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Wiring up Wolf V500 to VR and Distributor for sequential ignition


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I'm trying to figure out how wire my Ford VR sensor and ZXT distributor to Wolf to allow sequential ignition firing. Below is my first guess based off KTM's guide in this forum...but his is using only the distributor for the reference signal. Did I guess right?

 

Thanks in advance for your help.

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Edited by rossman
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You're on the right track. A couple things...

 

1) The red wire supplied by Wolf in the trigger harness is 5v. You can use it if you like, but 12v will provide a bit more buffer for noise. I've done both successfully.

 

2) I'm not versed with the Ford VR, so I'm uncertain of it's polarity. You may or may not have to reverse those two wires (A28 and A29). It won't harm anything to get it wrong, and the laptop will show you straight away if it's working correctly or not.

 

One question; How are you planning to use the Datsun CAS for a single sync pulse? Custom disc, or covering 5 holes, or?

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1) The red wire supplied by Wolf in the trigger harness is 5v. You can use it if you like, but 12v will provide a bit more buffer for noise. I've done both successfully.

+12v is the plan.

 

2) I'm not versed with the Ford VR, so I'm uncertain of it's polarity. You may or may not have to reverse those two wires (A28 and A29). It won't harm anything to get it wrong, and the laptop will show you straight away if it's working correctly or not.

I'll research the VR sensor to determine its polarity.

 

One question; How are you planning to use the Datsun CAS for a single sync pulse? Custom disc, or covering 5 holes, or?

I assumed (without actually looking at the software) that it could be set up similar to your "Sequencing Batch Fired Coils" sticky: "Ignition 1 Pulse Offset" is set up to fire relative to slot "0" and "Ignition 1 Pulse Skip" = 5. Every time slot 0 comes around Wolf would know cylinder 1 is on compression TDC. Can Wolf determine the sync pulse in this manner?

Edited by rossman
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I assumed (without actually looking at the software) that it could be set up similar to your "Sequencing Batch Fired Coils" sticky: "Ignition 1 Pulse Offset" is set up to fire relative to slot "0" and "Ignition 1 Pulse Skip" = 5. Every time slot 0 comes around Wolf would know cylinder 1 is on compression TDC. Can Wolf determine the sync pulse in this manner?

 

 

Not exactly. I think we need to back up a bit... your crank sensor is going to provide engine position information. All ignition and injection events will be timed to the crank trigger. The crankshaft makes 2 complete rotations (720 degrees) for the four complete cycles. The only thing the 'cam' sensor is doing is keeping track of which 'cycle' the engine is on by telling the ECU every time the crank has made two revolutions. Of course that's simplified, but the point is, the cam sensor should only be reporting one pulse every OTHER revolution of the crankshaft. No events are directly triggerd from the cam sensor in this type of installation.

 

Side note: A proper cam trigger can be used in lieu of a crank signal. Using both adds complexity and the gains are typically less than the variations normally found within A dyno. For most of us mortals, a cam trigger is more than satisfactory.

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Yeah, I'm pretty sure I understand the relationship between the crank and cam although it may not be apparent in my post. I was thinking (probably incorrectly) that Wolf could use the two closely spaced slots (0 and drilled hole, you call them "dual pulse" in the sticky) as an indicator of the crank cycle. The coil firing would be triggered by the crank sensor and the optical sensor in the distributor would be used to indicate the crank position relative to the engine cycle. Not sure how to state that in Wolf terms.

 

As an alternative, I could take your suggestion and cover all but one slot on the disk. A bonded-on thin sheet of stainless sheet might work nicely. By "thin" I mean something like this .003" thick shim material: http://www.mcmaster.com/#shim-stock/=agrfwb.

 

Cheers,

Ross

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I was thinking (probably incorrectly) that Wolf could use the two closely spaced slots (0 and drilled hole, you call them "dual pulse" in the sticky) as an indicator of the crank cycle.

 

That only applies to whichever trigger you are relying on for timing events. Crank sensor in your case.

 

 

The coil firing would be triggered by the crank sensor and the optical sensor in the distributor would be used to indicate the crank position relative to the engine cycle. Not sure how to state that in Wolf terms.

 

Wolf phraseology would be "Reference+Sync". Reference being the crank sensor and sync being the cam sensor. Again, this applies to your particular situation. If you think about it, using the example you listed above (in the sticky), the 6 evenly spaced slots would be "reference" and the additional, closely spaced slot, would be the "sync" pulse (only happens once per 720 degrees, correct?). The difference is that you're splitting the duties between two sensors. Make sense?

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I guess I am at a loss why are you trying to use two sensors to achieve what just one will do. If you drill the sync hole in the CAS you will be able to run full sequential spark without the need of the VR sensor. Ron's done it numerous times, I've done it (Ron taught me), Hughdogz did it, and I did it for Markham. If you are still using the distributor, then you do not need the separate crank sensor.

 

Ron is explaining it in Wolf terms with "Reference" and "Sync".

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...a crank trigger is a more accurate than a distributor since it shortcuts the slop in the distributor's mechanism.

 

With a traditional distributor, yes, there can be a fair bit of slop. With a turbo ZX distributor, the only slop is between the crankshaft and spur gear. I'll bet the slop is less than you think.

 

A few yeas back, I ran a test with a standard distributor. I posted this shortly after...

 

I installed a VR sensor on the crank of my 510 (still L- powered). I also installed the matchbox style elec. dizzy. This sensor is also VR. I then took a two channel O-scope and data logged both VR's. Keep in mind that the dizzy still had mech. advance (also vacuum adv. but disconnected). In general, 80% of the time, they 'scattered' inside of 4 deg.

 

That's WITH the advance mechanisms in place, and that is where the brunt of the slop is going to be found, by far.

 

I bet if KTM puts a timing light on his car, the crank damper will appear to be rock solid, or pretty close, as long as there isn't excessive wear on those two parts.

 

Don't let us dissuade you. If two sensors makes you happy, go for it. Just trying to make sure you get what you want.

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Ross, I am with you on pursuing the most accurate timing method possible. I have spent some time around an engine dyno and I can tell you that one a degree error in ignition timing on a high compression (16:1+CR)engine is critical,

big horspower gain/loss or melted pistons.I would also mention that most OEMs have used both a cam and crank sensor (even in the absence of variable cam timing).

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Ross, I am with you on pursuing the most accurate timing method possible. I have spent some time around an engine dyno and I can tell you that one a degree error in ignition timing on a high compression (16:1+CR)engine is critical,

big horspower gain/loss or melted pistons.

 

 

And none of them were mild street cars relying on pump gas.

 

Please keep some perspective on what Ross is building. It's not an F1 qualifier, Top Fuel, or NASCAR. It's a mild motor, running mild boost, on inconsistent fuel. For his goals, a +/- shift of 2 degrees from MBT won't be consistently measurable with common dynamometers. Been there, done that. Further, if you are attempting to run that close to the ragged edge on a street car, I would probably recommend getting some counseling for that gambling addiction you're fostering :wink:

 

I would also mention that most OEMs have used both a cam and crank sensor (even in the absence of variable cam timing).

 

Yes, modern OE engine management REQUIRES them. Not for the purposes of power or melted pistons. They're there to meet the stringent regulations of OBD (miss-fire tracking is the big one). Not only is this complexity not necessary for most of us on this forum, none of the mid-range EMS's have the ability to take advantage of that technology. It's moot in Ross's case.

 

Additionally, all things being equal, two position sensors have twice the potential for failure. Lose either one while visiting Aunt Nelly in Nebraska and you're parked until diagnosed and repaired. Lose a cam sensor on a modern OE car, and you'll still limp home. Different technology for different purposes. Apples and pears.

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No worries. There are other reasons why I chose to simplify that I didn't state in the thread. The crank sensor mount sticks out and interferes with stock fan, requiring the fan to be offset to clear it. Offsetting the fan forward places it too close to the radiator for comfort. Now I don't have to worry about any of those issues.

Edited by rossman
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Ron,

Good point, that a single point failure is going to leave you stranded with this type of stand alone aftermarket F\I.

As where the OE will allow limp home function.

 

I agree that the distributor trigger is sufficient in this case, I guess I got sidetracked making the point that there is some merit to having a crank trigger.

Respectfully ,Pete

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