300zx no spark

[cmoody2006]

ok i have no clue whats going on i bought a 1990 N/A z32 and he said the fuel injectors were bad. Well i didn't have the money for a brand new set of injectors so i got some used ones from a guy on nico. I checked all the new fuel injectors with an ohms meter and they were in the 12-15 range Most of the clips on the wiring harness are messed up but they still hold themselves in place. I pulled one of the coil packs out and put a spark plug in it. I set it near a ground and there was no spark. What could this be?

[Vilmenay]

Dude welcome to my world I've been sorting my car now for 2 months here's what I've learned.Turn the car to the on position but dont' crank it over Take a volt metter to one of your coil plugs and see if you have power in the middle lead if it's at least battery power your ecu is good. Then I would suspect your PTU. Take the cas out while it's still plugged, which is that silver round thing on the front of the the engine drivers side, take the three bolts out and spin it if you hear your injectors fire and your fuel pump prime then your injectors are good. Be sure to put it back the right way as it has a key slot inside of it. If you dont' hear the injectors tick then your cas might be bad. Also make sure you have power going to your injector plugs and that your grounds are good. Check continuity on your egi and fuel injection relays.

[cmoody2006]

thanks i'll try that and see what happens

[cmoody2006]

ok when you say take the cas out while its still plugged in what do you mean? is the car still suppose to still be in the on position?

[Vilmenay]

You'll notice that the cas has it's own harness plug, leave that attached, put the car in the on position and turn the tip of the cas you should hear the fuel pump prime and the injectors fire. If you have a hard time hearing it, go in front of the battery you should see a fuse box remove the one that says fuel then go back and spin the cas you should be able to hear the injectors fire without having to listento the fuel pump prime. Now to be honest I'm not sure how loud the injectors should tick because i could barely hear them on mine so if you can hear a subtle tick using a screw drive to your ear with the tip touching an injector head I'd say they are firing.

[DadZun]

Check your ignitors, theres one on each bank. They have a habit of dropping a cylinder (would appear like a injector fault), and when completely stuffed, not allowing a current at all, so no spark. I would check them first, as its a real common fault on VG30s. Not expensive to replace, but try to locate new parts - I recently shelled out cash for a autoelectrician to do mine, discovered on invoice that he had used second hand parts, would replace with new unless I paid a 2nd labour charge, and now 5000km later the ignitors rooted again.

[thoroughbred3.0]

wait.. are you guys talking about no spark to ANY cylinders, or just one...sorry lol i have no spark to one of mine right now and lookin for info

[cmoody2006]

Were talking no spark at all to any cylinders, anyways I haven't had time to check any of the following I'm off at college but I'll be back this next weekend or the one after. So any other input or suggestions would be greatly appreciated.

[evildky]

Check your ignitors, theres one on each bank. They have a habit of dropping a cylinder (would appear like a injector fault), and when completely stuffed, not allowing a current at all, so no spark. I would check them first, as its a real common fault on VG30s. Not expensive to replace

uh... the PTU is the only "ignitor", you have 6 coil packs and one PTU, as far as I know, the ecu would be the only other crutical part

[cmoody2006]

ok i was home this past weekend working on my z and i tired removing the cas. I unbolted the 3 screws holding it in place but i can't get it to budge. Also i unhooked the battery so it would keep a charge and not die. I had a friend of mine hook it back up and he knows jack squat about cars. Well he ended up putting the batter cables on backwards and fried the wire in the little box next to the battery. well my guess is its called a battery box. Well it drained the battery pretty bad so i recharged it after realizing what he had done. I took the fried wire out and replaced it with a new one - (I'm big into electronics so i just took it apart and soldered a new wire that was the same gauge in place and put it back together). Well now when you go to turn it over it makes a sound as if the battery is dead. Should i try the battery out of my 240 and see what happens? Also how do i Get the cas out? does it screw into place or amd i going to have to get some special tool to pull it out.

[Zwicked]

You say you are holding the plug "near" to the ground? You know it has to be absolutely grounded to the block to test this right?The PTU is a common failure when there is no spark on any plug. Can happen if the PTU is poorly grounded to the engine, or the engine itself is poorly grounded to the frame. Poor or intermittent grounds kill PTU's.Do you have the old black one or the newer silver unit?

[cmoody2006]

I have the newer one but most of the wiring is just loosely wrapped in electrical tape. on both sides of the ptu. I had it near a ground and i even had it resting on the ground. I had nothing not even a tiny wannabe spark

I'm about tempted to go and buy a new or used (working) ptu, ecu, cas, and engine wiring harness.

Anyone have these parts?

[cmoody2006]

bump

[evildky]

lol, the electrical ground, not the physical ground under your feet

[cmoody2006]

Ok you read that wrong i meant a bolt that was a good ground
Modified by cmoody2006 at 11:52 AM 8/25/2007

[cmoody2006]

So i was able to move the cas finally and I could hear the fuel pump prime up but not the fuel injectors. Why is this could it be the wiring for them or what?

[cmoody2006]

bump

[evildky]

ok, with the cas out of the car you turn it and each injector should clock, they are kinda burried and hard to hear, a screwdriver with the handle against your ear is an old trick, or you can buy a mechanic's stethescope, it's got a metal rod and diaphram on it, if you aren't getting clicking then you are either missing voltage or signal form the ecu, check for voltage at the larger of the wires going to the injector and the ecu signal is a squarewave

[cmoody2006]

I can't hear them tick even with the screwdriver to my ear. Does this mean the cas is fine?

[evildky]

the cas sends out 2 signals, one every degree fo rotationa nd one every 120 degrees, not sure which the ecu uses for what but it needs both signals, you can test with a snapon smartprobe or similar, I've heard an analog multimeter also works

[cmoody2006]

How would i test it? I have a digital multimeter/voltmeter what would i need to test