Sorry made a mistake about the voltage drop, it's good. Edited post

Main symptom is after starting the car, it will idle fine. Shut it off and come back in a few minutes, no start. Plugs are wet and I am concluding it won't start after it's running with weak spark and loading up on fuel and after it's shut off the spark is too weak to ignite the rich fuel mixture. When it does fire back up after sitting for a while, exhaust smells like gas. Also, the car has hesitation issues at lower rpm range.

Has weak/missing spark. This is the only conclusive problem I can find, but can't find the problem causing it.

It's a D16Y7 (96 LX) 240k miles. Having trouble chasing it down over the past few weeks.

The down low on what has been done:

-stock fuel psi numbers and fuel psi reg. checked
-close to stock compression numbers (between 179-192 across the board)
-verified injectors pulsing correctly (also just had them ultra-sonically cleaned and flow-benched)
-ignition switch checked out (even bypassed it completely, and still symptomatic)
-PGM-FI relay checked and re-soldered (was good to begin with but did it for preventative maintenance)
-plug wires tested good, even swapped in a new set in case
-distributor has been replaced with new
-tested and tried 3 different coils (all testing good to begin with, and two were new)
-tried 2 ICMs (both verified by AutoZone, one new and one original)
-checked continuity for the distributor Hall Effect sensors to the ECM and they're good
-swapped in another computer and still same weak/missing spark
-replaced CKF sensor
-timing is set correctly at 12*
-all engine sensors have 5V reference
-battery terminals are clean with good connections
-grounds verified including the thermostat housing ground, and remade a few grounds with bigger copper wire and copper terminals, even ground the paint down and liquid electrical taped over the connections to chassis
-new plugs, stock NGK replacements, gap @ 1.1mm
-replaced ECT sensor
-IACV cleaned and tested
-MAP, IAC, TPS all verified 5V reference and correct output readings to OE spec
-New Honda cap and rotor

Problem started before I did any of the things above, so anything that's listed above is NOT a cause.

No mechanical problems at all. Car is in good repair. Any help would be awesome. I am pretty knowledgeable with a good tech background and this is giving me a run for my money. I have even stumped friends/colleagues with good tech experience and they have no clue either.

 

13.3V at the distributor seems normal. Cars generally 'actually' run on 12-13v, not the 14.x your alternator will put out.

I notice your list doesn't include spark plugs. Have you tried changing / checking those yet?

 

To add to what switch said, don't use fancy spark plugs. Some people have had trouble with the multiple side electrode ones. Try a set of stock NGK conventional ones.

I agree that's a normal voltage. The ignition is designed to fire even with less than 9 volts which it has to do while cranking. Take cap off and try to jump sparks from the coil output to a grounded test wire. The sparks should jump 1/2 inch or more. Do this both when it is working normally and when it won't start. These coils can be blown or weakened by firing into an open circuit, such as when disconnecting plug wires to check for dead cylinders (disconnect the fuel injectors instead). Ohmmeter tests of a coil generally mean nothing, they have to be tested by live fire. Have you replaced the cap and rotor? Make sure the rotor screw is secure.

Check the grounds, particularly the ECU ground wires on the thermostat. Supply voltage is one thing but systems also have to be grounded. Measure the power and ground points on the ECU (while plugged in and running) and confirm they are all powered and grounded.

Make sure the vacuum compensator hose on the fuel pressure regulator is connected to the manifold.

You could also have a MAP, TPS, IAT, or ECT sensor that is out of spec but not far off enough to throw a code. There are no codes, right? Scan with an OBDII it can provide more detail than the test jumper / blinking CEL test.

 

I edited my original post because of a mistake. I am seeing ~14.3V at the distributor.

Yes, I have been through a few sets. Gap @1.1mm stock NGKs

Yes, but the ignition is designed around operating at normal voltage (what the alternator puts out) which is around 14.5V. Yes, it will start and run on less but that's not normal operating conditions). A 1.3V difference would be a lot when you consider the other end of the coil after it's been multiplied, and that's a lot of missing spark intensity.

 

^partial response in my previous reply

Thanks for the good info, but I have covered all the normal stuff. Towards the bottom of my list, in the first post, I listed that grounds were checked/verified and also cleaned up (with new ground wires made and soldered terminals), and thermostat housing ground checked specifically. Also added that I've been through a few set of new NGK stock replacement plugs. No codes, verified with my diagnostic software/scan tool. Sensors have been checked for 5V reference and also correct readings (all factory spec). I have tested the coils hot also. Two were new coils. Had a new Honda cap and rotor on it, distributor was later replaced entirely. All this and no change. Also looked at it with my scan tool and all sensors are operating in the norm other than the O2 because the car is running rich, and it's obviously going to show that. I will say the O2 did seem to have a slow response but that wouldn't effect spark intensity, just timing advance/retard and injector pulse width.

Link to spark plug test video:
Missing Spark - YouTube

Link to MAP sensor test video:
MAP Sensor Mechanical Vs. Electrical Comparison - YouTube

Thanks for the input though. Please don't take any of the above response as me being cocky, just telling the story.

 

And here is results from most of the tests I've done

-Battery:
Ignition off= 12.65V
Idle & no accys.= 14.45V
Idle & h-lights= 14.35V
Idle & all accys.= 14.27V
Static engine off after idling= 13.43V

-Tests: At Idle and Operating Temperature
ECM Connectors:
• D connector 16P, terminal=(D**)
• C connector 31P, terminal=(C**)
o MAP: at sensor with terminals connected
(D3) Red/Grn= 0.87V to ECM
(D12) Grn/Wht= 1Ω to ground
(D?) Yel/Red= 5.0V from ECM
o TPS: at sensor with terminals connected w/ TB closed
(D11) Grn/Blk= 1Ω to ground
(D?) Red/Blk= 0.5V to ECM
(D10) Yel/Blu= 5.0V from ECM
o Distributor:
Blk/Yel= 14.27V
o Injectors:
Blk/Yel= 14.30V

-Distributor Housing Sensors: Engine off/ Ignition off (350-700Ω @68*F)
o Crankshaft Position Sensor (CKP)
o Top Dead Center Sensor (TDC)
o Cylinder Position Sensor (CYP)
o CKP:
(C2)2 Blu: 1: 417Ω
(C12)6 Wht: 2: 400Ω
o TDC:
(C3)3 Grn: 1: 421Ω
(C13)7 Red: 2: 404Ω
o CYP:
(C4)4 Yel: 1: 417Ω
(C14)8 Blk: 2: 401Ω
o Legend- Resistance across each sensor’s corresponding wires:
o 1: At distributor connector, disconnected from main harness
o 2: At ECM connector, disconnected from ECM, connected at distributor


-PGM-FI Relay:
o Bench tested using a 12VDC battery (measured at 12.37V)
o Resistance across terminals after relay is energized:

o Before re-solder:
Relay #1: Injectors
• Terminal energized= Terminal measured/resistance:
#5 = Pos+ #6 1.8Ω
#3 = Neg- #7
Relay #2: Fuel Pump
• Terminal energized= Terminal measured/resistance:
#6 = Pos+ #4 0.4Ω
#1 = Neg- #5

o After re-solder:
Relay #1: Injectors
• Terminal energized= Terminal measured/resistance:
#5 = Pos+ #6 0.00Ω
#3 = Neg- #7
Relay #2: Fuel Pump
• Terminal energized= Terminal measured/resistance:
#6 = Pos+ #4 0.00Ω
#1 = Neg- #5

-Coils: Tested off vehicle

o Primary= A(+) and B(+) 0.63-0.77Ω @68*F
o Secondary= A(+) and Secondary terminal 12.8-19.2k Ω @68*F
Tec (original)
o Primary= 0.7 Ω @54*F, 0.7 Ω @71*F
o Secondary= 15.93k Ω @54*F, 16.27k Ω @71*F
Cardone Distributor coil (new not reman)
o Primary= 0.7 Ω @54*F, 0.8 Ω @71*F
o Secondary= 16.01k Ω @54*F, 16.18k Ω @71*F
BWD (new)
o Primary= 0.7 Ω @54*F, 0.9 Ω @67*F
o Secondary= 15.67k Ω @54*F, 15.49k Ω @67*F

-Plug Wires: 25k Ω max @68*F

Cylinder # (4) (3) (2) (1)
o Super Mag (Old):
@47*(k Ω) 0.86 0.90 1.10 1.21
o NGK (New):
@47*(k Ω) 3.47 4.10 5.12 5.79
o Xact (New):
@50*(k Ω) 6.23 6.27 7.84 8.66


-Injector Flow After Professional Cleaning: cc/min @43.5psi

o Cylinder # (4) (3) (2) (1)
189 190 186 188

-Fuel Pressure Test: Operating Temperature

o Static: 44 psi
o Idle: 36 psi
o Fuel Pres. Reg. vacuum hose disconnected: 46 psi

-Compression Test: 250 rpm and wide open throttle (before and after cylinder head rebuild and head gasket, all Honda parts, 0.012” machined off head)

o Cylinder # (4) (3) (2) (1)
o Initial: 197 176 184 176
o After: 167 157 160 164
o After 2k miles: 192 187 179 187

Nominal: 184 psi
Minimum: 135 psi
Maximum Variation: 28 psi (~15%)

 

So now I finally got CEL codes....P0302, P0304, P1300. I know what they mean, cylinder 2 & 4 misfire and Manufacturer control ignition system or misfire (multiple misfire). Question is that I have a new distributor on it (got it that it's not OE but it's new and not reman), new plug wires, new OE NGK plugs gaped @1.1mm and all my grounds are good. Had the ICM in the new distributor tested by AutoZone and it passed three times. Have correct voltage at the distributor. New coil has tested good but I am still getting really weak erratic spark. I am putting the OE distributor back in with another new (different) coil, the new ICM, Honda cap and rotor, and see what I get.

Any other troubleshooting ideas?

 

Are you testing the spark at the coil output? The plug wires are the weak link and there's really no way to tell they're bad by looking or measuring resistance (since it's the insulation that fails not the conduction). Some aftermarket wires end up being total junk right out of the box.

Also if the valves are adjusted too tight, they will not close fully when hot, this causes loss of compression of course leading to bad idle and hard starting.

 

The spark will jump pretty far, even with the plug wires. I could get it to jump to a ground by well over and inch or more. I've tested multiple plug wires. OE (what was on the car already), a new set of NGKs, a new set of Xact, and a used set of SuperMag wires I still had from a while ago when I put a new Honda set on for normal service(SuperMag actually measured the least resistance of them all 0.86-1.21kΩ from cyl. #4-1). None of these, however, measured greater than 9kΩ with 25kΩ max OE limit. Swapping different plug wires made no difference in spark intensity.

Valves have been adjusted for normal maintenance. I set them right in the middle of Honda spec, I think it was 0.008/0.009in but can't remember off the top of my head which one was int/exh. Whatever the clearance, I set them in the middle, and even went back and double checked clearance after 1k miles to make sure they didn't move. I torqued the adjustment screw lock nuts down also, think it's something like 15 ft/lbs, I checked my FSM when I did it though.

 

Forgot to mention I was going to swap the OE distributor housing and various new parts back in because I already have them.

If I don't get a change from this, I am going to return the distributor as defective and swap it out from a new one. If I still don't get a change, I am going to disconnect my alternator charge wire to the battery and test the alternator for AC voltage/amperage output because I know if it's getting ready to go see Jesus and the diode pack is failing, it will do all kinds of weird crap to the electrical system. I haven't tested the alternator in the car yet because it's kind of a pain to get to, but that's next.