Slacker_Sam.

AU2 Falcon requires assistance

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Hey everybody. So my blasted AU is packing a shit. It's got the 4.0 intech VCT log under the hood. It was running fine but the other day it started misfiring under load. This happened after I gave it a foot full to pass some tourists in a Nissan Tiida.  

So after I got home I replaced the plugs. No change.

Changed the coil. No change. 

Changed the intake gaskets. No change. 

Changed the fuel filter. No change. 

Did a compression test & it all came up acceptable. 

It seems to run on 6 at idle but misses on throttle. I've tried to isolate it by pulling off leads whist it's running but they all cause a strong misfire when pulled off. 

I'm scratching my head....any ideas? Halp

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Can you get someone to load it up in D to recreate the misfire, while you pull leads/injectors to try isolate the cylinder.

/replace more stuff

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I just took it for an Italian tune....things got worse so I limped it home on 4 + 3/4 cyls . Then just as I got to my street it got itself together and gave me a full 6 cyls. But I don't trust it. I guess I'll put a set of leads on it tomorrow and see what happens. Failing that Barts advice sounds acceptable. 

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If these are anything like the EDs and they still run a dizzy, they fuck out fairly commonly and are in the most retarded spot

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Do an ohms resistance test on leads and see if fails first?

Or lazy mans test as follows:

While it' dark outside have it running and lift bonnet.. if u can see blue sparks jumping from leads is a pretty sure sign.. sounds silly but often will see this before a lead shows serious misfiring.. 

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Yea do ohms teat on leads google should tell you what resistance is acceptable easy to tell if ones stuffed.

I am pretty sure @igor had this issue a while back not an AU but maybe similar or same motor?

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Yep, my EA was running like a bag of shit a long time back. Thought it was fuel problems so gave it a dose of the injector cleaner recommended by 8ball to no avail then found the spark plug gaps were enormous, something like 1.75mm. Re-gapped all the plugs to 1mm and it ran sweet. Some months later it started running on five cylinders and the problem turned out to be a dodgy lead. As ky says the dizzy on these is in the most retarded place. What dumb-arse designs an engine with the dizzy so far up under the inlet manifold as to be unreachable by a normal human? My mechanic tells me that it is possible to change the dizzy without removing the manifold but you need to have smallish hands that bend the wrong way.

Short answer check the leads next cos mine looked okay but one of them wasn't.

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If your plug gap is 1.75mm, it’s time for new plugs, not a gaping. 

Checking resistance of leads won’t  always show an issue if the lead is tracking down. Those falcons run the leads from one side of the engine to the other, through the intake manifold, so lots of places for the leads to earth down and spark to escape. 

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No dizzy on the au so they put they coil pack under the manifold instead ... 

sounds like fuel problem if it comes right and runs clean after a drive coil /lead problems usually get worse when hot ... I vote for random fuel supply / intermittent earth problem 

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2 hours ago, AllTorque said:

If your plug gap is 1.75mm, it’s time for new plugs, not a gaping. 

Checking resistance of leads won’t  always show an issue if the lead is tracking down. Those falcons run the leads from one side of the engine to the other, through the intake manifold, so lots of places for the leads to earth down and spark to escape. 

Got six new plugs the second time along with the one new lead. I'm too tight / broke most of the time to replace stuff that I can rangi up and get a few more months out of. Old plugs still looked okay / good colour etc apart from the gap being huge.

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