enrique

I know where the RMP signal is on the ecu. is that a good spot to pull from? if not where can I get the signal from? thanks

NZConvertible

There's a short wire hanging from the trailing coil's loom with a bullet connector on the end. This is for connecting a diagnostic tach, and will work for the dyno. Set to 4-cyl.

enrique

happen to have a diagram of that?

NZConvertible

Just look in your engine bay. It's easy to find.

enrique

thanks for the help you are a great asset to this site.

just wanted to make sure this was the wire

White_FC

Umm... no thats your leading coil pack, you need the one from the traling coil pack for the signal to work right on a tach.

enrique

would that be the white wire with a blue stripe towards the firewall?

White_FC

I can't be bothered walking outside to my car to check but I think its a yellow/blue wire, yes towards the firewall comming off the traling spark coil pack, it has the same bullet connector on it just like the one you have pictured.

enrique

ok that wasn't it then different style connector. I didn;t see anything else in that area.

NZConvertible

Actually, both the leading and trailing coils will give you exactly the same signal. It doesn't matter which is used.

And yes, I know the leading plugs use wasted spark, but the trailing coil tach signal wire is a summed signal from both ignitors, so the output is the same as the leading coil.

White_FC

I beg to differ NZConvertible, the tach signal on the leading coil goes crazy, giving twice the ammount of pulses it should, waste spark as you said. Somehow the traling one differs completly, the signal is 'right' on the traling coil pack test lead thingy.

Trust me , I had to get the RPM signal for my fuel only microtech from somewhere and first tried the leading coil, which gave very bad results... Would sometimes work ok but then at WOT it would jump to double than normal (does the stock ECU only run waste spark when under power??? or is it ALWAYS waste spark?)

So.... ....unless a normal tach has a completly different way of decyphering(sp?) this pulse than my microtech does.........

NZConvertible

They should be exactly the same. The tach lead on the trailing coil pack gets a signal when either trailing coil fires. So that's one spark per rotor per rev, or two sparks per rev (same as a 4-cyl). The leading coil fires whenever a leading spark is required. That's also one spark per rotor per rev, or two sparks per rev (again, same as a 4-cyl). The result is the same signal from both coils.

enrique

I put down 165 hp with 138 tq. only mods are drop in k&n and an n1.

NZConvertible

Is this on the 98 Honda Civic hatch listed in your profile?

HAILERS

I'm almost positive NZ is wrong on this one. But let me tell you a little story that just happened. To prove that the lead and trail are different I just went out to the car and put a Fluke88 on both bullets. First let me let you know I installed a Crane HI-6 Wednesday. Well I looked at the trail bullet, put the meter on rpm, read it and then went to the Lead bullet. Put the neg lead on the battery negative and the pos in the bullet. Well the reading was peculiar......then the car started to stammer. Then the car DIED. EEEEK! So i started the car up. It started and idled ok. But it seemed a touch lower in rpms. Hmmm. So I pulled a Lead wire out of the coil assy. OOps. NO as in NONE spark. Pulled the other wire on the Lead coil (stupid but desperate) and no spark.

So I looked at the Crane box and the little red light was blinking as it should when a valid trigger signal is seen. Stumped me. No spark. Engine running on trail. So I did the sensible thing. Shut the hood and watched The Daytona 24hrs for a few minutes. Gave that up and went back out and started the car. The car ran. PUlled a lead coil wire. Big **** sparks. Made a promise to God to never put my meter in a bullet on a car that has a Crand HI-6 ever, ever, ever again.

But I have a fall back. I've still got the 86na out there with no Crane HI=6. I didn't promise anything about a car without a Crane HI-6. So, tomorrow........out to the 86 to take a look.

I think they are different because a couple of years ago I installed a rpm switch for the aux actuators on a na and the signal was different b/t the lead and trail bullets.

OH. Yellow wire with a Blue stripe is the rpm signal wire on the trail coil assy.

White_FC

Yes, the signal is very different, NZ I know you say they're the same.. but mine certainly wern't thats for sure, just no one seems to know exactly why!
but! having a bit of a look on the wiring diagram I can see 3 wires going TO the coil pack and one (the tach wire) comming OUT of it.

Do you think that maybe it has some internal(to the coil pack) switch system to give out the 'right' result? where as the leading coil doesn't?

HAILERS

http://www.teamfc3s.org/info/articles/demystifying.html

Possibly something to do with the LEAD trigger firing once each 180 CRANK degrees and the Trail trigger firing but once each 180 CRANK degrees. Maybe the answer is answered in the above url where he talks about how the trail gets but one trigger signal but still has to fire two different coils in the trail assy.

HAILERS

http://www.teamfc3s.org/info/articles/demystifying.html

Possibly something to do with the LEAD trigger firing once each 180 CRANK degrees and the Trail trigger firing but once each 180 CRANK degrees. Maybe the answer is answered in the above url where he talks about how the trail gets but one trigger signal but still has to fire two different coils in the trail assy.

If I remember right the LEAD was always twice what the TRAIL rpms were.

NZConvertible

Well I'm pretty sure it was you Hailers that told me the trailing coil pack's tach wire was a summed signal. It pulses whenever either ignitor fires, so it would pulse as often as the leading one does.

If I'm wrong then I humbly stand corrected, but I'm pointing the finger at my source...

a7r

I got curious, so I went out and hooked up a frequency counter to both wires. The secondary connector did what I expected (I got like 35 Hz from it, with the tach hovering at ~1k).. the primary connector gave me a varying frequency in the range of 250-300 Hz (which might have just been my counter picking up noise).

Anyone know exactly what the primary's connector is wired to?

kmags

165 hp and 138 tq. is awesome for just a catback and a drop in filter. I wish my vert had that much power.

nonameo

yes that IS amazing....

HAILERS

***Well I'm pretty sure it was you Hailers *****

Nay, nay NewZealander, not I. I specialize in airpump superchargers, not ignition issues. It must have been that guy standing behind the tree over there that told you that.

White_FC

Or maybe it was that sheep over there behind THAT tree??
Opps a bit below the belt.. (hehe no pun intended in that one NZ.... )


But seriously now, if anyone had a schematic of the internal workings of the trailing coil pack, we might be well on our way to understanding why this straaange 'problem' occurs.

If my car was actually running i'd go stick an ociliscope on it tomorrow, but alas, its not..

Anyone with a CRO and a running FC able to take these measurements?

bingoboy

something's fishy...