Crank Angle Sensor

Introduction

The RB30E Crank Angle Sensor lives inside the distributor housing. The ECU relies on it for timing. There are at least two types of distributor, Mitsubishi & Hitachi. Possibly Mitsubishi is more common on the Nissan RB30Es and Hitachi on the Holden RB30Es? Please correct if you know.

Here's an explanation from Haltech (IIRC):

Here's a stylised waveform of the Nissan CAS output from Adaptronic (IIRC), this one for an SR20, RB30 similar, but obviously 6 cylinders:

Symptoms/Diagnostics

One red flash, one green flash, code 11, Crank Angle Sensor fault. Expand.

A faulty CAS can cause all kinds of problems, from turning all the milk in the village sour to Amazonian deforestation. Sometimes the engine will not idle, or will idle poorly, or will cough & splutter, or will not rev, or will die unexpectedly. A faulty AFM can cause an overlapping set of faults. If your engine is behaving like a dog, and you've got a CAS fault code, the CAS is a good bet. If you've access to a spare distributor, you could swap that over (for the different CAS that it contains) as another test to tease out the problem.

Removing The Distributor

Remove the airbox snorkel. Remove the intake piping between AFM and crossover pipe. Pull all the leads off the distributor (the cylinder numbers are marked on the distributor). Remove the CAS plug (you need to flick the wire clip out of the way). Remove the earth wire clip next the the CAS plug. Remove the power transistor plug (left of distributor body).

Remove the distributor cover. This rotor is facing TDC for cylinder 6, if it were facing the opposite direction it would be TDC for cylinder 1, anyway it probably won't be lined up correctly when you take it off. When you do have it lined up, take a photo for reference later.

So you have to move the engine (either by moving the car when in 5th gear, or cranking the motor) to TDC before you pull off the distributor. The point of this is to have a reference for when it goes back together, because it's not keyed. If you could guarantee the engine wouldn't be moved in the interim, you wouldn't necessarily need to do this, but if someone cranked the engine by accident, this gives you a fighting chance at realigning everything. Take the negative lead off the battery anyway. (If you did have to find TDC again, there are a few ways to distinguish between TDC cylinder 1 & TDC cylinder 6. One is to take cylinder 1's sparkplug out, and put your finger in the hole. Your finger will be pushed out on the compression stroke as you pull the car forward, then you know it's TDC cylinder 1. Another way is take the top timing cover off and make sure the dowel on the cam gear is facing straight up.)

Also scribe a line where your current base timing is. Even if you are putting a new distributor back on, you can copy this to the new one to get a timing reference.

Undo the bolt and pull it out. You can see the drive gear on the left. Because the gears are helix cut, the rotor will turn as the distributor comes off, so when you reinsert it, you have to reverse it a little, so that it finishes in the correct position. (Apparently there's a mark on the drive gear that lines up with a mark on the distributor to show the right start alignment, but I missed it.) A photo of the correct position before you take it off is helpful.

CAS Removal

Removing the distributor is not necessary when replacing a CAS unless the bearing is busted. Please note that although these pictures are taken with the distributor removed, all work done is possible whilst it is still in the car, and was indeed done once the CAS had been harvested from the donor used in these pictures.

Tools Required

• Subway Cookie
• Glass of Coke
• Meaty Phillips head
• Flat Head
• 8mm Socket on ratchet.
• Small Electronics screwdriver (not pictured)
• Telescopic Magnet (optional, I dropped a few screws and had to fish them out from around the power steer lines)

Procedure

First up, remove the distributor cap and rotor button with a screw driver and an 8mm socket. Having the car at TDC is not necessary, just aim it so the bolt holding the Rotor Button is easily accessible.

Next up remove the inspection plate, the two screws holding it on are a little bit weak, so if a Phillips head is looking like its going to round out, switch over to a flat head to crack it.

If you are just doing this as a minor troubleshooting method, or don't have a new CAS and are just going to use a second hand one then before you proceed, blast the buggery out of the CAS wheel and sensor with some contact cleaner. Don't use anything else, this stuff is a million times better than Brakleen or WD40.

Now, about the only difficult part. You now need to undo the screw in the center of the spindle. Odds are it will be as tight as a ducks butthole, so be really careful not to strip it, because it will be quite hard to remove otherwise.

Now remove the wheel, be careful with it, however do remember that both the spindle and the wheel have a flat edge so they will locate back to their position correctly when you reassemble it, and that if you drop the wheel, make sure the markings are on the outside (there are numbers stamped on the top side)

Now remove the two screws topside on either side of the plug.

Now for hard part #2. Getting that dick of a black brittle plastic thing off. Your best hope is that you break it in two pieces not 4 or 4 million like I did. (if anyone knows how to remove it without breaking it, hit me up!)

Ok, now remove the 3 long screws and the inner spindle.

And bam, she's out!

Now put your new CAS in, (if the bearing is naffed, you will have to have it replaced, basically if the inside of the distributor around the CAS is covered in red dust, it's probably got a buggered bearing.)

To install the CAS, reverse the procedure, once tested, smash the buggery out of the old CAS with a hammer and thank Nissan and Mitsubishi Electronics Co for blessing us with such a strong easy to get to and vital unit.

This is what a buggered bearing will end up looking like.

The Crank Angle Sensor

With the rotor and CAS cover off, you can see the chopper disc and photodiode assembly on the left. The chopper disc has six holes (one square for home) one for each cylinder, then 360(?) slits for measuring to the nearest 2 degrees. It seems incredible overkill. There's not much you can do here except say "oooh, aaaah". Tune in next week, same bat time, same bat channel.

And then a miracle occurs. Here is the bearing that lives inside the distributor. After 17 years it was completely dry and rooted. Here is also the bearing number for the replacement. Even if your CAS is perfectly fine, your distributor may be making horrible noises because of this bearing. My horrible noises were particularly noticeable at 1500rpm, and with the bonnet up it was easy to hear it was coming from the distributor. If the bearing gets bad enough it can destroy itself, and fragments of it can end up in your CAS chopper disc, so it's a good idea to change this as preventative maintenance. You probably need a press to get this bearing out, you could hammer it with a punch, but it's not very elegant. I got the auto sparky who sold me the CAS to change the bearing too, as I had no press.

Here is the old CAS assembly. The old chopper disc gets used again. Basically you undo the big screw holding the shaft on, and get the chopper disc out of the way, then this all lifts out, and Bob's your uncle. It's all potted in epoxy, fairly solid construction. I was thinking about dissecting it for educational purposes, but I decided to keep it in the car as a dodgy backup. You can also see the ACA part number. The sparky who sold it to me said they're good (he would), and it's got a two year warranty, so we'll see (touch wood).

If you look in the slit under sunlight, you can see the little windows inside for the LED/photodiodes. I tried and pretty much failed to take a photo. On the left rear there's three slits that read the outer fine slots in the chopper disc, and on the right front there's one hole that reads the inner six cylinder marking slots.

Contributors

PreStagea, Gavin

Notes from the Forum

• The VL Commodores with RB30E came with Hitachi CAS/dizzy units, whereas the RB30E fitted to the R31 Skyline came with Mitsubishi CAS/dizzy units (post 12/86 - according to FAST prior to this date was Hitachi unit). The complete units themselves are interchangeable, however the dizzy cap&rotor, CAS assembly, and distributor shaft seal differs between the two -- be sure to check which brand CAS/dizzy you have before ordering parts.

• Under the bearing depicted above, is a distributor shaft seal, and it should be replaced at the same time as doing the rest of the work here. However, there are many online sources referencing seal part# 408033P as fitting the R31/Mitsubishi setup, and this is incorrect - that part is for the Hitachi CAS/dizzy. See this thread for more info -> https://forum.r31skylineclub.com/index.php?topic=159929.0