after the swap.

really? looks like i'll be switching back then. hopefully i see the same.

He meant gas mileage went up when he did his 5spd swap I believe. As in- he did a 5spd swap w/ a 5spd ECU and had a poor idle switched the ECU back to his auto ECU and it fixed his idle, after driving with the 5spd he noticed a mpg increase.

He was stating that going from auto to 5spd regardless of ECU he saw a MPG improvement oppose to you seeing worse results.

Your Fuel return line leaking lol, I'd make sure you didn't do something that could be making you lose this fuel while u did your swap.

[costa_rican13]

just re-adjust the idle

i did adjust it. and i screwed the iacv srew all the way in and it didnt even change but if i unscrew it then the idle raises 1500+ rpms.

[costa_rican13]

He meant gas mileage went up when he did his 5spd swap I believe. As in- he did a 5spd swap w/ a 5spd ECU and had a poor idle switched the ECU back to his auto ECU and it fixed his idle, after driving with the 5spd he noticed a mpg increase.

He was stating that going from auto to 5spd regardless of ECU he saw a MPG improvement oppose to you seeing worse results.

Your Fuel return line leaking lol, I'd make sure you didn't do something that could be making you lose this fuel while u did your swap.

ofcourse. lol

[S13n310]

havent had a chance to jump back on the forum but after driving it for a while it looks like its back to normal... first half of my tank was eaten in the first couple of days but fell on e today (filled up last sat) and did some heavy driving. So looks like its normal... i dont know if things had to settle or what but definitely saw my mpg go up in the last few days. thanks for the info, the auto ecu seems to be working fine in the car, i do notice the higher rpms, im im a little above 3000 at 70.