New exploration---Comments invited

C

cammerfe

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I've run into a NEW 'miss' problem. Those who frequent this forum will remember that I replaced, back several months ago, all my coils with ACCEL coils designed for the three valve 4.6 Mustang. (I'd previously replaced a couple of coils and the cam cover gaskets. When going to the ACCEL coils there was no indication of oil or water in the plug wells.) I replaced the plugs at the time I put the coils in.

I first noticed a little 'flutter' while on the highway on a 100+ mile trip. This degree of miss has continued, on an on-and-off basis since that time. At times it's fairly pronounced, and at other times it's hardly noticeable. Around here, in daily city driving, I'm getting 15-16 MPG, not markedly different than at any time previously. I now have 121 K miles on the clock.

I've concluded that I have an injector in process of failing. One reason for this opinion is that there seems to be no concomitant converter difficulty. I'd believe that putting extra gasoline into the exhaust due to intermittent ignition should result in a plethora of carbon in the cat-con.

I have the set of injectors that came out of the 4.0 AJ27 engine that I'm building. My first thought was to compare them with the 3.9 injectors. (It would be nice to compare both kinds side-by-side to see if they are 'switch-able' before tearing into the top-side of my daily-driver 3.9.) I don't have much doubt regarding similar flow, but there may be some physical difference that'd preclude this swap.

So whatta yuh think? Keeping it in mind that my purpose is simply to keep my daily driver running until I can get the 4.0 engine together and ready to put in.

Or can you think of another reason for the 'stumbly' occasions I'm now putting up with. The car still starts flawlessly and has given no signs of not getting me where I need to go---I'm just putting up with an annoyance.

Your thoughts are requested.

KS
 
Its the ACCEL coils, that is why I got rid of mine. They car misfired all the time and was worse as time went on.
 
Motorcraft coils are the ones that cause the problem in the first place. I've never had a failure with Accel coils.
KS
 
Quik--
One more time you seem to come up with the 'skinny'. I knew, of course, of the air assist. The question is whether the non-assist injector will physically fit into the opening on the manifold and seal. Or, asked another way, are the o-rings in an appropriate place, and are the diameters 'right'? In that case, it should be fairly simple to plug the air origins. The metering wouldn't be quite right, depending on where the 'extra' air is coming from, but it would, quite possibly, be less of a problem than the on-again-off-again of a failing injector.

The problem, of course, is that I have to do a tear-down to have one of each kind in hand to do a comparison. Would your experience make it possible for you to hazard a guess?

Thanks in any case!!
KS
 
well - anything is possible.

On the stock injectors - you can see that the bottom o-ring is actually an inch up from the tip - on the body, and that the inch below the o-ring pushes through the manifold. So a standard injector would not seal up right - nor would the tip protrude enought out the bottom of the manifold.

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if you could get by those issues - then you would have to cap off all the lines running into the air rail - and the feeder on the IAC.

I just tried fitting a standard EV6 into it - maybe with enough pressure down on the injector the bottom o-ring could seal - but the tip is still buried up in the manifold too much (maybe the spray would clear it...)
 
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