CVT swap? (Into 2005 Civic, replacing 4-spd auto)

[Ecky]

See here: https://ecomodder.com/forum/showthre...ing-27416.html

[cRiPpLe_rOoStEr]

Originally Posted by EcoCivic

How exactly is the EPA's testing procedure biased? Do they assume that the driver of the manual trans doesn't know when to shift or something?

IIRC it has to do with a standardized shifting procedure for test purposes, which ignores some differences between so many engine configurations. Then it led to close-ratio manual transmissions becoming more widespread, even though their gear-spread may be more suitable for a "sporty" driving mode than to improve efficiency.

[EcoCivic]

Finally swapped the 5 speed in and wow what a difference! The car now feels much quicker and way more fun to drive and my MPG improved from about 31 at best with the auto to 38 consistently over 2 tanks of doing the same kind of driving with no special techniques. How I picked up ~7 MPG just from changing a transmission I have no idea but I'll take it! I think there's more in it too. Once I learn what shift points and RPM it likes, get a proper alignment, and have the proper 5 speed ECU flashed and installed so I can coast properly I think I will easily be getting 40+ MPG with this transmission.

[cRiPpLe_rOoStEr]

Originally Posted by EcoCivic

have the proper 5 speed ECU flashed and installed

Not sure to which extent it may increase fuel savings even further, but a manual compared to those earlier 4-speed automatics is light-years away when it comes to fuel-efficiency.

[EcoCivic]

Originally Posted by cRiPpLe_rOoStEr

Not sure to which extent it may increase fuel savings even further, but a manual compared to those earlier 4-speed automatics is light-years away when it comes to fuel-efficiency.

I think the auto ECU doesn't understand coasting because when I push the clutch in or shift to neutral while moving the engine doesn't idle normally, the RPM jumps between about 1500 and 2500 over and over again about once per second. But as soon as I come to a complete stop, the idle drops down to normal. If I unplug the speed sensor so the ECU doesn't know that I'm moving it idles correctly while coasting also. This must have something to do with the ECU because there is mechanically no difference between idling while sitting still and idling in neutral or with the clutch in while moving.

[cRiPpLe_rOoStEr]

Originally Posted by EcoCivic

This must have something to do with the ECU because there is mechanically no difference between idling while sitting still and idling in neutral or with the clutch in while moving.

Interesting. AFAIK there were other models of a similar vintage with a similar 4-speed automatic which had a more coasting-friendly tune, I just don't know if any Honda had it outside the United States and Canada.

[EcoCivic]

Originally Posted by cRiPpLe_rOoStEr

Interesting. AFAIK there were other models of a similar vintage with a similar 4-speed automatic which had a more coasting-friendly tune, I just don't know if any Honda had it outside the United States and Canada.

My ECU is from a JDM Honda Stream, not sure if that matters. It coasted perfectly fine with the automatic transmission. But now that I have a 5 speed, it's not happy when coasting. I'm thinking the ECU either doesn't know that it's supposed to be controlling the idle since it doesn't know that it's in neutral or the ECU can't bring the idle down far enough now that it doesn't have the load of the transmission's pump on it anymore. If I turn the AC on while coasting the extra load stops the engine from surging, but it still idles quite high at around 1800-2K RPM until I come to a stop. As soon as I completely stop, the idle returns to normal.

[cRiPpLe_rOoStEr]

Originally Posted by EcoCivic

My ECU is from a JDM Honda Stream

I have seen only one Honda Stream, but it was Euro-spec AFAIK.

I'm thinking the ECU either doesn't know that it's supposed to be controlling the idle since it doesn't know that it's in neutral or the ECU can't bring the idle down far enough now that it doesn't have the load of the transmission's pump on it anymore.

Probably it's because the ECU doesn't get any signal input from the transmission in order to identify which gear is engaged. And since many automatics already start moving as soon as the brake pedal is released when in gear, the ECU increases the RPM because the other electronics don't deliver a speedometer signal.

[EcoCivic]

Originally Posted by cRiPpLe_rOoStEr

Probably it's because the ECU doesn't get any signal input from the transmission in order to identify which gear is engaged. And since many automatics already start moving as soon as the brake pedal is released when in gear, the ECU increases the RPM because the other electronics don't deliver a speedometer signal.

That's pretty much what I'm thinking, hopefully getting the correct ECU installed fixes the problem. The problem is all the locksmiths around me want $250-$300 to flash the new ECU to the key and immobilizer. The dealer will do it for $135 plus tax but I'm hesitant to take it to them because my last experience trying to get an ECU flashed there a few years ago was very negative.

[cRiPpLe_rOoStEr]

Originally Posted by EcoCivic

I'm hesitant to take it to them because my last experience trying to get an ECU flashed there a few years ago was very negative.

Even though nowadays a dealership makes a large profit from service, trying to push customers into something newer for which they may be able to charge a higher fare due to the increased complexity seems advantageous. No wonder they often perform services with fewer care once the vehicle is older, plus it leads to fewer need to keep spare parts for them on inventory.