no spark!-I'm stumped!

[squirrl22]

95s14 w an s14 sr20det engine/manual transmission swap, professionally done wiring harness. Was running (but really rich- exaust looked like a diesel) then suddenly stopped. Cranks over great, fuel pressure is perfect, pulled the CAS and turned it by hand, injectors are firing. Pulled the spark plugs- wet with fuel. Cleaned them, checked the gap-ok. Stuck the plugs back into the coil pack, grounded the plugs- no spark! -put in new plugs- still no spark!Pulled the ECU and the ignitor chip, swapped 'em into a buddy's s14 sr20det- ran beautifully- so, not the ECU or ignitor chip. Checked the positive and negative wires to the coil packs- perfect- lots of electricity on the + side, , excellent continuity on the ground side. Double checked the grounds- all good.

Any help out there? If it's not the ECU, not the ignitor chip, not theCAS, not the + or - going to the coil packs, what could it be?

[kooboi]

i had the same problem, i went bak home, the car was fine, went up took a shower came bak down, the car wouldnt start, then i took it 2 a shop, from wut he said was the starter relay, ppl who installed my alarm had messed w/ some wire n caused the problem.

hope this helps

[squirrl22]

i had the same problem, i went bak home, the car was fine, went up took a shower came bak down, the car wouldnt start, then i took it 2 a shop, from wut he said was the starter relay, ppl who installed my alarm had messed w/ some wire n caused the problem.

hope this helps

So your car would crank over, but no spark, and it was the starter relay?

[Hijacker]

There's no such thing as a starter relay on 240s. There is a clutch interlock relay on manual model cars that sends power to the starter, but auto cars didn't have that relay. The inhibitor switch acted as the relay.

I would start checking the grounds.

If you're looking at the plug as:

1 2 31 is the grounded source for the coil pack's secondary coil (-)2 is the 12v supply for the primary coil (+)3 is the ECU ground complete for the primary coil (E)



I would do a continuity check from the coils to the ECU to make sure that's working fine. Then do a power check to make sure the 12v supply is working fine. Then double check the ground on the back of the head as that what's grounding the secondary coils.

Look on page EC-121 of the S14 SR FSM and you can see exactly what I'm talking about with the grounding and power routing of the coil packs.

[squirrl22]

Thanks!- my car is a manual- no problem cranking, just no spark.I've checked the coil pack +12v- it's fine,I've checked the continuity to the coil pack - ground, it's fine too- I'll check the continuity between the coil pack and the ECM- I've got the diagram up on my screen.If there is a problem with the continuity, maybe I have a problem in the ground or in the + going to the ignitor chip?

[Hijacker]

The + doesn't go to the ignitor. It's the 12v constant, like I said. The E goes to the ignitor (and subsequently the ECU)

I like explaining this, so I'll repeat it again.

There's a primary and a secondary coil in the coil pack. The primary is always hot until something breaks the continuity of the circuit. The secondary coil is wound around the primary and is grounded between the spark plug and the head.

Now, when you break the continuity of the charged primary coil, the power on the coil arcs to the secondary coil and it lights up the spark plug to the tune of 40,000+ volts. There's a scientific explaination of why that happens, but I'm too stupid to remember the name.

Now, the way our coils are powered is like this

battery -> (JDM cars have an ignition relay) -> Coil Pack -> Ignitor Chip -> ECU.

The ignitor chip, or Power Transistor Unit,, from what I can tell in circuit diagrams is nothing more than a resistor to bleed off excess voltage to keep from frying the ECU. Anytime you put constant voltage on an ECU part, especially one from something like a coil, you're bound to burn it up eventually. S15s and the skylines did away with ignitors by including them into the wiring for the ECU (internal power transister units)

The - on the coil pack needs to be grounded to the head so it can arc to the spark plugs. That's why I asked you to check the ground on the back of the head to make sure that it's still good. If it's come loose or the wire broke, you're not going to get spark because the secondary coil won't be grounded.

If you want to test your head ground, take a test light and bridge it across the + and - terminals of the plug. If your light lights up, you have a good ground. Then you need to focus on the E terminal and all the wiring associated to it. Also, make sure the ignitor is grounded properly as well. From the sounds of it, it just sounds like a plug isn't seated properly. You've tested the ignitor and ECU as good, you verified that you have a good 12v source, so it's either a bad plug (probably ignitor since the plug to the coil pack sub-harness is allowing the 12v supply to flow) or a bad ground.

One thing I just thought of, this could all be a CAS related issue. If it's bad, the ECU won't know when to fire the coils. It could also explain your running rich situation as well. Once you test your wiring out, start focusing on the CAS

[PhopsonNY]

Hey Hijacker...

that is really great and useful info...

Did you learn all this just by reading the Shop manual?

[Hijacker]

The coil stuff I learned off How Stuff Works and then compared it to the coil pack design. Originally I thought our coil packs were direct fire, but once I did some research and comparison, found out they weren't

[dmin180sx]

yea thanx for the info. im having the same problem. been pulling out my hair for the last three weeks trying to figure it out!

[squirrl22]

Hijacker, you are really good explaining this stuff!

I tested the - by running a test light from the - plug wire to the battery pos terminal, and it lit up. I tested the + by running a test light from the + plug wire to the exaust, it lit up. Then I ran the light from the - to the +. It lit up. So, I'm pretty confident the - and + wires to the plugs are good. The ECU and the ignitor chip I plugged into a buddy's sr20det- it ran perfectly. So I'm pretty sure it is not the ECU or ignitor chip.

I stuck in new plugs, still no spark.

As far as the CAS, I did pull it, and spun it. I heard the injectors firing off, so I assumed the CAS was doing it's job. Maybe it's only firing the injectors, but not supplying a signal to the ECU for the coils/plugs?

[Hijacker]

I think you have a problem with the connections for your ignitor, ECU, or the coilpack subharness. Look inside each plug for all of those to make sure they're not corroded. Also make sure that the ignitor's ground is functioning as well. It's the black wire coming out of the 5 pin plug (middle one I think).

Other than that, a continuity test from the coil plugs to the ECU plug is the only other option then. Beyond that I'm stumped as that would be everything involved in the ignition system. Except for the coils themselves, and I don't see all 4 going bad together like that.

[squirrl22]

With your description- yep, it's the middle black one-I've I located the ignitor chip ground, tested it with my light- ran the other wire to the + bat terminal and it lit up, so the ground to the ignitor chip is good.I pulled all the connectors to the ECU, and ignitor chip, and coilpack harness-they look clean and shiny-

Are there any fuses between the ECU and the coilpacks? Or, a fuse or relay that could prevent the ECU from sending a signal to the coilpacks?

Nothing left but to check the continuity from the coil plugs to the ecu plug. -I figure I can rig up a 6v battery/bulb/10ft wire combo to test the continuity of each wire going from the coilpack harness plug all the way back to the ECU plug.

[Hijacker]

It's pretty much a straight shot from the coils to the ignitor to the ecu. The only relay that's involved in the system is on JDM cars, and it's for the 12v supply

[bgsr240]

This a very interesting thread to me as I have the same problem, no spark.

If you find the problem Squirrel22 please, please, please post it up.

[squirrl22]

Hopefully, my schedule will open up for a couple hours this week, and I will start tracing backwards thru the wiring. I'll keep you posted.

[drkidd22]

I swapped my SR into my 240 and took me three weeks to turn it on. Same problem here with the no spark. Do a continuity test on ALL your wiring. Make sure all plugs are tight. If you are good with schematics take a look at the FSM for the SR20. Test your Ignitor chip which plays the most important part on this problem.

This is a pain to figure out. My problem was in my wiring hardness. Some pins were dirty and I didn't solder or shirnk wrap my connections at first. So I Took my hardness out, tested every single cable and component I could. I cleaned my connectors, solder and shrink wrapped my plugs.

I know your hardness was made by proffesionals but that doesn't mean they are perfect. So just check everything. Using the schematic test the ECU for power, make sure it's getting the juice it needs. The injector test you did is good but does your fuel pump turn on when you place the key on start?

[al]

Also make sure all the wiring is right, two of the cas signal wires are black and can accidentally be connected to a ground instead. Definitely check the wiring from the ecu to the ignitor to the coilpacks, maybe they ran the wiring through the ignitor the wrong way? Make sure the fifth wire on the ECU side of the ignitor is properly grounded. That would also cause it not to start.

Make sure your timing is correct! If it's off by more than a couple degrees it will just crank all day.

Are you running stock injectors?

[CLOCKWORK420]

Did you ever get the "No spark" issue figured out?

[lilpiton]

I have the same problem with my sr right now. So please let us know what did you end up doin with your problem just like you said you will keep us updated...

[CLOCKWORK420]

Hey Squirrl22. Get at me dude. Im sure you figured out the NO SPARK issue by now..... What was it?

[PyR0NiAk]

Dude hasn't posted since August of 2008. Gone user is gone.