Crank Angle Sensor replacement help please!
 

Does anyone know how to change the CAS? If so, i would greatly appreciate any help with this! Is this something i should try an tackle myself or leave it for the dealership to charge something rediculous? Any help is appreciated! :icon_tup:
How could i get ahold of a service manual that may show me how to do this in a pdf form? Thanks guys.

what makes you think the crank angle sensors are bad? they rarely fail. you would have to put an oscilloscope on the G and Ne sensors to know for sure

The dealership told me one was failing. So im replacing both with the ones i found on ebay for 45 bucks. All symptoms were there too so im pretty sure this is it.

You took a single turbo FD (the one in your sig) to a dealership? What are the symptoms? What is your full list of modifications?

Crank angle sensors don't fail on these cars. Now I'm sure somebody somewhere on the internet may say that his CAS failed but in your case it is most likely a mis diagnosis from someone who doesn't know much about modified Rx-7's.

Tell me, what are the symptoms of a bad CAS on an FD? I've NEVER SEEN IT HAPPEN. EVER. Maybe if you took a sledge to one...

Only because it was close and it had to be towed. The symptoms ive experienced are shaking while idleing, smoke, sounds like its bogging kind of when revving up and wont stay idleing. In case its not the CAS is why im trying to figure out how to do it by myself because im not paying these guys 250 to put them on if its a fairly basic repair. We will know monday or tuesday if this is the prob or not for sure. What do you suppose it is?

it may just need to be tuned (rich, poorly adjusted idle). What do you have for engine management?

fc commander

i completely agree w arghx.

the CAS is just a magnet. find someone who actually knows modded FDs.

howard

Just a thought.....on your firewall, just behind the throttlebody there is a small black sensor just over 1 inch square labeled "sensor boost". It should have a single small vacuum hose going to it directly from a nipple on the passenger side of the intake manifold. Make sure that hose is in place at both ends.

amen, you got some big ole primaries that don't help idle, check the map sensor too, mine behaved similar when I forgot to plug it back in.

The dealership should have turned away the car. They have no businesses working on a modified car that doesn't even have the factory engine computer.

To Change the sensors:

1. Remove both drive belts.
2. Disconnect Neg. bat. terminal
3. Remove Idler pully assembly
4. Remove the E-shaft pullies and trigger ring. Do not remove E-shaft center bolt; the pullies will come off by removing the four 6mm bolts and the E-shaft lock plate.
5. You should be able to get to the two electrical connectors on the sensors. Make sure the connectors are identified as to their sensor; they are two different colors.
6. Remove the two 6mm bolts holding the sensors and remove the sensors.
7. Reassembly is the reverse. Make sure the trigger wheel is correctly on it's pins and the pulleys also seat over their pins before installing and tightening the four bolts.

I'm with these guys that it is unlikely these sensors are the problem. however they are not too hard to get to.
http://s1012.photobucket.com/albums/...t=IMG_1979.jpg

I'm surprised they didn't try to sell you a new engine and turbos. For 10k.

You're wasting your time if you replace the CAS based on those symptoms.

At the shop we had a car that usually wouldn't start, and when it would run it would spontaneously shut down. Aside from this, it idled fine while it ran. Ended up being bad wiring at one of the CAS connectors on the original wiring harness.

Thanks for all of the input guys anyone have a service manual on pdf so i can tackle this by any chance? Hope its something small not the seals!

Cleverly posted on this site. PDF searchable format. https://www.rx7club.com/showthread.p...ght=searchable post #10 is the money post.

ttmott pretty much summed it up. They are easy to get to.

That said, have you checked the map sensor yet? That was my first thought as well, and I also agree you should take the car to a known good rotary mechanic to have them diagnose this issue for you. I am not saying it isnt the cas, but it is a bit of a stretch.. <-- Just like 3 very knowledgeable rotary mechanics have already suggested..

Not only the MAP sensor vacuum hose, but also its electrical connector... loose contacts?

Is this map sensor and sensor boost the same thing? If so ive checked i unplugged it and plugged it back in and checked the hose everything is good. Problem still continues. Thanks for the help guys i trust you all more than the dealership so im going to pull the car out and get the cas switched since i already bought the new ones but ill keep u guys posted .

the map sensor is the thing that's plugged into part of the harness on the firewall, has a vacuum hose and 3 wires coming out of it. I would check to make sure the hose attached at BOTH ends and isn't t'd into something and not plugged into some random nipple. Some of the vacuum nipples are just passthroughs and aren't open to the inside of the intake manifold.

Yes. Map (Manifold Absolute Pressure) Sensor and Boost Sensor...same thing.

Thank you. checked it, everything is secure on the map sensor.

you're in over your head, you need to take it to someone who specializes in modifed FD's

Isn't rotorsports racing in your neck of the woods?

I'm just curious, you didn't mention how/when the problem occurred.

Have you done the basics of checking your spark plugs for fouling and doing a compression test?

I'd check the wiring harness from the ECU end of the harness through the CAS plugs. On a '94 Rx7 the CAS plugs are grey and white. Each one has two wires. Grey CAS plug has red and white wires. White CAS plug has red and yellow wires. Both CAS plugs share the same red wire. The red, white and yellow wires all trace back to the same yellow ECU plug. It's the top plug on the back of the ECU. If you unplug this yellow plug you can continuity test the three CAS wires. Here are pictures of the red, yellow and white CAS wire locations on the top ECU plug.

Red

White

Yellow

Obviously you'd put one meter lead at the big yellow plug and the other on a CAS plug. Then check for continuity.