60-2 Trigger

[66wedge]

I've got a 2.0L turbo Mitsubishi with a 6-bolt 4G63 fitted with a 60-2 Electromotive crank wheel (roughly 6.25 inches in diameter). I have it set up for sequential/traditional fueling so I'm still utilizing the cam sensor portion of the factory CAS. Idle, part-throttle, and full throttle are all good, the problem; I can't go beyond 5100+ rpm. The tach needle just buries itself as it loses signal. I've tried all manner of filtering and calibrating Trig 1 and Trig 2.  My crank gap doesn't occur anywhere near the sync tooth on the cam sensor, and I have all safety limits set to off etc. And I've even tried mag sensors and hall-effect sensors, I'm currently using a Cherry brand hall effect for the crank. Would a 24 or 36 tooth wheel be a better fit for a four cylinder of this style or go to a physically larger diameter 60-2 wheel with larger teeth? Thanks for any help!

 

[Adamw]

What ecu?

A 36-1or2 is generally less fussy but 60-2 is still very common so it should work.  The diameter doesnt really matter, just the tooth size has to be compatible with the pole size (relucter sensor) or bias magnet size (hall sensor).  If you can post a photo I might be able to spot something. 

[66wedge]

Its a Fury. I'll snap one first thing in the morning. Thanks.

[Adamw]

Please do a couple of trigger scopes also.  Dont bother at 5000RPM, but maybe do 1 at idle and 1 at say 3000RPM.

[Brad Burnett]

What is the air gap on the crank sensor?

[66wedge]

Sorry for the delay, I had to scope it on lunch break. The scope shots and picture are lousy. The sensor gap is .034 inches and its pretty much centered.

scope3k.lnk

scope-idle.lnk

[Adamw]

What are your trigger scope files with .lnk extension?  That trigger wheel wont work with a hall sensor since the "half depth" missing tooth will sometimes be seen as one long tooth.  It should work ok with a reluctor sensor though.  I would still like to see the trigger scope to confirm.

Note when you do a trigger scope you can save them as a log file.

[66wedge]

Very well let me scope it again. When I did have their supplied mag sensor it still acted up. Let me get those shots for you. Thank you.

[66wedge]

Tried saving as a log but couldn't view it. I hope these two work.

[Adamw]

Not much wrong with those two scope pics, so I can only suspect the tooth size is a bit marginal for it to work reliably at high speed.  Im assuming you do have the pullup turned on?  

Below is what the datasheet for that sensor says about tooth size, so to me it appears your wheel might be pushing the boundaries a bit for that sensor:

 

Is it a big job for you to refit the reluctor sensor?  I would like to see a scope of that if we could - if the sensor was sold with the wheel then you would expect them to be compatible...

[66wedge]

Yup pullup is on. I can try to hook the old mag sensor back up, not a terribly big deal. The one thing I did notice and it never was obvious until snapping the picture of the sensor and wheel, is the lip of the balancer fills in the "trough" area of the teeth quite a bit. When I bought the trigger wheel, quite a while back, it was specifically for my early generation engine, but I'm assuming it was designed around the factory harmonic balancer. I'm running a Fluidampr which is a pinch larger, diameter wise.  Due you think it would be wise to get a larger wheel? Thanks for all the help Adam, you gentlemen are the best.

[Adamw]

I dont think the balancer OD is causing an issue yet.  I still think we should be able to get your reluctor sensor working ok.

[66wedge]

Adam here's an old scope shot of the mag sensor prior to swapping to the hall one.

[Adamw]

The reluctor scope above does revel a potential problem but nothing I would expect to cause you high rpm issues:

The missing teeth are very near TDC were crank decceleration is greatest.  This can make the "gap" more difficult for the ECU to see.  It is also not a great idea to have the missing teeth anywhere in the region of normal ignition timing (i.e 0-40deg) as engine position information is less accurate during the missing teeth event.  The best location for the gap on a 4 cyl engine is somewhere around either 90° ATDC or 90 BTDC.

Having said that, these factors would generally be more of a problem at low speeds so I doubt they are related to your problem.  If it its not a big job to shift your trigger wheel about 90deg it will only be better.

So I dont see any good reason why this reluctor sensor and wheel shouldnt work for you.

I initially thought our trigger scope might not be very useful at high RPM with this tooth count but I just tried a 60-2 @ 8000RPM and our trigger scope still captured it accurately so at least we have a tool you can use for diagnosis.  I suggest you go back to the reluctor, then if you still have trigger errors at high RPM then do another trigger scope at that RPM and we will see if that gives us any clues. 

[66wedge]

Very welI I will rotate it 90 degrees. Since it still has the hall sensor currently, should l try that out first before swapping back to the mag sensor? Thanks for your help Adam.

[Adamw]

You can try - although I dont think this is your problem, the same "gap location" rules do still apply to hall triggers.

[66wedge]

Okay.

[66wedge]

On a side not which is the preferred method for a trigger, reluctor or hall sensor. Thanks again for all your help Adam.