355 Cam phase sensor malfunction

Sorry if you never said CEL. I presumed the code was accompanied by a cel. A cam sensor error should throw a cel. Maybe it was a "pending" error?

Agreed that it would be a strange coincidence, but say that side was running rich and carbon was building up on all the plugs. You might not notice a minor misfire and then all of a sudden two plugs, almost simultaneously, foul on the different branches of the coil. It could happen. Seriously, we are looking for something out of the ordinary here.

Nah, I've had the plug coves off my car a 1/2 dozen times. Haven't replaced the gaskets yet. They have come off undamaged. Besides, they don't do a dam thing other than cushion the cover unless you drive in the rain or spray the engine down when washing it.


As for your second post, big bang? I doubt it. You said you pulled the bad bank's injector fuse or relay, so there shouldn't be anything to go bang. But if you not comfortable doing it, don't. Mrio has a good suggestion about the series resistor, but I measure the DC resistance of the primary as 1.7 to 1.8 ohms between pins 1 and 3. So that mean 0.8 ohms or greater for each side. That would limit the current to 15 amps max. If you want to limit the current to 10 amps, a 0.4 ohm resistor would be in order.

I have an old coil I could bench test if I can find a couple of old plug leeds.

 

Well, I bench tested this with a 355 coil, no resistor and no cap. I was able to get a consistent spark by just swiping the ground wire against the battery ground. The shorter the contact the hotter the spark. The bad news was that it was not sufficient to flash my spark tester.

You could pull the plugs and ground them to the block and then test and observe for spark. The problem with that is that it would not be an in situ test and wouldn't verify anything.

 

When I measured with a Fluke multimeter which auto compensates for the resistances of its probe wires and connections, I got 1 ohm Pin 1-3 so each primary coil has 0.5 Ohms. It is not easy to measure such low resistances with a standard multimeter. Before measuring the resistance, you need to connect the probes to each other tightly and record the residual resistance (usually around 0.5 Ohm) then deduct this from the actual resistance reading. When taking the actual reading, you also have to press the probes rather tight onto the pins, rotate them a bit to rub-in and see what the lowest Ohm reading you can get is

 

With wasted spark ignition, you don't need to ground the spark plugs as the coil secondary is not grounded. Just identify which two plugs are on the same secondary winding by checking resistance on the coil secondary connectors and establishing the pairs. Then connect two plugs to each identified pair and tie the plug bodies together. You can then watch how the two plugs are sparking simultaneously.

 

To clarify, the "grounding" was to complete a loop around the secondary in a similar manner as occurs in the engine where the loop is completed through the engine block (ground). But as I stated removing the plugs to performing this test won't provide an answer to the question of, " is the secondary side ok" as if you removed the plugs from the engine the secondary wiring will be disturbed and the change could effect the outcome. It needs to be tested in situ. But if a spark detector won't fire when laid against a plug wire when the plug is firing then test may not useful. However, if it fires, you know the secondary is good, and the problem in on the primary side. If it doesn't fire you haven't learned anything.

As for the coil impedance. My measurement was correct. It may be high because it was an old coil that I removed from the car because of an ignition problem. One side was dead on the secondary side. The primary may have been on the way out as well, resulting in higher impedance than normal.

 

In the case of wasted spark ignition, the loop is actually completed through the cylinder head only with the HT travelling from one to the other spark plug of the pair connected to one secondary coil. The ground of the car or engine (battery negative) does not play any role in the HT sparking across the plug electrodes. The HT travels from one side of the secondary coil to the centre electrode of one plug, jumps to the "nose" of the plug, travels through the body of the plug, through the cylinder head, finds the other plug, jumps from the "nose" of the second plug to the centre electrode and goes back to the ignition coil, i.e. to the other side of the secondary coil - loop closed. One of the spark plugs of the pair always sparks in the "wrong" direction (nose to centre) but it does not matter for the ignition of the mixture.

 

BS. Ground it ground. The cylinder head is ground. So what's the potential difference between the two plugs? What is the potential level of the cylinder head?
If the potential level is greater or less than the ground potential, current will flow to or from the battery. For all practical purposes the potential difference between the plugs through the head is zero because the resistance between the plugs through the head is negligible. If there is any significant difference between the plugs then at some point in the head the potential must be greater than the ground potential at the battery and current must flow to the battery. You really need to think about the system before you comment on how a part of the system behaves.

 

John, so you're saying that with both plugs in a pair removed, you still get a spark? I wouldn't expect to get current flow in a standard electrical circuit, either, when one end of a wire is not hooked up to anything. I'm not saying that this is a standard "light switch" circuit however. Like a battery, the coil has potential energy, but you still need two wires hooked up to a battery to make current flow.

By the way, I've given wrong answers on the forum, all too frequently, but I usually get a polite correction. I don't expect someone to call "BS". Having said that we understand your frustration on this topic. We are all having difficulties understanding Grant's problem.

 

You are not considering one important thing in the case of wasted spark ignition: none of the secondary coil sides is grounded (unlike the standard ignition coils). The wasted spark secondary coil is "stand alone". One side of the secondary coil is connected to the centre electrode of one plug and the other side of the coil to the centre electrode of the other plug. The HT potential difference is across the gaps of the two plugs with the cylinder had being just a conduit for the HT from the metal body of one plug to the metal body of the other plug. You could have the whole engine made of plastic and, if you have a wire connected between the bodies of the two plugs, they will spark. The primary side of the ignition coil, however, needs the ground (the negative side of the battery) for the circuit to be closed as the positive side of the battery is connected to one side of the primary coil.

Perhaps this illustration will help understand the wasted spark HT flow better, including where the potential differences are.

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It's always best to double check. That cam wire may be shorting to ground instead of going to the computer (perhaps when it's subject to vibration). Have you tried running the engine with the cam sensor disconnected? Perhaps no signal is better than a corrupt signal.

I had another look at the my diagram and all the other diagrams I have available just to make sure I had that cam sensor hooked up to the correct pin. Pin 21 is definitely the cam sensor. If you have time, though, could you check the colour of the wire at pin 46 (middle row). It's not related to the problem, it's just that I have two diagrams disagreeing with each other. In one diagram, it shows as black (an earth wire). In another diagram, it shows as purple-black.

Thanks.

 

Here's another illustration:

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Grant, when you were checking the signal at the cam sensor, were you checking it with the cam sensor plugged in?

 

One unlikely but simple possibility: did you, for some reason, disconnect and reconnect the HT leads for the "dead" bank from its ignition coil before you encountered the problem?

If the HT leads are accidentally connected wrongly to the coil, the bank will not fire. In any case, when you remove the plugs and test for spark, you will know whether the problem is due to absence of sparks or due to something else.

Another thing you mentioned early in the thread is "the banks sounds as if it is pumping air". This could happen if the timing belt for that bank skips. Is there a relatively easy way, on the 355, to check the cam timing on the offending bank?

 

Miro, you are not paying attention. NO SPARK. How the hell is connecting the plugs in the wrong order going to cause no spark. Wake up man! You are cluttering this discussion with garbage.

 

Why don't we stop copying illustrations from the internet that don't properly represent the system just to make your point. Let's present a better representation.

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The plugs are connected to ground.

Now, even that is not entirely true. The head, or any other part of the car is not a superconductor so a better representation would look something like this:

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And this is still an over simplification. R1 is the resistance of the head between the two plugs, R2 the resistance of the head between the socket for one plug and the engine ground strap, R3 the resistance between the second plug and the ground strap, R4 the resistance of the ground strap and any other resistance elements between it and the battery. For any current to flow between the plugs V1 must be greater than V2. Even if R4 were zero so that V3 = Vg, since V1 > V2, one or both of V1 and V2 can not be equal to Vg. Thus, physics dictate that there is some current through either R2, R3 or both.


Now, you can wave your hands as much as you like that these resistances are small and that the differences between V1, V2, V3 and Vg are small and negligible. But the head is grounded and regardless of what the current path is, the plugs are in connected through the head and grounded, so suffice it to say, the loop is completed by connecting the plugs to ground, and the first figure I posted is sufficient to describe the connections.

Just because a component is connected to ground doesn't mean there is a current flow from that component to ground. Consider a double ended power supply, +12V and -12V. Connect a 1k resistor between +V and G and another 1k resistor between -V and G. The current flows between +V and - V with zero current to ground. But loop is completed by connecting both resistors to ground. Get it?

 

A simple pen type. (Sorry for all the BS but Miro is stating to piss me off with his nonsense that is completely irrelevant to your problem. )

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Oh, and re pumping air, that's what an engine is. Nothing more than an air pump. Without ignition that becomes apparent. Suck it in the intake, blow it out the exhaust. Forget mister brilliant's comment about a belt skipping a tooth. More nonsense, unrelated to your problem. But you better check the pressure in your tires because low air pressure is know to result in no spark on one bank. I'm sure I read that somewhere.

And again, sorry to detract from your thread, but I haven't had this much fun in years.

 

The resistances you showed are probably in the order of 0.01 Ohm or less which, in the case of HT (some 50,000 Volts), mean nothing. Otherwise, the HT coming out of the secondary coil is not attracted to the ground since none of the secondary coil ends is grounded. The HT discharge loop goes from the centre electrode of one plug to the centre electrode of the other plug, after the HT has jumped over the gaps of both plugs. That is why the spark jumps centre to nose on one plug and nose to centre on the other plug. Very simple. There are some good articles on the internet about the Wasted Spark Ignition.

 

Make sense to me. Electricity takes the path of least resistance. A missing engine earth wire, or even a missing lower half of the engine is not going to interrupt the secondary coil circuit. However, a single faulty spark plug lead will affect it. But that doesn't explain why four sparks are missing.

We have had comments on "finite resistance", but not so many on what would cause this finite resitance or why it should affect 4 cylinders. If it wasn't raining at the time of the failure, what else could be finding its way into all the spark plug cavities without it being visible from the outside? Oil. And how does this finite resistance affect the cam sensor signal.

I think Bosch is hiding something from us Grant, does your oil smell of electrons?

 

Failure of one plug or one HT lead will cause no spark on two cylinders of the bank, on the one where the fault is and on its "mate". If two plugs or two HT leads on one bank fail, and if they happen to be on different secondary coils of the ignition coil for that bank, all four cylinders of the bank will have no spark.

 

So, the plugs are screwed into the head. Is the head grounded or not? Yes or no? Yes, the heads are grounded. QED, the plugs are connected to ground when installed in the engine. The loop is completed through grounding. When you bench test the circuit and simply connect the plugs together it is not. What the potential difference between the head and negative lead is in the left figure and what it is in the right figure. Hint, in the right figure it's zero, neglecting any parasitic resistances. Will both configuration generate spark? Yes. But they are not the same. Which one represent what is in the car? And notice, both these figure are dealing with discharge current, after the spark has formed, not with the formation of the spark which, remember, is the issue, or , i.e. lack there of.

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