Original Nissan RB CAS & 60-2 Crank Sensor

I have a RB30/26 NA engine in a 260Z and has been running very well competing in sprints etc for 4 years

The car is using an Adaptronics M2000 ECU, 60-2 Crank Sensor and still has the original Nissan CAS fitted ( setup before I bought it )

Recently after several periods of sustained high rpm (Conrod Straight) the engine is running very rough.

The engine runs fine when I unplug the CAS.

I have been doing intensive diagnosis to determine if the CAS is faulty or if the Cam belt has stretched enough to upset the timing of the trigger signal.

MY MAIN QUESTION IS - before I replace CAS

I cannot read anywhere if a Standard Nissan CAS with 6 home pulses can work properly with a 60-2 Crank Sensor ?

All I can find through reading is the use of a single pulse CAS with a multi tooth Crank sensor

On the scope I can clearly see 6 pulses from the CAS and 58 from the crank

I have been wondering if my CAS may have been originally modified to only show 1 pulse and whatever covered the windows has flown off at high rpm ?

I dont want to just fit a new single pulse CAS until I understand what has gone wrong

Thoughts anyone

Thank you

I dont know Adaptronic well enough to know what sync strategies it has available, but the first place to look would be what the trigger settings are set to in the map. Typically with a missing tooth crank wheel the position of the cam "tooth" is not that critical - so I think it is unlikely cam belt stretch.

You have some significant looking spikes of noise in the crank waveform in a couple of areas so I would say this is more likely your issue. I've marked in green in the pic below.

Probably not relevant, but I will also mention that doesnt look like a pattern from a stock RB cas in your scope either, have you actually pulled the lid off to look? An RB cas should have a rising edge every 120deg for the inner slots. If you count the crank teeth between the middle and right hand "tooth" you have about the correct 120deg, but between the middle and left tooth you have more like 220-240deg.

In the "old days" when ecu's couldn't do the Nissan 360 trigger it was common to modify them with that aluminium foil tape stuff. We would use the inner 4 or 6 slots for the "crank" signal and we would make a foil tape "doughnut" to cover the outer slots, stick it on, then drill a single hole through it for the "sync". So you effectively ended up with a 1 tooth per TDC event on the crank and a single "home" on the cam. Im just telling that story to suggest there is the possibility that the CAS disc was modified in a similar way at some stage to act as a single slot - and some of the tape has come off...

Thank you so much for taking the time to reply Adam.

You have made a couple of interesting observations.............

On close inspection the crank sensor has a few metal particles stuck to it so that may account for the noise.

I have not removed the CAS yet as I wanted to understand a little more before I did.

It would appear that receiving multiple home signals from the CAS could well be my issue and as you have mentioned is not desirable. Thats what I needed to know before I proceeded further.

Without the CAS connected - refer below I get a fairly reliable and understandable pattern - clearly counting up to 720 and resetting on the missing teeth.

With the CAS connected - refer below I cannot properly understand what is happening to the displayed engine angle - multiple CAS pulses seem to be interfering with the engine angle count and going a little crazy

I needed to have a better understanding of the fault before replacing the CAS with one of the aftermarket single pulse reset units.

From what I have read I just need to make sure it pulses not at the same time as the missing tooth reset

PS

I have a background in Industrial Electronics but have never needed to fully understand the ECU function in my 260Z as it has performed faultlessly for at least 4 years.

I knew I could not fix it without understanding how it was meant to work - so I have had to learn a lot fast !

Again thanks for your help - much appreciated

Leigh.

I highly doubt there is any issue with your CAS, you still have massive spikes of noise on your crank signal, so that is your main issue. By all means fix the multiple teeth on the cam that most likely arent meant to be there, but there is no sign there is anything wrong with the CAS so dont waste time and money replacing it.