Can't Get Good Fuel Economy - 2008 Civic Manual

[whatjigg]

Yes, KJSatz, i too am very interested in knowing what kind of MAP values to expect that indicate the change to i-VTEC.

Overall the R18 seems to a very sophisticated little beast. But from reading the link you posted along with another tech brief from the same place that overviews all of the engine's features, it seems to me that the key to getting into and maintaining position in i-VTEC operating mode is to be very very light on the gas whereby rpm's matter quite a bit less. It also states that other factors are taken into account by the ECU --> this brings me back to my first questions about RESETTING the ECU. Is the ecu learning some of my driving behaviour and thus forcing performance over fuel economy more often than not? From what I understood prior to this, the grand majority of low end cars do not have ecu's of this kind and that 'learning and adapting to driving behaviour' type feature only comes with a porsche or likewise.

The fact that rpm's are almost irrelevant as long as one is between 1000-3500rpm's with an R18 engine makes me wonder about my past driving techniques. Now I am definitly starting to see where a scangauge would've helped quite a bit in figuring out this quite a bit earlier (although I wouldn't have a clue as to why). Assuming the ecu is smarter than what's good for it, do you think resetting the ecu would provide an opportunity to help retrain the ecu to the tunes of fuel economic driving? any other benefits/problems with the reset?

[whatjigg]

I was just reading over the earlier posts, now I had said i thought i was only about two mpg under you kjsatz. But in fact I'm more like 10-11mpg less than what you achieve on the highway assuming you were talking US gallons. I get about 34-35 mpg (US gallons) and about 41 mpg (Imperial Gallons). While you get 5.3L/100km, i get 6.9L/100km on highway.

[dichotomous]

Originally Posted by whatjigg

Oh and anyone have any ideas/opinions with respect to resetting the ECU?

hondata kpro, will allow you to adjust your ecu so that while being all hypermiler and gentle, it barely even sips fuel, then when you stab the pedal its instantly a strong and powerfull gas guzzler, eco when you need it, fast when you need it, neither when you dont. thats why I like honda's vtec and vtc systems, you can have your cake and drive it too

[fanamingo]

Resetting the ECU does reset some learned engine parameters. According to the shop manual, this includes crank pattern learn, idle learn, readiness codes, freeze data, on-board snapshot, and DTCs. If you do this, I recommend doing it when the engine is already fully warmed (you'll waste less gas doing the next step). The shop manual then recommends doing the idle learn and crank learn procedures. I tried the crank learn procedure, but it didn't work for me and wasted a fair bit of gas (involves repeatedly accelerating to 5,000 rpm). It should learn what it needs through typical driving over the following days. Be warned that resetting the ECU requires you to reenter the radio code afterwards. Also, resetting trouble codes with a scan tool clears the ECU as well.

Idle learn:

1. Turn off all electrical items.
2. Reset ECU (called ECM/PCM).
3. Turn ignition switch ON (II) and wait 2 sec.
4. Start the engine. In Neutral or Park, hold rpm at 3,000 until radiator fan comes on or coolant is at 194F (90C).
5. Idle for 5 minutes with throttle fully closed.

[dichotomous]

as far as resetting the ECU, usually pulling the battery for a few mintues will do that. there is a process on the Kseries engines to have it relearn idle, which it learns on constantly, and yes your car learns your driving a little and adapts. this will clear all that.

as far as the RPMS go, I find that anything under 3,000 doesnt really matter on mine, and most people find similar, mine is a bit larger and K architecture, but my old D16z6 was the same way. my dad constantly got 40mpg from that only with ecodriving (this was back a decade or more ago too) like coasting everywhere, using engine power as little as possible, accelerating smoothly but not lugging, he'd even key off when he was reasonably close to a parking space.

but look into hondata Kpro, for the best of both worlds out of your honda, it WILL take away the learning ability, but it will open the door to almost infinate engine adjustability. cam angle, cam selection (big or little lobe, vtec but not just one changeover I think), ignition timing, cam timing, fuel injection. (it also will control turbo boost, nitrous oxide flow, and all the specific settings that will make the engine run best at each point with those.)
the crappy part is that it takes a lot of tweaking and testing (it will run a test while driving and record all the sensors to tell what the engine is doing). its the ultimate tweakers tweaker. for my car it runs about $1000 and you need to use a laptop with it in the car to make changes or record testing

[KJSatz]

Unfortunately I do not have a scan tool or anything. When I say you can see a jump in the MAP, I am giving second hand information. I think I read about it on cleanmpg.com in a really long thread about the 8th Civic. So I don't know what sort of numbers you'd look for.

[whatjigg]

dichotomous - that sounds like a very neato tool, although i'm not sure i'm ready to drop $1000 on it, you think the dealership could do some of these tweaks?

I think what I'll try after purchasing a scangauge2 on monday, is get a baseline established then try resetting the ecu along with the crank learn & idle learn (i do have the radio code saved so np there).
Fanamingo --> how do you 'know' the crank learn didn't work? and do honda dealerships sell the shop manual or do i have to go elsewhere to get ahold of it?

[dichotomous]

Originally Posted by whatjigg

dichotomous - that sounds like a very neato tool, although i'm not sure i'm ready to drop $1000 on it, you think the dealership could do some of these tweaks?

I think what I'll try after purchasing a scangauge2 on monday, is get a baseline established then try resetting the ecu along with the crank learn & idle learn (i do have the radio code saved so np there).
Fanamingo --> how do you 'know' the crank learn didn't work? and do honda dealerships sell the shop manual or do i have to go elsewhere to get ahold of it?

naw, I dont think the dealership can change those things. the cost is also why I havent got one

[Christ]

Originally Posted by KJSatz

Lean burn is different. Civic HX and VX of old, and the current hybrid's ICE, have lean burn. That actually changes the ratio of fuel to air in the mixture. What our R18 does is partially retract some of the charge so that less of the mixture is used. I think it's pretty clear in the second link in my first reply here. Also, calling it VTEC would be incorrect. If you are in a lower load situation from 1000 to 3500RPM, you will probably be in VTEC, but you won't be in this weird thing unless you're in especially low load. At least that is the way I understand it; if they are activated only with each other, I am mistaken.

VTEC - change in the cam's profile. (Variable Timing Electronic Control)

You're in Vtec anytime the Cam changes profiles, i.e. when the engine is using a different airflow profile while running.

The lean burn characteristic, (as far as I know) comes from running in Vtec mode. The point of lean burn is the same as CVCC was, just doing it in a more efficient way (supposedly). It's supposed to inject a very rich mixture into the cylinder before adding air/fuel at a very very lean mixture... the rich mixture ignites, and will still burn the rest of the mixture with max efficiency.

When you change the profiles of the cam in the R18 iVtec engine, all you're doing is changing the intake cam's profile to allow the intake valve to remain open longer so the cylinder will lose some of it's air. This is an example of a variable atkinson cycle.

[fanamingo]

Originally Posted by whatjigg

Fanamingo --> how do you 'know' the crank learn didn't work? and do honda dealerships sell the shop manual or do i have to go elsewhere to get ahold of it?

I was wrong about the crank learn procedure not working. The CEL blinks a certain way after you start the car if the emissions readiness codes aren't set yet. I was mixing that up with the crank learn procedure.

I got the service manual at the below link. I couldn't find it with a quick search, but it's there somewhere. You can also purchase it through a dealer.
http://www.helminc.com/

Edit: direct link
http://www.helminc.com/helm/product2...e=&Sku=61SNA05
It says it's for the Si, but it also covers the regular Civic.