Treewilly

Hello all,
I haven't posted on here in forever, so I'm going to try and keep this short and to the point.

I have a 93 civic dx, with a swapped d16y7 with a z6 head. I have not obtained a Vtec ecu or controller yet.

Since about November of 2013, my car has been sparatically misfiring and running like ****. The problem is directly correlated with how much throttle I give it. If I drive the car like an absolute grandma, it will run fine. The problem started happening every once in a while and now is a constant problem. Now, sounds like a simple tune-up, I know. I am a 20 year old with 6 years mechanics experience and a lifetime of turning wrenches. However, this problem remains mysterious. Here is a list of things I have tried:

Cap, rotor, plugs, wires, coil
Complete distributor assembly
Fuel filter

I have tested extensively for a blown head gasket
Have unplugged tps to see if that was the problem
Checked valve lash
Checked engine grounds

Another weird symptom: speedo waves up and down while engine is sputtering.
This problem has me frustrated beyond belief.

Please, lend any idea you may have .

ej1995

Last time I saw somethig like that, there were wires rubbed bare in the harness and touching and grounding out.

Treewilly

That's what I am afraid of. Can't find any spots in the harness that look questionable though.

rice a roni

iTrader: (1)

Does it do it at idle?

Treewilly

It does not do it at idle. Also no flash codes except for one that has been there forever for the IAT. Also it's been overheating on me sparatically,just happened when I was getting up to speed on the highway.

TomCat39

If you've ruled everything else out like it seems like you have, I'd begin thinking you may have a crack somewhere, or burnt/bent valves or something of the like.

If it's not vacuum related, Head Gasket related, IACV related or PCV related, or electrical related, then I would think the only thing left is a crack in the head or block.

Being you haven't swapped the ECU yet, could also be that. The capacitors are known to get weak with age. Every site that I've looked at that chips Honda ECU's state they replace all the capacitors to maintain reliability.

Treewilly

Thanks for the reply. What your saying makes sense but without pulling the head there is no way to know. So that may be in my future.

Another development: put a timing light in it yesterday to make sure it was ads ancient with throttle, and found that all four plug wires are occasionally missing spark. Obviously this is my problem. What could cause this BESIDES the distributor components??
Main relay maybe??

TomCat39

Not really sure, I would think either a faulty ICM or an ECU slowly giving up the ghost.

I really am not as familiar with all the systems to know if there is anything else in the system that could cause periodic loss of spark.

I've heard the ECU will keep the engine running even when it looses the cam sensor input which I've read happens periodically due to Honda distributor design. tiny signal next to huge magnetic fields of the coil all in a relatively small amount of space.

Maybe that aspect of the ECU is growing weary?

Honestly, I was hoping one of the other more experienced folk here would be able to shed some light or insight onto your problem.

The other possibility was already mentioned but that means a harness trace to see if there is any exposures and or partial breaks. No fun.

After rereading, had forgotten about the overheating issue. ICM and ECU probably doesn't make the car overheat. Not sure if the overheating and the grandma only running are related. Sounds more and more like a crack.

QuinnL414

Did you ever figure it out I know its been years but having very similar issue. Currently Cylinder 3 and 4 are misfiring on my D15Z1 95 civic all spark plugs spark, fuel injectors inject, and just replaced distributor cap rotor and previous bad o2 sensor. Car has also been overheating aswell but i believe this is from my radiator having a bad leak. The misfires happen similar to you when i throttle more then grandma speeds car has very bad hesitation getting moving and the misfires happen every time i drive it. Also the tach bounces up and down from 1.5-1.8 rpms during idle. Next I plan on looking at compression, timing belt, and ecu but iom really not sure where to look this is my first ever honda and im pretty new to working on cars Hopefully some of yall still active on here and could reply with what worked for you on a similar issue.