So I'm having trouble aligning the CAS. I know this is a done-to-death thread topic, but I've searched and I'm 100% certain I'm doing this correctly. The results are still strange though.

When I turn my engine to the yellow mark on the pulley and align the CAS pointer, it installs in this position.



I've tried removing it and reinstalling one tooth forward or back, however it only actually aligns with the front cover stud (bolt in my case) when I install it this way. I would have expected it to center properly more / less.

Then when I start the car, get it to idle at 750, jumper the initial set connector, and use a timing light, it wants to be all the way to the other end of the slot. It runs fairly normally except the shifter vibrates a bit (went back to rubber mounts so the problem could have been masked by the poly mounts I had before) and I think it's a bit slow to rev. I'm not 100% sure since it's been so long since I drove this car, but it feels like my Celica revs faster / as fast in neutral. Which doesn't seem right to me.

To add further confusion, I have a different CAS that always wants to install in the opposite way; Starts at the back of the slot, needs to be advanced all the way to time properly according to the light.

Every post I read indicates that simply aligning the CAS should put it within 1-2 degrees of the correct alignment, but I'm probably 5-10 degrees out at least. I can't even see the marks until I rotate the CAS all the way to the side. I've heard the Rx7 CAS is bulletproof, but I'm beginning to wonder if I should try and find a third one to try. The only other possibility is that the drive gear is backward on the eccentric shaft, but the previous engine had similar issues so I'm suspecting user error or possibly just two bad CAS units (although frankly I don't know how such a simple device could fail this way). Not sure if ECU failure could be a possible cause but I do have a spare someplace that I could try.

Any help is appreciated. Thanks, Chris.

 

Couple questions, so I'm up to speed with you.

How are you aligning the cas? Are you looking where the top magnets are in the sensor, or are you using the mark on the gear at the bottom?

The reason I ask is because it took me a couple of times to figure it out and I was always a tooth off. I ended up getting it by aligning the mark on the gear, then finding something to hold the cas shaft stationary so it wouldn't rotate in the housing. Clean and lubricate where the cas goes in. As you lower the cas down, you should feel when you start to contact the timing gear. The cas will want to rotate a little bit. If you are close to the middle of your clamp, you should end up with plenty of adjustment. Not sure if this is your problem, I hope this helps though.

Are you installing the jumper with the key off, or running? I always do it with the key off because I don't know if there is a small boot cycle in the ecu to detect it. The greybeards would know more.

Is it the correct timing mark? I repainted mine so they show up better.

Where is your tps zerod to? Is it throttle fully closed, or just partially?

Also, I gapped the pickups in my cas to around .010-.015"

I don't know if these will help you, but they might be good to check. Hope this helps

 

I've tried the jumper both ways but don't see a difference. I've been starting the car with it already jumped just for consistency.

I've been aligning it using the little dimple on the bottom gear and the pointer. Then I look at it from the top as I try to seat it, making sure the CAS gears stay in the right position. I can try stick a screwdriver on either side to keep it stationary, but I'm fairly certain I'm getting that part right.

It's like there is no "notch" on the drive gear in the middle of the adjustment. Only at the extremes.

TPS is good, I have it adjusted at hot idle per instructions. I use the test lamp method since I find it most accurate.

I feel like I'm missing something simple here. Everything should be working. Align the gears, don't let it rotate relative to the magnetic pickups, install it, timing light. But something is just a bit off.

The part about gapping the pickups though is interesting. Is there an FSM spec for that? I always figured they were non-adjustable.

I appreciate the help

 

So I tried using a screwdriver to hold the gear in the same place while installing, same results. Interestingly I tried my backup CAS with the screwdriver method and it now installs just like my other one. So there's isn't much deviation between the CAS units after all.

As for the timing marks, I'm not sure. The paint was long gone so I found the two little divots in the pulley and marked the first one with some paint. But thinking about it, I am fairly certain this engine is rebuilt and so I can't be sure the hub and pulley are still a matched set. Which is a problem since my old engine was a mystery engine as well and therefore also had a pulley and hub that may or may not have been matched. So I don't have a hub and pulley that are 100% certain anywhere.

Either way I hope to eliminate every possible option that doesn't involve removing the front cover.

 

The plot thickens...



A yellow mark and a big yellow "L". Implying that maybe this is the real TDC and somebody used a different pulley that doesn't match the hub? My pulley has no marks in that area so maybe they made a paint mark and then it wore away. As you can see, it's at least 10-15 degrees out.

I made a new paint mark on my pulley to correspond to that and reinstalled it. Now when I install the CAS:



Hmm. That looks much more like it should, I think. I won't know for a few days until I get a functional timing light (both of mine are broken) and try starting it up.

 

It looks like you're on the right path. Do you have a way to copy the correct pulley marks to your stack? This seems like the prevailing factor here.

As far as gapping the sensor goes, mine rolled off my workbench one time and smacked pretty hard on the concrete. One of the pickups was moved all the way out. To readjust, you need a couple of screwdrivers. One screw is the pivot, and the other clamps the adjustment in. Slightly loosen the screws, but leave some friction on them. Take a flathead screwdriver and insert it into the notch at the end of whichever pickup plate you are adjusting. Use a feeler Guage between the pickup and the wheel and rotate the screwdriver until you get what spec you want. It's not in the manual, so I just guessed .010-.015" based on the lawnmower ignition I had worked on a couple weeks before. If we knew who made the sensor, we might be able to find a spec sheet on it.

PSA to everyone: If both sides are even and you haven't messed with it, Leave It Alone!!!!

 

WondrousBread,

Did you have any new findings? My CAS is somewhat similar. I can install it and it's fairly centered in the slot, but once I shine my timing line, I'm a quite a few degrees off. Once I turn the CAS and align my marks, the bolt is all the way to left side of the slot. I don't really have any issues once my timing is set this way, but I was always curious why my timing marks are so off when I restab my CAS.

Interested in your findings.

 

My only findings were that the car ran when I stabbed the CAS in the new location I found marked on the hub, but was misfiring a bit and sounded a bit "manic". I'm not sure the word, but the engine makes a different sound when the timing is way advanced.

Anyways, then engine clearly wasn't happy until the timing was adjusted to the original mark on the pulley at which point it stopped misfiring and smoothed out.

My original symptoms are still there though, so my only real option I think is to pull the intake back apart and recheck everything. I'm coming up empty on other options at this point since I've checked literally everything that can possibly be reached from the outside and my engine is still a bit shakey at idle.

 

Couple ideas,

Have you checked to make sure your timing is on the right spark plug? I lost an afternoon not paying attention one time.

What state is your vacuum system in? Do you have your air bleeds still in place to set your idle correctly?

 

Sorry I let this thread languish, I had an unrelated thread yesterday that actually resolved this issue and so I wanted to post the follow-up here in case someone finds this thread in the future for a similar issue.

I realized that L1, L2, and T1 were firing at the same time. Meaning that the ECU was locking timing at zero split. The fact that it was way at the extreme of the adjustment suggested it was also changing from the usual 5 ATDC lead timing.

I dug into the training manuals (Foxed.ca), and found a page that describes what the ECU does with timing under various conditions. Most are related to the Automatic models but there are some for when the AC is running and when the Power Steering is turned.

When the AC is on, split becomes zero and both Leading (L1 and L2) and Trailing (T1) are locked at 10 degrees ATDC.

So I pulled up my carpet and backprobed the ECU. Pin 1E is supposed to be below 2.5V when the AC is ON, and around 12V when the AC is OFF.

My pin 1E is constantly below 2.5V. Come to think of it, back when I had the little condenser fan for the AC it was also constantly running. Presumably there's a switch someplace that tells the ECU when AC is on and mine has failed in such a way that the ECU is always told it's running (and presumably it's been this way since I got the car, four years ago).

The reason for the weird bog I had when getting onto the throttle was this: The ECU only does this adjustment at idle. So at idle I had adjusted the CAS all the way to the left to make it fire at the "stock" time (albeit with zero split), but the moment I got on throttle it would detect that I wasn't at idle and drop like 5 degrees of timing before advancing properly.

I added a temporary jumper for pin 1E to give it 12V and my timing now works as expected, with the CAS landing right in the center of its adjustment. Split is normal, advance works. Idle still isn't super smooth but I'm going to test the rest of the ECU pins and see if there's anything else I missed.

When I get a chance I'll upload a screenshot of the ECU pinout and the training manual here in case someone else needs this info.