No 6 plug wire "pulse generator"

#1

I just bought a new set of plug wires that does not include this wire. How does one move the sensor from the old wire to the new? Does it matter. Does anyone transplant the rubber dust covers? This the strangest ignition swapover I’ve ever done.

#2

Take them back and get the right set of wires.

#3

Right set can be identified by an integrated pulse generator on wire 6? I buy stuff in batches and install it in a distributed fashion, may have passed the warranty return period. Any proven mods to use the wrong wire set with the existing sensor?

#4

Someone told me recently that their M20B25 ran fine w/o the inductive pickup on #6. I recall expressing surprise that this worked. I don’t recall who it was. They might have been full of shit.

Buy an inductive pickup wire from the right honorable Rev. Al Taylor. See if you can’t thread it on to the plug wire w/o cutting the wire. I don’t think that cutting the #6 wire will work well…you’d end up adding impedance and #6 might not fire as strong as the others.

Or just get a couple sets of plug wires from the pickNpull. Pull apart the plastic casing and take #6 wire.

#5

I’ve read a few threads where folks claimed no discernible difference with the No. 6 wire sensor missing. On a megasquirt forum the explanation was that the sensor times the sequence for a semi-sequential firing of the fuel injectors. Economy and emissions might suffer a little but probably not a big deal for overall performance. Sounds plausible. Maybe I’ll just reuse the no. 6 wire.

#6

I run a set of msd 8mm wires, it was one of the first things I changed on the car 8+ years ago before I knew any better. The msd wires didn’t come with the pulse generator so I just simply pulled it off the old wires, removed the boot off one of the wires and installed it onto the new wires. I think I actually installed it onto the no.1 wire. It has never caused a problem.

#7

[quote=“Ranger” post=72227]
Take them back and get the right set of wires.[/quote]

Should have done this. Along with sticking to Bosch. This has been a nightmare. Although I paid a mint for them and the construction looks good, between new wires, cap and rotor (none of which was cheap) the car either barely runs or doesn’t run at all after several hours of screwing with stuff. I can hear the ignition arcing and misfiring in or near the rotor cap. About to send a stack o’ Benjamins to Turner.

#8

I’m actually interested in this. I don’t believe I have any sort of extra on my #6 wiring, but will be checking tonight. Someone referred to it as an inductive pickup? My understanding is that an inductive pickup is to read the signal. The only reason I can think of using that is for the ECU to somehow send a counter signal based on the pickup signal to counter any EMI?

#9

It won’t be to counter EMI for many reasons. The MS forum explanation makes sense if the fuel injectors are batch fired in some bank related order. In other words the ECU tells a bank of 2 or 3 fuel injectors to fire together near the times when their cylinders’ intakes are going to open. If you squirt fuel onto a closed intake valve and it just sits there for a while as opposed to near when the valve is going to open, it probably doesn’t make a lot of difference in the amount of power that the engine eventually makes but it may influence emissions. So the inductive pickup is a signal to the ECU that cylinder 6 has just started a combustion stroke so that it can get the bank timing correct. As reported the ECU apparently can get along without it.

#10

It makes me think the car doesn’t know when cyl 1 is going to fire based on the crank trigger. Do these cars have a cam position sensor? I don’t remember ever seeing one. Then again, I have only taken the valve cover off twice.

#11

IIRC the M20 doesn’t have a cam sensor since the cam is fixed. The crank trigger doesn’t tell you which stroke you’re on. Hence the #6 cylinder sensor. All supposition on my part.

#12

Your an EE. You can Macgyver it.

#13

That is exactly right.

#14

The harmonic balancer is missing a tooth. I think that allows the crank pos sensor to tell the DME when #1 is at TDC. The cam turns 1/2 as fast as the crank so 1/2 of the crank tdc’s the cam is at tdc and the other half of crank tdc’s the cam is at bdc. The #6 sensor is the means to tell the DME if cam is at tdc or bdc. At least that’s my theory.

Re. injectors spraying in 2 banks instead of 6 individual timed pulses. I’ve never really understood how this could be an optimum way to spray fuel in. Who the hell would come up with such a goofy idea? Imagine a table of Bosch engineers talking about engine management for a 6cyl in 1978. One guy says “Our testing shows that the optimum time to fire each injector is 30deg before tdc at the end of the intake cycle.” Then the meeting’s smart-ass says “Lets try something oddball just to see if the engine can still run”. The engineers laugh and then called up the software guys and directed that design change. Then the 4 Bosch engineers crammed themselves into their 2002 and attempted to reconvene at the local Brauhaus. Tragically, their 2002 was squashed flat by an American Army truck out on maneuvers and the banked injector jape was never corrected.

#15

Excellent theory but probably wrong :slight_smile: Bank fired injectors have been around a long time. But you do pique my interest as to who came up with the notion. I’ll speculate that the compute power in early ECU’s was so limited that the new FI guys, who were EE’s, said to the old FI guys, who were MEs, “Look, sorry about this but we can’t give you optimum injection times, can we just do it all at once?” The MEs were naturally agog that the EEs, with their new fangled arcane technologies, could make such a stupid and obviously backward suggestion, but the oldest FI guy, who had been rebuilding SUs and Strombergs for half of his life said, “Well, it seems to more or less work for carbs, why not?” And the accountants rejoiced because the new FI system controllers cost about half of their older mechanical counterparts. Hence batch/bank fire and throttle body injection were born. And they all went down to the Brauhaus and just had time for a nice Duvel before the tanks arrived.

#16

[quote=“turbo329is” post=72310]Your an EE. You can Macgyver it.[/quote] LOL! It runs like I already tried! Plus the full MacGyver treatment is illegal and a lot easier to detect than your octane switch trick.

#17

I am highly doubting the M20 uses bank fired injectors, and to be honest, I’ve never heard of that (and I’ve been in combustion for a while). At that point it would be WAY more efficient to use a throttle body injector style setup.

Either way, I’m still curious why the car needs the #6 pickup. Is it for the DME to set a fault code for OBD1? That would make sense if it was related to a misfire.

#18

[quote=“Foglght” post=72320]I am highly doubting the M20 uses bank fired injectors, and to be honest, I’ve never heard of that (and I’ve been in combustion for a while). At that point it would be WAY more efficient to use a throttle body injector style setup.

Either way, I’m still curious why the car needs the #6 pickup. Is it for the DME to set a fault code for OBD1? That would make sense if it was related to a misfire.[/quote]
The engine definitely fires the injectors by banks. Bank 1 is cylinders 1, 3, 5 and Bank 2 is cylinders 2, 4, 6. The Cylinder ID sensor on the #6 plug wire is used to time the bank firing. If that signal isn’t present the DME switches to firing both banks at the same time.

Bank firing is a reasonable compromise between the ideal (timed sequential firing) and the complexity & cost of the the DME.

#19

You need to get out more Ryan. Check out Ford’s EEC-IV.