December 13, 2010 05:16PM
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Registered: 15 years ago
Posts: 1,869 : Amagansett, New York |
Hi Guys
On one of the plug wires there is a smaller wire that leads off in to the timing cover and hooks to a snap block on the left side of the motor by (over) the alternator. There are two plugs on the plate together and I think that wire (from one of the plug wire) goes on the inner block but I'm not sure. Anybody know? and what does that wire really do ..... will I get better mileage, will it grow hair?? Thanks, Rick |
December 13, 2010 07:21PM
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Registered: 15 years ago
Posts: 1,538 |
That is the inductive pick up for the #1 plug. It goes back to the Motronic unit and the signal is used to aid in firing the injector banks. If it is not connected, it doesn't seem to affect the operation of the engine at all. Whether it will affect fuel consumption is anybodies guess. You could leave it unhooked for a couple of tanks of gas and keep track of your mileage; then hook it back up and repeat. Then compare the figures and see if it makes any difference. |
December 13, 2010 07:42PM
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Registered: 15 years ago
Posts: 1,869 : Amagansett, New York |
Thanks Peter, so,if it's disconnected the injectors fire twice as many times as usual? |
December 13, 2010 09:51PM
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Registered: 15 years ago
Posts: 636 |
Rick, that has been my understanding. It has the potential (dependingon engine position) to shorten the crank time. I've never heard a better explanation...I've never heard a different explanation, come to think of it ----------------------------------------------------------------------------------- 1989 - E30 - M20 - Manual. Approximately 270,000 miles 2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles Edited 1 time(s). Last edit at 12/13/2010 09:53PM by Earendil. |
December 13, 2010 11:35PM
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Registered: 15 years ago
Posts: 609 : SoCal |
December 13, 2010 11:59PM
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Registered: 15 years ago
Posts: 636 |
It shows up on my 89 6 cylinder. However it should be noted that because these cars do not require it, the majority of people don't know what it does, and some replacement plug sets don't even have it, that many cars that originally came with it no longer have it under the hood. Due to the location that it plugs in, you'd have to get very intimate with your car, and be paying attention, to notice anything was amiss. ----------------------------------------------------------------------------------- 1989 - E30 - M20 - Manual. Approximately 270,000 miles 2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles |
December 14, 2010 09:22AM
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Registered: 15 years ago
Posts: 609 : SoCal |
December 14, 2010 10:25AM
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Registered: 15 years ago
Posts: 188 : Sunny South Africa |
The one on my '91 318i (M40) has been broken off since I got the car, and and in all the years I have had it, I have never had any running problems, I consistantly get 13km/litre or 7.6 litres per 100km, which seems right about the book figure, so, no I doubt it has any adverse effect on fuel consumption.
---------------------------------------------------------------------------------------------------------------------------------- E30'S AREN'T BUILT, THEY'RE CAUGHT IN THE WILD!!! When in doubt, use full throttle, it may not improve the situation, but it will end the suspence. |
December 14, 2010 03:08PM
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Registered: 15 years ago
Posts: 1,869 : Amagansett, New York |
From 1987, 325i's, in the USA, had this extra lead wire from the plug wire. The four bangers (later models, not M10's) I don't know about, but from what I've heard here, this wire might save a fraction on MPG but it times the injector bank firings. So. if it's disconnected (I'm pretty sure) the injectors fire twice as much as they would if it was connected. I'm pretty sure I remember a few other minor plus' you get if it's hooked up. In my case I'm going to route the wire (temporarily, until I do a timing belt) over the top of the valve cover in front and tie in to the block under the thermostat housing, the wire should reach. The Eta's don't have this set-up at all. Rick |
December 14, 2010 05:09PM
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Registered: 15 years ago
Posts: 1,538 |
If the wire is missing, the ECU doesn't fire the injectors twice as often, it just fires the banks from a default. That means that the bank that has #1 plug and # 1,3 and 5 injectors would fire at the optimum time. But since only one of those cylinders is on the intake stroke at a time, The fuel charge on the other two simply sits in the intake plenum until the intake valve opens and sucks it in. Since only one of the six cylinders is on the intake stroke at a given time, it really little difference which bank of injectors fires when. The same amount of fuel will be available to each cylinder; just that the charge may not be as freshly atomised as it could be. |
December 14, 2010 06:00PM
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Registered: 15 years ago
Posts: 609 : SoCal |
December 14, 2010 09:09PM
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Registered: 15 years ago
Posts: 1,869 : Amagansett, New York |
So, we're talking about fuel injector pulse timing, as in degrees, yes? It's weird, I'm a car guy and I'm having trouble seeing this in my head Peter. |
December 15, 2010 10:37AM
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Registered: 15 years ago
Posts: 670 |
December 15, 2010 02:33PM
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Registered: 15 years ago
Posts: 1,869 : Amagansett, New York |
Thanks Michiel, I understand. Today I got decent time in on the car, there was plenty of wire to run over the top of the motor and through the water hoses down to the mounting plate, that firing wire plugs in to the inside hole in the metal holder plate. I cleaned all the connections and got everything together (well, I'm still at it actually) and will finish tonight. While the car is in here I have a few other things on my list, my goal is to, someday, fix my damp weather starting issues |