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VN 304 running rough - stumped on this!

slitt

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Hi guys
Wondering if anyone has an idea what this could be..
I fitted a VQ 5 litre to my VH, running the VN ECU and loom.
The motor started up first pop, no probs. No errors come up (check engine light)
It idles fine, but when i rev it over about 2000 RPM with light throttle it starts coughing and spluttering. Backfiring out the exhaust. On the road with more than 1/2 throttle it seems to have power, maybe not 100% smooth.
I think it is running rich as the plugs are black, but that could just be from idling it a long time.
New plugs, leads, ignition module, injectors. Tried changing the fuel pressure reg, no difference.
Set the base timing to 10 degrees.
Checked for vac leaks
The only thing I haven't changed is the coil and distributor. But I'm thinking they are ok as it idles fine and seems to be ok with open throttle.
I picked up another v6 ECU and tried that (with my memcal).
Could it be the memcal? Does anyone know what they are supposed to look like? Mine says "V8 6554" on it. Is that a custom memcal?

cheers!

IMG_9952.jpg
 

slitt

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Map sensor condition is unknown, i got it from a wreckers, it’s off a v6. Doesn’t throw any errors. Vac source is good, new hose to the front of the manifold. It runs worse without the vac connected and throws an error.

Wiring should be ok. 2 earth points in the loom, one near the alternator and one near the coil. Made sure the ignition module is earthed to the body. Engine loom has a red wire (ignition) and red/black ( battery). Both hooked up.
 
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slitt

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I just tried the timing light on while revving it.. it strobes smoothly bringing the revs up to 2000.. then breaks up uneven when the engine splutters. on all the leads..
So it's ignition..
I suppose next I'll try another coil.. what a pain - there's even less room to get to it in the vh than there is in a vn/vp
I wonder if it's the ebay $150 ignition module...
 

gtrboyy

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How did you set timing?

Also most aftermarket or copied/ebay gear nowhere near as good as factory brand items especially those modules & coils,sensors etc.
 

slitt

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How did you set timing?

Also most aftermarket or copied/ebay gear nowhere near as good as factory brand items especially those modules & coils,sensors etc.
Put it in diagnostics mode with check engine light flashing and then used a timing light and adjusted to 10 degrees.

yeah. It’s gotta be the module or the coil I reckon. Tomorrow I’ll try my old school HEI coil off the old 308.
 

slitt

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I’m not confident about that eBay ignition module either. Just a sus feeling.
 

shane_3800

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It's likely the coil it sounds just like a coil miss to me. They can idle fine then break up down low then recover up high classic coil miss.
 

slitt

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Changed the coil and it's exactly the same. Anyone have a spare ignition module in Adelaide?
 

Immortality

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That memcal may have been played with, it's not the factory sticker. If the engine is stock it might pay to find a stock memcal to test.
 
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