Refreshed 20v blacktop first start..

[Mylesmck]

Well Lads,
I'm tryna start my engine and it kicks, but just won't "catch".... So it's getting fuel and spark, but not enough to idle or rev.

For context, it's been rebuilt with new crank, bearings, rings and gaskets. I've wired it with cops running off the oem ecu (for now, until I can afford a standalone). So it batch fires the sparkplugs which should be OK as the injectors are sequential.

Oil pressure is good, engine cranks without any wierd noises, I could feel heat on the no. 2 & 3 headers. I tried to upload a video of it trying to start but it's too big.

I'm wondering if the itbs need to be balanced... Should I do a compression test? Should I get a timing light, jumper the diagnostic plug and try to set the ignition timing?

Help!!!!!?

[Dave W]

If there is fuel on number 1 & 4 plugs, then I would look at ignition. Start with the easy stuff wiring, and pick up signal.

[Mylesmck]

Thanks @Dave W, I managed to get it to run, albeit only on 3 cylinders. It turns out it'll batch fire 3 coils, but the spark dies as soon as a 4th is connected. I can't pin it down to any one coil.... any ideas?

[Ivan141]

That sounds like it might be a power issue, firing all 4 at the same time might be causing a voltage dip that disturbs the coils? Just spitballing here though.
I've read about coils drawing up to 10A during dwell, multiply that by four and you have a very serious peak current draw that could easily pull your
voltage down, especially at the coil since your coilpack wiring is likely not specced for such high currents.
What size fuse are you running to the coils at the moment?

[Mylesmck]

@ivan141, yeah you may be right. I'm not sure what size fuse is in there, I'll have a look later. I may run a seperate battery and earth the coils directly to the block as an experiment, to see if it is a power issue. My extending of the original bt harness also included a 47pin bulkhead connector, though I'm quite sure I ran the coil feed through a 16ga pin...

[Mylesmck]

So I completely bypassed the +ve supply and ground wiring by connecting directly to the battery and engine block respectively. No change. It's either the 5v(?) trigger from the ecu igt is dipping with the addition of the 4th coil. Possibly the ecu components have degraded, or maybe the coils themselves are the issue..

[Ivan141]

I would also try some extra ground straps directly to the head (in/ex manifold studs perhaps).