Realize the full Performance/Economy Potential of a Honda Civic VX

[GasSavers_grasshopper]

You are correct with the DFCO and the RPMs for it are listed in the helms manuals. If I knew how to post images I would, but here is the info taken directly from the manual:

During deceleration with the throttle valve closed, current to the fuel injectors is cut off to improve fuel economy at speeds over the following rpm:
D16Y5 engine (M/T): 850 rpm
D16Y5 engine (CVT), D16Y8 engine (USA M/T): 920 rpm
D16Y8 engine (USA A/T), D16Y7 engine (USA A/T): 910 rpm
D16y8 engine (Canada M/T), D16Y7 engine (Canada): 990 rpm
D16Y8 engine (Canada M/T): 1000 rpm

On a side note, I have the equivalent engine that you have except that I have the correct ecu for the engine. Unfortunately, I got the engine with an automatic intake manifold - meaning I'd have to convert the IACV and EGR wiring.

[suspendedhatch]

Regarding the Above Post
According to a spanish language Helms manual I downloaded, the factory DFCO cutoff for the D15Z7 is 1200 RPM. It also confirms the specs for the other engines as reported by grasshopper. I have been using 900 RPM as my DFCO cut-off and it has worked fine. RPMs don't drop past my idle target when I decelerate. The AEM EMS has a high idle vs VSS and a delay setting that works nicely.

Thanks for that info. I tried looking for the VTEC-E engagement parameters for the Y5 in the Helms but did not see them. They're listed for the Z1 and Z6 in the fifth generation Helms... so I don't know why they skipped over it for the sixth generation.

It should give the

Engine Temp
RPM
and for engine load it just says it varies

So is your ECU for automatic or manual? If it's for a manual then you can drill some holes into your intake manifold to allow for a conventional IACV. And you would need a manual trans throttle body.

Where did you get your ECU?

Post up a build thread and link it!

[suspendedhatch]

Up until this point I have been running the stock ignition setup since my MSD DIS4 was bad. The stock coil is bad and I've been using a coil dwell workaround in the mean time which has made the car run decently but with some small problems with idle. My HC's are higher than they should be according to my smog check which I haven't yet passed.

Well I went to California and emptied my garage and brought everything to Utah. I had two spare Honda coils. I tested them with a voltmeter. One was blown, the other had just a hair too much resistance. So I installed it, set the coil dwell to the correct setting, and fired it up. It had a lot of trouble starting up but it ran excellent.

The funny part is that when I took off the distributor cap, there was shredded plastic all over the distributor housing. The little screw worked it's way out of the rotor and spun around scraping the base of the rotor and wedging itself into the cover. One edge of the rotor was bent and burnt looking. Oil is leaking into the distributor so I will have to change the O ring.

The spark plugs were black. #4 was very black and the others were black but with brownish white at the tips. These were NGK's meant for a B16. It's all we had when I did my swap. They are only a few months old but had a couple thousand miles on them. So they're probably the wrong heat range or it's just because I don't have the engine tuned properly.

Scottie lent me his AEM Twin Fire, so I wired it up with the CBR600F4i coils and some Autolite screw cap spark plugs (ugh, I know. But I'll switch to the Denso or NGK Iridiums AFTER I have this thing tuned properly). I had an extremely hard time finding any info on how to wire and configure this to the EMS. My EMS is a 30-1000 box, the oldest box with only 1 extra coil output. So I have to wire it for waste spark, which isn't a bad thing.

I wired the 1&4 in series and the 2&3 in series as per this diagram I found. Started excellent but above 2400 RPM it just breaks up. Makes no power at all. Idles fine as long as the IACV isn't intervening. When it has to intervene, it hunts badly. Tach reading on the cluster is way too low, but seems to be accurate in the EMS? I wired the tach output from the twin fire to the EMS and there was no change.

I tried a couple different combinations of settings in the EMS and nothing changes. I tried changing the spark teeth from 6 to 12 and then 24. I tried ignition tooth 1, 3, 6, 8 at 0, 3, 6, 9 and 0, 6, 12, 18 respectively. I enabled coil 1, 3, 6, and 8. Tried the coil dwell wizard CBR600F4i setting and then the "all CDI except Ford" setting. I turned off coils 6 and 8 and it made no difference.

Then I wired the coils in parallel. 1&4 are sharing power and ground, and 2&3 are sharing a separate power and ground. Blue and Gray are grounded. Still the same. Now it wont even start when I put spark teeth to 12 and ignition teeth to the lower settings.

I'm going to try calling AEM.

[suspendedhatch]

Here's my dyno graph that I forgot to post up.



The blue lines are from the first dyno pull we did. No tuning and no VTEC-E or VTEC engaged. Notice that the torque falls off rapidly starting at 4000 RPM. If you switch to 16 valves around 2500 RPM the graph climbs rapidly all the way past 5000 RPM. This is a point I try to make to people that plan to get a 3 Stage VTEC motor and have VTEC-E and VTEC engage at the same time. The ideal VTEC engagement point isn't until 5500 RPM or so for this motor. If you use a P28 ECU, it activates VTEC at 4800. So you'll have a big dip in torque caused by a late VTEC-E and an early VTEC. Not to mention that the OBD1 D-series maps have much more timing than is optimal for the OBD2 heads which are more efficient and have more quench area.

The first pull resulted in about 65 hp. The second pull (not shown) where the only change was turning both VTEC's on resulted in 110 hp. Tuning netted another 9hp at the peak, but even more impressively it raised the entire graph substantially.

Notice the big dip in power between 5000 and 5500 RPM. This is caused by my ebay CAI. You wont see this with the factory tuned intake. The huge hump starting at 4200 RPM needs to be shifted to the right. If I were to try different lengths and diameters of intake piping I could tune that dip right out. No off-the-shelf intake is going to be optimal for this engine except by coincidence due to its unusual cam.

[suspendedhatch]

Here's what a distributor-less conversion looks like:



This is the how-to article I'm working on. Don't reference this until I've actually worked out all the bugs on mine.

http://causeforalarm.thecarthing.com...ire/index.html

[suspendedhatch]

Here's the VX 13 inch rims vs the HX 14 inch rims

[GasSavers_topher]

Hope you get it all figured out man. Dyno looks good :TU:

[suspendedhatch]

I started a new VTEC-E article: http://www.gassavers.org/showthread.php?t=7282

[DRW]

Thanks for posting the dyno chart. The power looks good. Since the engine is making near peak torque at 2500rpm (91 ft./lbs ) are you able to shift early and keep the rpms low? Or does the car need a few more revs?
How's the mpg?

[suspendedhatch]

Yeah you can shift it early and cruise pretty low. Not VX low... I don't drive that way though. The JDM D15B's love to rev. Especially when paired with a VTEC tranny (shorter gearing) and a 11lb flywheel. I can't help but to blast the RPM's up when I need to get up to speed. It seems like as soon as you give it gas it goes to 4000 RPM. This engine is a lot of fun.

Actually that's how my g/f drives. I have her drive while I tune it on the laptop and I noticed that the way the follow cell moves around the calibration maps is very different than when I'm driving. She shifts early, usually just as the engine is about to make power. Drives me nuts.

The guy that tuned the engine (Scottie) shows off the dyno graph to other D-series drivers. It's very surprising for nearly stock and the torque curve is awesome.