Tell me about coil on plug

[KidVermicious]

3RZ motor, if it matters. Remember that I've learned my wrenching on carbed motors and early EFI trucks with distributors, so talk slow and use small words please .

The 3RZ going into the Bastard is from a '96 Tacoma. It has a distributor. I've hit a roadblock trying to get a timing signal into the aftermarket computer I've decided to use, so I'm looking for options and would like to know if a conversion to coil on plug is something I should consider.

So some questions - on COP motors, does a cam position sensor replace the distributor? Does it bolt into the same position on the block, or would I need to open a port for it? How does the CPS work specifically - is it a reluctor, or a hall sensor, or optical or what? Does it work off the same cam I have on my early 3RZ, or would I need to change cams or add a trigger wheel or anything? What else don't I know about COP that might be relevant?

 

[IBallEngineer]

At the risk of not addressing your issue, may I ask why you can't get a timing signal to the computer?

 

[KidVermicious]

The 3RZ distributor reluctor has one tooth. The Megasquirt wants to see two pulses per crank revolution, which would require four teeth. I will probably end up putting a trigger wheel and Hall sensor on the crank pulley, but if switching to COP is easier and would solve the problem, I might do that instead.

 

[TheDurk]

I'm not familiar with the 3RZ but I do have a paper FSM that covers it. It appears that 3RZ-FE is not actually a COP. There are two twin coils that are connected to the plugs by high-tension plug wires just like a dizzy.

The coils are fired by an igniter that is triggered by the ECM. The ECM uses both a Camshaft position sensor and a crankshaft position sensor. The cam sensor uses a signal plate with one magnetic tooth and a pickup coil through a port on the driver's side of the engine.

The crank sensor plate is mounted on the crankshaft (duh), has 34 teeth and there is a pickup sensor with a port on the lower driver's side behind the alternator.

Hope this helps. It certainly doesn't sound any easier. Your ECM is not going to like you for running a dizzy, though. A permanent CEL is in your future, I suspect.

 

[KidVermicious]

Thanks Durk, that does help.

The Megasquirt likes distributors in general just fine, it appears to be this 3RZ distributor in particular it has an issue with. I don't know how the stock Toyota computer likes this distributor, to be honest... there's only one gap in the crank sensor teeth, and only one tooth on the reluctor in the dizzy, and no other crank or cam position sensor. I'm forced to conclude the early 3RZ estimates where the other three cylinders are in their cycle, and that seems bonkers.

Hall sensor/trigger wheel, here I come.

 

[IBallEngineer]

Thanks Durk, that does help.

The Megasquirt likes distributors in general just fine, it appears to be this 3RZ distributor in particular it has an issue with. I don't know how the stock Toyota computer likes this distributor, to be honest... there's only one gap in the crank sensor teeth, and only one tooth on the reluctor in the dizzy, and no other crank or cam position sensor. I'm forced to conclude the early 3RZ estimates where the other three cylinders are in their cycle, and that seems bonkers.

Hall sensor/trigger wheel, here I come.

That is funny.

I have a 2000 3RZ, if you would like any real world test performed, just ask. Between my ADD, OCD and the burgeoning turrets, I can do it!

:argue:

 

[davidch]

3Rz ignition systems

I believe three different ignition systems were used on the 3RZ.

1) a distributor
2) a pair of twin lead coils (my 2000 4Runner with the 3RZ has this)
3) coil-on-plug (my 2002 Tacoma, with the 2RZ, has this; I assume that in 2001 or 2002, the 3RZ, now only in Tacomas, made a similar conversion to COP)

 

[Mc1337sauce]

I believe three different ignition systems were used on the 3RZ.

1) a distributor
2) a pair of twin lead coils (my 2000 4Runner with the 3RZ has this)
3) coil-on-plug (my 2002 Tacoma, with the 2RZ, has this; I assume that in 2001 or 2002, the 3RZ, now only in Tacomas, made a similar conversion to COP)

This is correct; my dad's old '95 T-100 had the 3RZ with the distributor, and my '97 4Runner has the twin coils.

I don't have any experience with the COP version of the 3RZ, but I know there was a thread on CustomTacos about converting from a distributor setup to COP, which may be of use to you if you want to investigate that option further.

 

[TheDurk]

Thanks Durk, that does help.

The Megasquirt likes distributors in general just fine, it appears to be this 3RZ distributor in particular it has an issue with. I don't know how the stock Toyota computer likes this distributor, to be honest... there's only one gap in the crank sensor teeth, and only one tooth on the reluctor in the dizzy, and no other crank or cam position sensor. I'm forced to conclude the early 3RZ estimates where the other three cylinders are in their cycle, and that seems bonkers.

Hall sensor/trigger wheel, here I come.

OOPS. I didn't realize it was going INTO an '85. Yeah, good choice, you'd need an ECM, igniter, the twin coils, and cam and crank wheels and pickups and it would be a complicated beyotch to pull off.

As to the other three cylinders bonkers thing, mechanical dizzies worked fine (mostly, tune-ups with contact points were a drag) for the first 75 years of automotive history by just timing #1, believe it or not.