blaheyt

Hey all,

So I'm currently wiring up my LS swap, however I'm still awaiting injectors to arrive. Everything is wired in, however injectors aren't plugged in due to not currently having them.
I'm just wondering if this could be why I'm not receiving spark? I'm getting an RPM signal so crank sensor appears to be good, I also have power and ground at the coil harness, including 12v when cranking.

Is there anything else which could cause a no spark that I should be looking for? or is it normal to not receive spark with injectors unplugged?
Just trying to diagnose everything from what I currently have. Everything else seems to be working via my scan tool.

Thanks in advance!

ls1nova71

iTrader: (4)

You should still get spark. Have you verified all the ground data are on and good?

blaheyt

Thanks for the reply.
Okay so I've done some probing, two of the pins are constant ground, regardless of weather the key is turned, ecu on or off. Does that sound correct? It looks like it on the schematic to me? I'm also getting power to the connector, yet still no spark? I'm getting 12+ v when I put a multimeter through the plug terminal ground and positive.

How would I go about checking the ground data? Probe them whilst cranking and check for voltage? They are grounded from the ECU side by the look of the schematics, so I gather I'd hook a multimeter up to the power side and ensure there is power coming through the plug?

Thanks for the help, greatly appreciated.

ryeguy2006a

iTrader: (27)

I could be wrong, but I've never heard of a switched ground? I believe all grounds are constant, so I'm pretty sure that's not your issue. What ECU are you running?

blaheyt

Thanks for the reply. By switched ground, I mean the ECU pulls it to ground? However after further looking at the schematics, it looks like the ECU pulls the injectors to ground and provides the coils with power.
With the coils, the power appears to be supplied by the IGN on and is constant. One ground is supplied by the block and the other by the via the ECU all of which I have. Power remains on even whilst cranking. I don't appear to have anything coming from the other 4 wires in the coil harness on either bank? So no signal coming from the ECU commanding the coils to spark?

The ECU is out of an 05 gto!

Sorry for the confusion!

Thankyou.

ryeguy2006a

iTrader: (27)

The ECU will provide the ground signal for both the injectors and the coils. The 12v signals should be either switched or constant depending on what you are looking at. As for the ECU, have you had it flashed by anyone for stand alone?

pdxmotorhead

Is the security stuff disabled in the ECU?

blaheyt

Thanks for the info.
Yes the ECU has had the VATS disabled. VATS are showing as inactive on my scanner.

Other than the obvious, powers and grounds, what parameters does the ecu require to enable spark? Would the neutral safety or clutch switch factor into these as well? Like if something is defective in that circuit and it sees it as in gear or clutch engaged it wont provide the signal to turn spark on?

Thanks!

pdxmotorhead

I had trouble getting the passenger side of my Holley terminator setup to fire, I removed the ground wire from the head and cleaned the contact position and put it back on, dab of electrical grease and tightened it firmly. Used a serrated copper lock washer under the bolt on top of the connector loop. Fixed the problem.. The rebuilt motor had been sprayed with a very thin cote of some kind of sealer.. Was not grounding..

ls1nova71

iTrader: (4)

Neutral safety and clutch switches won't keep the engine from getting spark, they just control power to the starter. Basically you need power, ground and a crank signal to get spark. How are you checking for spark?

blaheyt

Got the spark problem sorted thanks guys. Turns I had a voltage drop caused by my negative battery cable. Swapped it out and now I'm getting spark!
Still a no start however, although I think that could possibly be to do with my IAT sensor. It's reading at -39 regardless of weather it's plugged in or not. Would this cause a no start? Fuel is now plumbed in and 59psi is showing on the gauge! Will try and source a new IAT sensor tomorrow and hopefully it fires to life!

Many thanks for the help.