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

[brucepick]

Originally Posted by turbovr41991

... I also used the stock CX VSS. Speed reads slightly faster than the actual speed by 2-3 mph. However, the odometer miles are actually about .5 to 1 mile LOWER than what the gps says in distance traveled on a full tank... I guess the stock cluster is inaccurate to some extent on speed. I have fine tuned my MPGuino to be dead on with the GPS speed which is a much better method...

My HX has the stock VSS and tranny and I see the same error on the OEM speedo and odo. I used the same solution: my MPGuino is carefully calibrated to my GPS and those Guino numbers drive my fuel log and mpg numbers.

[Ecky]

Originally Posted by brucepick

My HX has the stock VSS and tranny and I see the same error on the OEM speedo and odo. I used the same solution: my MPGuino is carefully calibrated to my GPS and those Guino numbers drive my fuel log and mpg numbers.

Yeah, my MPGuino reads the correct speed as well, but the cluster isn't hard to fix. The spring getting weak makes it read incorrectly by a fixed amount, so moving the needle back corrects it perfectly.

[turbovr41991]

Originally Posted by Rusty94cx

the Eco shop as you probably have seen has the hx ecu now. I want to know what they are running and what software.

They are using an OBD2 to OBD1 jumper harness and a P28 or equivalent ecu. In talking with them, they said I could just get a jumper harness and use the VX ecu (as you suggested), but it would not be ideal and for the money, I might as well get a tuned ECU for optimal lean burn specific to the HX.

Originally Posted by Ecky

I've found that the springs on these older Honda clusters tend to get weaker over time which results in the speed reading high. To fix this on my cluster I simply popped the needle off and stuck it back on 3mph lower.

Thos would make a lot of sense. Honestly, I do not mind it reading higher than what I am going. I have a hard enough time convincing my wife we are going “fast enough.” This miscalculation actually aids me when I can point and say “look we are going 65 mpg” when we it actually is reading 63-64 mpg and my real speed is right at 60. lol

[Rusty94cx]

Why wouldn't it be ecconomal? You can get a harness for 100$ and I got my spare p07 for 50$. So under 200. As for a truely tuned setup requires hondata 300 setup completely tunable on thy fly from laptop, and that is 600$ plus a obd1 ecu and a jumper harness. Heres a link for a jumper harness.
Rywire : OBD2a to OBD1 ECU Conversion Harness - $75.00
I'm pretty sure that's the one you need.

[turbovr41991]

Originally Posted by Rusty94cx

Why wouldn't it be economical?

I think you might have taken this out of context. To clarify, I intended to say:

1) It would not be ideal. (meaning the VX ecu would not be as precise as it is designed for a different engine and apparently unable to be tuned. I do not want to give up drivability or have suboptimal fuel maps.)
2) For the money, I might as well get a tuned ECU for optimal lean burn specific to the HX.
From what I have been told, the price would be much cheaper than what you listed above, but we are still waiting for their final results, options, and pricing.

[Rusty94cx]

No i sp[oke to them also I'm not sure that you'll be able to use your scangauge? ie its an obd1 ecu . Just a thought. Yes you cannot chip a p07 ecu but the p28 can and the p05 p06 can they just need a little soldering done to them. no you would have a chipped ecu and thats what it would be it's tuned but not really to your car or driving habbits. It would be a generic setup, not that thats bad just what it would be pm and ill tell you what he quoted me for a vx ecu setup with 02 delete. I can do the same myself for well pm me if you want to know. The only reason i had suggested the vx ecu was to see if you could achive lean burn easier. I believe that there are no 2 mile first and so on limits thats all. Heck if you had the jumper harness i would lend you the ecu. You could test and see if it was a feasable option. Just and idea. And the vx and hx are both very simmilar engines both and the only vtec e in north america.

[turbovr41991]

I had my best trip home from work yesterday. 67.53 mpg! It was nearly a flawless trip. No traffic jams or unnecessary stops. EOC at ideal times to stage the 2 mile reset for low rpm lean burn. Still seemed surreal to be up that high! I am not sure if wind was pushing me or what???
It did not last though as my trip back into work this morning was back down to 55 mpg. :/

Originally Posted by Rusty94cx

No i spoke to them also I'm not sure that you'll be able to use your scangauge? ie its an obd1 ecu.

You are right. I don’t think I can use the Scan gauge after this which will suck… I guess I can get used to the factory tach, get a vacuum gauge, and an air fuel gauge to monitor things.

[turbovr41991]

I guess it has been a while since I updated. I got sick of the picky lean burn and went to a tuned ECU. Mid 50's is effortless in 5th gear. It is sweet. Toss in some hypermiling and I can easily get mid 60's to a tank. Best 10 mile run was 85+ where my previous best was 75 mpg. Best full trip to work was 75 mpg where my previous best was still in the 67. This was far from a perfect run, so I am thinking there is alot more potential too.

Also, got a "tunerview 2" to replace the OBD2 scan gauge. I displays 8 things instead of just 4. Preaty sweet along side an MPGuino. It even matches! (now I just need a bigger MPGuino display....)

[slownugly]

Does that new board work with a factory obd1 ecu or do you need to be running tuning software like hondata or Neptune? I looked it up pretty neat

[turbovr41991]

Not really sure on a stock ECU. This one is running on Neptune. I know they sell a variety of cable options with the LCD, so it could be used with several different options. They also have larger and smaller displays too.