Anyone know the air gap (s) on the crank angle sensor pick ups? and how critical is this clearance??

 

check the FSM' s https://www.rx7club.com/1st-generation-specific-1979-1985-18/download-copy-your-year-fsm-click-thread-get-link-894736/ You will find everything there you want to know including the year and what you have

 

Use a business card or piece of thin card stock.

Not overly critical as long as it is close enough to get a reliable signal.

Though, it kind of depends why you are asking...

 

I'm, asking because I fear it may NOT be getting the correct signal.

I have one CAS that shows .006 on both uppper and lower pickups, and the other one I have has around .010

Also I'm wondering which one is more piticular , the pionter or the wheel??

My car may be interpriting the wrong signal, or a signal at the wrong time, causing an advance spark...BUT only on one rotor???

Rick

 

Hi Rick I think the measurements you are giving are a tad close if anything you should be in the .020 to .030 range .006 is a little close with a little wear it would almost touch . Inside the CAS the ( pointer ) is what triggers the ignition .. If Aaron told you about a credit card width is ok then it is . My credit card measures .031 and I also read in a thread somewhere that .030 is the number . I would think that too close is worse than a little far because it wouldn't get as good of a field built up if it is to close . ..To test your pickups unplug the CAS 4 wire plug , if you look on the white plug on the CAS side of the plug you will see G1,G2 NE1-NE2,,, place the meter probes in G1 and G2 it should measure between 110 and 210 same as between NE1 and NE2 should measure between 110 and 210 but I don't think they CAS gives problems very often .. Explain what your engine is doing that makes you think that you have CAS problems.. If you explain it well these guys almost know what is wrong before they are done reading

 

Are there any problems you are having with the car?

The reluctor conditioners in the stock ECU are actually very good. Disturbingly good, in fact. I've retrofitted 13Bs into other vehicles and have used non-shielded wires run right past ignition coils (not my choice, believe me!) for the CAS and have not see any interference. So as far as the gaps, it isn't that critical. Now that's not to say that perhaps your CAS isn't bad...but in my experience, bad CASs have always ended up being the harness connectors.

Helps to know if you are trying to troubleshoot something though.

 

Thanks, you guys are really into these things, I'm impressed, for a minute I thought there might be a bunch of misinformation from folks not too keen on real tech stuf, but I was wrong, and I guess that puts ME into the not so keen catagory

Well anyway, I have a thread on "rear seal blow out" if ya wanna know my real problem! it's ugly ! and I really do need serious help, from serious Mazda guys.

Anyhow, Jim Langer from RB says he thought the cause of a 4 motor, rear rotor ONLY, blow up was electrical, and he suggested the CAS, or the ECU, so I starteds to look iinto the CAS and found I did have a gap veriation between the two CAS's I own,...hence the gap question.

Thanks,
Rick

 

It is possible that your issue was due to ignition noise, but very unlikely especially in an NA. Then again, it can't hurt to check. But the gap in the CAS likely isn't the issue.

If you have a scope, record the signals from the two reluctors (at the ECU) and check for noise.

Honestly, I've never seen CAS noise issue with the stock ECU though.

I'll take another look at your other thread when I have a bit of time and see if I can provide any new information based on the new posts.

(Yeah, I was into electronics long before rotarys so EFI is old hat to me. )