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[PhilStubbs]

93 eg coupe with a vitara z6 and stock distributor

so, i got a crane external coil with MSD cap hoping i just had a weak stock coil for what seemed like spark blowout at the vtec point.

i installed the new coil soldering and heat shrinking the connections and now my tach is jumpy and the higher i rev, the less it reads. once im above 3500rpm, it pretty much drops off to nothing. car runs fine, but exactly the same as before so the coil didnt fix the problem.

anyway, now that its there i might as well keep it, but i cant figure out this tach issue. i did notice that if i turn on the headlights or hit the brakes that it gets better, but not completely. seemed like a ground issue to me. i ran a dedicated ground wire to the distributor with no change. is the negative wire to the coil supposed to be grounded to the housing or something? i wonder this since the stock coil is bolted directly to the housing.

[92CXyD]

Are you running an MSD/Crane box?

If you are who are running the tach?

Did your car come with a tach (EX/Si/some LX) or w/o (CX/DX)?

[PhilStubbs]

car is an ex, came with a tach. no ignition box, just an external coil in place of the stock one and thats the only change. put a stock distributor in it and all is well, except the miss at the vtec point. that doesnt chance either way

[Joseph Davis]

Ignitor synthesizes tach output.  Sensor ground problems can also cause tach problems, as well as running problems.

did notice that if i turn on the headlights or hit the brakes that it gets better,

Right.

[PhilStubbs]

I ran a dedicated ground to the distributor with no change. Any suggestions on where else to try adding a ground? I have all of the stock grounds still. All have been checked and cleaned even if they looked fine

[Joseph Davis]

What does a dedicated ground to the distributor have to do with a bad sensor ground?

[PhilStubbs]

I assumed the distributor didn't have an adequate ground making the tach jumpy. The ground also added to the whole head.

Is there any benefit/problem with connecting the coil negative wire to the distributor housing. I have a VERY minimal understanding of electricity. My knowledge stops at knowing connections need to be solid and grounds are super important. 

[Joseph Davis]

I assumed the distributor didn't have an adequate ground making the tach jumpy.

It's bolted to the engine itself, if that's not a good enough ground then you've painted everything in rubber.  For the third time.  Clean your sensor ground, if that doesn't fix it try another ignitor.

Is there any benefit/problem with connecting the coil negative wire to the distributor housing.

Aside from it having battery voltage applied to it in order to charge the coil?  No, I see no problem with you creating a short to ground in your car.

[PhilStubbs]

The block and tranny have been painted, but everywhere metal touched metal I used a die grinder with scotchbrite pad to clean it. I also have pulled every single ground off and cleaned in the same mannar. If a wire bolted to the body or engine/tranny it has been taken off and cleaned no matter how clean it looked.

[kgx]

Is there any benefit/problem with connecting the coil negative wire to the distributor housing.

benefits? i suppose it will give you an ignition fuse that blows every time you turn the key on to chase after instead of a jumpy tach.

the igniter grounds the coil to charge/ungrounds to fire it. the coil always has 12V present whenever the ign is on.

how long are the wires to your coil? what gauge wire? are they near the spark plug wires at all?

[DmC]

Just change the fucking ignitor and be done with it.

[Joseph Davis]

Just change the fucking ignitor and be done with it.

He ran a ground to the distributor, and now is confused.  What should he do?

[DmC]

Just change the fucking ignitor and be done with it.

He ran a ground to the distributor, and now is confused.  What should he do?

Buy a Vdub?

[PhilStubbs]

You couldn't give me a VW much less actually pay money for one


This problem came up with the coil install. How would that be the ignitor? Stock coil = tach is fine, external coil = tach jumpy.

The wires going to the coil are about 10" long. I'm not sure of the gauge but they came with the coil. Should be plenty big enough. They really aren't near the plug wires, they come out where the rest of the wires come through the distributor and go straight back.

[Joseph Davis]

What controls the coil = ignitor.  Different coils draw different amounts of current at different rates and if what charges it can't handle the coil that loads it a little more = ignitor.

IDK, if you'd asked me what caused this two years ago I would have said ignitor or thermo ground.  If you'd asked me five years ago I'd say ignitor or thermo ground.  Twelve years ago, uhm, I'm going to go out on a limb and say ignitor or thermo ground, because it was common knowledge then, too.  If you'd asked me fifteen years ago I would have told you FUCK YOU I wasn't into Hondas.

Maybe you should ground the distributor to the chassis?

[DmC]

I'm beating a dead horse posting this JD put an exrta nail in coffin. Ignitors are sketchy bitchs they want to fail you gave it a reason it failed. get a new one or like any other broke dick honda guy such as myself would do is go to my ditributor pile and pull an ignitor from one of those. If you don't have a distributor pile call you other guy who does. If you own a honda distributor piule is a must though. Oh yeah and make sure you wire wheel and scitch brite that ground to the distributor.

[PhilStubbs]

I have another distributor that I know is good, just can't seem to find it after moving. I guess this pile will just sit in my garage till I find it

can you explain why the headlights being on makes the tach work better? That is what has kept the ground idea in my head

[Joseph Davis]

can you explain why the headlights being on makes the tach work better?

Different coils draw different amounts of current at different rates and if what charges it can't handle the coil that loads it a little more = ignitor.

It's related, think about it.

[PhilStubbs]

I'm not seeing it yet, but I'm going to put some thought into it. I like to understand why I'm fixing something rather than just throwing parts at something. 

[Robb]

I'm not seeing it yet, but I'm going to put some thought into it. I like to understand why I'm fixing something rather than just throwing parts at something. 

I was gonna give you the facepalm but you seem like a super guy who really doesnt understand. 

You new coil has higher demands on the ignitor than before, the voltage/current in the ignitor is now compromised because it cant keep up with what the coil wants, so the tach which is sampling from the ignitor is seeing the ups and downs in voltage that normally would be consistent.  Thats why it jumps around. When you turn the headlights on, you place another load on the system, draws voltage/current away from the ignitor and you see less variation in voltage, smoothing the tach signal out.

[PhilStubbs]

Hmmm..... Thanks. I understand how the coil could take out the ignitor, it just seemed unlikely since how the engine ran didn't change. What you say about the tach kinda makes sense. I may never really understand electrical things. I can trouble shoot relays and shit and fix problems by cleaning grounds on a regular basis, I work in a shop repairing cars for a living. I am determined to get this car back to it's past state of being reliable and making 300whp at 15psi and getting 35mpg. 

[PhilStubbs]

What's everyones opinion of NAPA ignitors? I know normally you want a real Honda part for stuff like this. I would do that but I'm changing jobs this week so money isn't exactly flowing right now and I can get it wholesale with my current job.

[Joseph Davis]

NAPA/Carquest typically carry a higher grade of electrical part than the china parts stores. 

Also, an external Denso ignitor from an 80-90s Toyota (truck/MR2/other) is electrically the same part, and are much easier to find at junkyards.  Just get the pigtail.  Wiring is simple - power, ground (through body of Toyota/Denso ignitor), signal from ECU, signal to (-) side of coil, tach feed.

[92CXyD]

NAPA/Carquest typically carry a higher grade of electrical part than the china parts stores. 

Also, an external Denso ignitor from an 80-90s Toyota (truck/MR2/other) is electrically the same part, and are much easier to find at junkyards.  Just get the pigtail.  Wiring is simple - power, ground (through body of Toyota/Denso ignitor), signal from ECU, signal to (-) side of coil, tach feed.

Good info to know. :yes:

[Joseph Davis]

NAPA/Carquest typically carry a higher grade of electrical part than the china parts stores. 

Also, an external Denso ignitor from an 80-90s Toyota (truck/MR2/other) is electrically the same part, and are much easier to find at junkyards.  Just get the pigtail.  Wiring is simple - power, ground (through body of Toyota/Denso ignitor), signal from ECU, signal to (-) side of coil, tach feed.

Good info to know. :yes:

Knowing you, you'll have five by this time next week and two wired in parallel with the stock ignitor so you can flip a sqitch between them as they fail in some hybrid of Mad Max and military-spec triple redundancy.

Just so we all know what unit I'm talking about:

[jabberwock]

I watched The Road Warrior on Saturday on Netflix streaming... Never seen it except on TV... boobies are a nice addition to the assless chaps.


Carry on..

[ratcityrex]

Good info to know. :yes:

Knowing you, you'll have five by this time next week and two wired in parallel with the stock ignitor so you can flip a sqitch between them as they fail in some hybrid of Mad Max and military-spec triple redundancy.

I just spit out some coffee......lol

So ture, so true. Russ you crack me the fuck up. Jd is on point with that statment.

[kgx]

Toyota igniter is falling edge trigger.

It also controls coil dwell internally. It'll work, but you need an RTL inverter in the trigger input, since the honda is rising edge trigger.

[Joseph Davis]

Toyota igniter is falling edge trigger.

It also controls coil dwell internally. It'll work, but you need an RTL inverter in the trigger input, since the honda is rising edge trigger.

Now I feel stupid.

[92CXyD]

Good info to know. :yes:

Knowing you, you'll have five by this time next week and two wired in parallel with the stock ignitor so you can flip a sqitch between them as they fail in some hybrid of Mad Max and military-spec triple redundancy.

I just spit out some coffee......lol

So ture, so true. Russ you crack me the fuck up. Jd is on point with that statment.

LOL      ;D