1997 Civic CX to HX engine/VX trans swap! 63 MPG @ 62 MPH

[brucepick]

turbovr41991,

Now that lean burn is working a bit better for you, try for some lower speed LB this way:

Once you have LB at 65-70 mph or whatever speed works for you, lift foot very slightly so speed starts to drop very gradually. See at what speed LB is lost. If all is well one day you will have LB down to about 1800-1900 rpm. That is very useful indeed.

REMEMBER the ScanGauge updates only once per two seconds. So your visible gauges there are always delayed behind reality. Don't lift foot too fast or ScanGauge will be so far off it will really be lying to you.

[brucepick]

Oops I blew away a recent post with answers to your questions. I'll try rewrite it later tonight or on the weekend.

(sorry!!)

[turbovr41991]

Originally Posted by brucepick

Calibrating the Guino is reasonable but requires patience and a degree of neediness.

On the highway I USA a sort of lean burn P & G. Accelerate at max throttle that won't go out of LB, till I reach my max decided speed. Then coast in neutral down to my min decided speed. Then back in gear, throttle to about 65 LOD, get LB again and accelerate, rinse and repeat. Modify as needed to accommodate terrain and other vehicles.

Good that your tall tranny allows some coasting in gear. Experience will tell if it's better than coasting at idle. Coast in gear may prevent lean burn after that; you will see. My car will meed a shutdown and 2 miles drive to allow LB again, if I coast in gear.

lol, looks like I found it in my email. Might save you a little time.

[brucepick]

THANKS!! for saving what I wrote, and my time!!

I finally got my phone to cooperate. So here it is with typos corrected.

Calibrating the Guino is reasonable but requires patience and a degree of nerdiness.

On the highway I use a sort of lean burn P & G. Accelerate at max throttle that won't go out of LB, until I reach my max decided speed. Then coast in neutral down to my min decided speed. Then back in gear, throttle to about 65 LOD, get LB again and accelerate, rinse and repeat. Modify as needed to accommodate terrain and other vehicles.

Good that your tall tranny allows some coasting in gear. Experience will tell if it's better than coasting at idle. Coast in gear may prevent lean burn after that; you will see. My car will need a shutdown and 2 miles drive to allow LB again, if I coast in gear.

[turbovr41991]

Still waiting on an MPGuino. I have gone through one tank with MMO with a little success. On my second tank now. Also plan on making it more aero friendly to help at the higher speeds and lean burn.

I installed a new O2 the other day which got rid of the occational CE light.

Just installed oem tune up parts. Honda plugs, wires, cap and rotor. none of which looked bad, but all was off brand. Now its all OEM. I also added a stock housing K&N filter. not sue if that will help or not, but firgured it is worth a try. Next on the list is a better cleaning of the EGR and passages. There has to be a trick to these HX's going into lean burn at lower RPMs!

[Jakins]

Hey so how has your vx tranny been treating you with the hx motor? I might be picking one up real soon! I'm just worried it won't have enough power to get up some of the hills in 5th gear at lower speeds haha

Correction..... The tranny I was going to get got stollen this morning serves me right for getting excited

[turbovr41991]

I would like to apologize to anyone reading this and hoping for a quick answer. This is not as cut and dry “my car got 30 mpg and now get 50 mpg” as seen from some of these VX engine and transmission swaps into different vehicles, so please, bear with me. From what I have seen, the potential is there for me to get above 60+ mpg, but just need to master the technique to accomplish it.
As for the HX engine mated with the VX trans, honestly, I am still figuring it out. With the HX engine I have a lot more options and I am still trying to work them all into their ideal spots in my route. My HX engine seems to limit lean burn entry to about 2500 rpm. I have been told that is not normal and I am trying to figure out what is limiting me. After two tanks of “testing “ lean burn at 2500 RPM in 5th gear (or about 75 mph) I can say it stays in lean burn quite well at high speeds. I would like to think my drag would be better than a stock HX by not having power steering, and having a few aero mods to lower the resistance. In any case, it did not struggle at all as long as my RPMs were high enough (2400 to 3000).
Going this fast is not conducive to good gas mileage, so I have all but given up on 5th gear lean burn. With the exception of long trips with the family and speed limits of 70+ mph, I think I will leave that alone. I am sick of getting poor gas mileage in my “Testing”. If my situation changes and lean burn starts working at 1800 rpm, I will then start testing 5th gear lean burn again. Today I tested its “true” ability with a fresh tank of gas, MPGuino, and Scangauge2. My trip in this morning averaged 58 mpg without ANY ECO. This is a personal best for me not using any ECO. There are a few spots where I would like to use EOC, but not I am afraid I would not be able to get back into lean burn fast enough to climb the hills directly after. I guess it just takes some testing to see if it is better to DFCO down the hill and lean burn back up or if it is better to ECO down the hill and then normal burn 5th gear up the hill. My guess is it will vary and depend on the hill.
In the end, I feel the addition of the HX engine is a huge plus. It is like having a tool set and adding a set of gear wrenches to it. The gear wrench might not make the most sense all the time, but it sure is beneficial to have in certain situations. It is always good to have more options!
Sorry to hear your potential VX transmission was stolen. I am sure another will pop up.

Originally Posted by Jakins

Hey so how has your vx tranny been treating you with the hx motor? I might be picking one up real soon! I'm just worried it won't have enough power to get up some of the hills in 5th gear at lower speeds haha

Correction..... The tranny I was going to get got stollen this morning serves me right for getting excited

[Jakins]

Man I wish I could help with your situation. Are you positive you don't have a vacuum leak? Maybe you need to think of some of the other things involved. I've been messing with mine. I have my pcv venting into the atmosphere right now rather than the intake because I feel like If I have oil leaks than that could translate into vacuum. So i capped that off. Does the vtec not work off of oil pressure? I notice a difference when my oil is low. Or am I thinking of other variable valve timing cars. Also I've heard vtec-e likes slightly advanced timing. Im sure you have done that already but I'm just trying to throw ideas out there. Maybe it is still adjusting to the new o2 sensor. Who knows. I know the d16y7 and y5 have different intake manifolds maybe its possible you routed a line the wrong way? Such as the evap

[California98Civic]

Originally Posted by turbovr41991

My HX engine seems to limit lean burn entry to about 2500 rpm. I have been told that is not normal and I am trying to figure out what is limiting me. After two tanks of “testing “ lean burn at 2500 RPM in 5th gear (or about 75 mph) I can say it stays in lean burn quite well at high speeds.

The stock HX with a final drive of 3.750 (I think) and 14" wheels would have hit 2500 RPMs at a much lower speed than 75 mph. Your VX 3.250 final drive combined with wheels that are 14" instead of VX stock 13" may be the "problem" requiring a significantly higher speed to allow LB ... perhaps there is a way to fool the ECU? What sensors does it use to determine LB?

[turbovr41991]

Originally Posted by Jakins

Man I wish I could help with your situation. Are you positive you don't have a vacuum leak? Maybe you need to think of some of the other things involved. I've been messing with mine. I have my pcv venting into the atmosphere right now rather than the intake because I feel like If I have oil leaks than that could translate into vacuum. So i capped that off. Does the vtec not work off of oil pressure? I notice a difference when my oil is low. Or am I thinking of other variable valve timing cars. Also I've heard vtec-e likes slightly advanced timing. Im sure you have done that already but I'm just trying to throw ideas out there. Maybe it is still adjusting to the new o2 sensor. Who knows. I know the d16y7 and y5 have different intake manifolds maybe its possible you routed a line the wrong way? Such as the evap

Not sure on the vacuum leak. I don’t think there was much of an opportunity to miss anything. These engines are pretty simple and most things just fall into place.

Originally Posted by California98Civic

The stock HX with a final drive of 3.750 (I think) and 14" wheels would have hit 2500 RPMs at a much lower speed than 75 mph. Your VX 3.250 final drive combined with wheels that are 14" instead of VX stock 13" may be the "problem" requiring a significantly higher speed to allow LB ... perhaps there is a way to fool the ECU? What sensors does it use to determine LB?

I am running the stock 14 inch HX wheels with new Michelin Defender tires. Tires and speed sensor I don’t think are the issue. Even in lower speeds and gears I still almost always need the 2400 to 2500 requirement for lean burn. Bruce had the same issue in his stock HX. He said it went away or improved from using MMO. I am on my third tank with MMO now and hoping to have some improvement.

Thus far the sweet spot for lean burn seems to be in 4th gear at 2300 – 2500 going 57 – 65 mph. On flat it seems to be averaging 21% throttle, 50-60 LOD and netting 60-63 mpg.