The Trials and Tribulations of the C.A.S. (Cam Angle Sensor)

Lotus and Isuzu owners seem to have their unfair share of faulty sensors, the well known `Cam-Angle sensor` problem is feared amongst owners everywhere, the great expense, time and lack of performance for this rather unassuming little sensor makes for many a large credit card bill or overdraft.. But never fear, I have taken the bull by the horns and it'll cost you around $0.00 or in English money 0.00ukp  ( Given you've got the necessary tools, or can borrow them )..

OK first off, can you answer yes to most of these questions..

1. You fraudulently went to another Lotus dealer in your area, (not the usual one) and pretended to be giving them your business, with the sole intent of getting them to plug in their little ALDL (Assembly Line Diagnostic Link) and get them to tell you the code. (type 41)

or

1a. You stuck a paperclip between two pins of the ALDL and counted the little flashing lights on the instrument panel. As per the Lotus FAQ. (type 41) 4 flashes a pause then 1 flash.

2. The performance of your Elan is like a bunny rabbit, still quite fast but hops like a frog on LSD, and the Eastbourne ZimmerFrame relay team can overtake you.

3. Can't rev above 4000rpm (reported by some owners, doesn't always apply- didn't in my case)

4. When idling the RPM doesn't stay at a constant 1000rpm (it ought too, the EM should make it), it oscillates.

If you answered yes to most of these, chances are your CAS is out, especially given No 1. or 1a, what to do in these circumstances..

1. Go to your local Lotus dealer pay $210.00 + labour charges for approx 1 and 1/2 hours (probably around $60-$100 per hour)

2. Go to your local Isuzu parts dept. and try and persuade them that it really is an Isuzu part and they do have it. (Good Luck)

3. Buy the expensive ($200) parts manual for the Elan and spend an evening trying to find the exploded diagram of the CAS assembly and be unable to find it anywhere (Clue: Its not there!)

4. Fix it yourself.

Disclaimer: I'm telling you not to fix it yourself, take it to the dealer and pay for them to do, I have fixed mine successfully, I know of one other guy who did too, using his instructions. I'm serious you could bend the cam interrupter flange or worse, only do this if you're sure and then still don't do it. I'm not responsible at all, ask anyone who knows me, if you follow this you're as crazy as I am . .  Sorry about this but I now live in America and here they sue for they're own stupidity so I'm being cautious here, I want to save you money, but I don't want to lose mine 8-) ..

If you choose #4 I`d suggest the following:-Do you know the difference between a car engine and a strange lump of metal and rubber that sits in the front of your car? If so gather the following:

• a soldering iron (around 15watts small tip), yes that's how you spell it
• solder, small gauge will be fine , I use 60% tin , 40% lead, rosin core "44"
• brains
• a 5.5 mm ratchet socket
• some rubber sealant, or other sealing compound (must be non-corrosive to copper and etch board, as well as non-conductive, plus be heat resistant and capable of hermetic sealing.) I used some Loc-tite black adhesive sealant that I used for putting back the little panels on the door.  I don't know if this is non -orrosive to be honest, it has some acid in it, I`ll have to wait and see. YMMV..
• some contact cleaner, again non-corrosive, no residue leaving etc.
• a small stiff hog hair brush, not a metal bristle type.. I found it next to the contact cleaner.
• a friend who knows how to use a telephone and call the emergency services ..
• X-acto knife
• small vice (not that kind)
• about 1 hour..
• a broken Lotus,. or Isuzu Impulse 4ex1

Note: About the battery, car batteries can supply a fair amount of amperage at 12volts, enough to do some serious harm to you, at least its DC though, you probably should remove the correct lead from the battery, see owners manual, before attempting any work. Be warned though that this can throw off your cars computer, it might get rid of all the information the computer has learnt about your engine/fuel mix etc. Sometimes that can be a good thing, depending, it`ll take sometime to relearn it, .. I didn`t remove the battery, that way i didn`t have to worry about clearing the computers memory, the sensors aren`t under power when the engine is of, (as far as I know), so they won`t get damaged. However its safer to work with the electrical system dead, even when the engines off theres still juice running around. Be careful, use good judegement..

The Procedure

 First pop the hood, its better if you do it when the engines cold, the EGR pipe gets very hot and it just happens to be about 1-2 inches away from where your fingers will be.  Wear gloves- engine compartments are carcinogenic ;-)  .. See the diagram in the car for which is the EGR.

This is Doug`s car (Av8ndoc@aol.com),  I`ve drawn a box around the plastic housing. Remove that. Isn`t dougs car cool with the colour coding..

Locate the Sensor housing, stand in front of the engine, look at the big shiny thing that says ISUZU-LOTUS, to the right of that (the cam cover) there's a black plastic cover,its got a round extrusion coming out of it, and at the back of it there's an electrical connector, above it is a little metal box, ignore that.

See it here below , these pictures are pretty big, but iIthought its better that way so you`re sure! Its the thing in the centre of the picture.

Pretty messy huh.. Look at all that oil.

Ok there are 4 bolts that 3 of are easy to get out, the other is a little tricky, I picked up a ratchet that could bend to get to it. Take your time with it, don't strip it. Its slightly rounded so you can use a closed head spanner/wrench to wiggle it free.

Remove the plastic cover, You ought to see a large round disc with cuts laterally across it, if not put every thing back to the way it was and look for the right cover dummy.. You'll see a black plastic thing pointing down at the disc. This is the other part of the sensor, I think its a timing/position sensor, given the cuts.

Under and behind the disc is another black plastic sensor, it has three little plastic extrusions, and if you look at the metal disc, you'll see a metal flange coming out of back, this passes through that sensor and tells the computer when each turn of the CAM happens, its a hall-effect sensor, a little magnet and pickup inside those extrusions.. Its not the one pictured above, the one that points at the edge of the disc..

Heres the side view of the hall effect sensor. You can see one of the bolts clearly..

Here are some pictures of it after its been removed..

Sorry the pictures are A) a bit dim and B) out of the engine 8-) I used my IndyCam and i`ll be damned if I'm dragging my SGI out to the garage to take pictures of it )

You can just make out the three extrusions.. But we're jumping ahead a little here, ( and here's one I made earlier ).

Ok locate the above sensor, there are two bolts holding it in place, ones easy the others quite tricky to get out, a little patience and small hands works wonders here, so does a bendy ratchet. Get one of those bendy gripper things to retrieve things that have fallen into the engine, very useful , frys again. Pull out the connector from under the sensor, its locked in place by a tab, lift the tab away from the sensor gently, its just plastic and although quite strong, it could snap and you don't want that do you..

Heres a side view showing the clip, its the grey thin tab that goes up the black part. Thats the EGR pipe in front, watch out for it.

Insert a screwdriver between the tab and the sensor and twist gently, pulling downward on the connector and *not* the wires going into it, these wires are not that strong and the connector can be pulled apart easily, so use the plug housing. After you've removed the two bolts and the connector you should be able to lift the sensor away, note where it is before you do that, you may even want to mark it with a white pen or tippex/correction fluid before you even unscrew it,. it doesn't matter if you don't but it may help later (just be careful not wipe off the mark as you handle it)

Ok the sensor itself is probably not that ESD sensitive, that's tech talk for static electricity, if you're one of those people who blow up electronic devices just be looking at them hold onto the engine as you lift it out, take off your gloves first, don't hold on to the EGR or any other hot part, and make sure its metal, and don't wear gloves for that part !!. This will discharge you of any static buildup. I doubt you could destroy the sensor short of running it up and down a van der graaf generator, but might as well take care..

Next you'll see the shiny black compound on the sensor, its fairly soft to the touch, now *very* gently get a sharp exacto knife and cut around the outside of the rubber stuff, don't cut too deeply yet, do it just under half as deep as the sensor, (approx 2.5-3mm) , at the end of the sensor that's not where the connector is you can cut all the way to the bottom, there's no wires or circuits, don't go mad though! the circuit board comes down about 7mm from the connector end so take a lot of care in that area, here's a picture of it..

Unfortunately not a great picture, but you can see it I hope... I've marked the red area as where the circuit board is, take extra care here and do a little at a time. The blue area is just rubber compound, don't go too deep though the magnet is in the extruded part, if you don't go deeper than the shallowest part you'll be ok. Remove the rubber a bit at a time, It takes a little work but its quite doable... You run the risk of cutting up the circuit board which is fairly delicate so be careful around it..

Once you've removed as much of the rubber as you can spray it with the contact cleaner and brush it with the hog brush to get rid of any residue, clean iit as much as possible especially around the pins at the top end. (there are four in a row, one doesn't have any solder on it), the rubber will interfere with the soldering process, so be sure to make it clean, don`t rub so hard that you scratch off the resin coating.

Once its nice and clean.

You can see the pins i was talking about, yes I know they are at the bottom in this picture.. who knew.. not that it matters. in this case. You can see I scratched the circuit board a little at the top edge, oops if you want to be really safe get some resin from frys and paint it over, if you do that, it will protect the board ( don't do it until the end though, just before applying the rubber compound ).

Ok next get the soldering iron, a small 15-20watt iron will do fine, with a small bit, don't use one of those solder guns or a welding torch.. you're not arc welding here. We then cover the tip of the soldering iron with some solder or flux, depending on how old you are, don't go mad, if it beads its too much, start again.

Get the tip of the iron nice and shiny, if its dull clean it on a wet sponge and try again, touch the iron to each of the solder pads (the little silver blobs) and wait for the solder to melt, it'll go brighter. now this takes practice, but look for a pin that doesn't look quite right, usually when soldered joints go bad, (dry joints), you'll see a change in the solder at the point where the pin comes from the middle of the solder blob, the one on the leftmost at the bottom is the bad one for me, you can't see it too well in the pic, but its visibly different from the others, it looks disjointed, and it is.

Now to get rid of that you must get the solder to adhere to it, usually this means getting it hot enough to join, a second or so from a 15 watt iron will do, a higher wattage iron requires less time, add a little fresh solder to the joint and it ought to flux together, ..

If you really want to do a good job get a solder sucker from frys or any electronics store, its a mini suction pump, you melt the solder on the joint , put the solder sucker on it and press the button and it sucks out the solder, leaving a nice clean pad, it might take you a few tries.

Then resolder the joints, do all of them , take more care with the 3 smaller ones, you could damage them with excessive heat, again take your time.. it'll be fine.

As a tip practice soldering on your new computer, just kidding!!, just get a couple of small SWG wire strands and solder them together, practice till you can control the amount of solder.

Don't join the pads together that's a no no make sure there's 6 visibly separate pads, check very carefully with a magnifying glass after you've done all of them, look for solder that's gone across the joints,. remove if there is any..

Ok you can apply resin to the board if you so wish now...its not needed really , unless you've heavily scratched the board, it will protect it and make it last longer, let it dry though..

See how nice and shiny the joints are now! this is what yours ought to look like ...(its shinier in real life)

Replace the sensor in the engine, take your time with the screws. try and line the sensor up with where it was before, now see that metal plate sticking out of the metal disc , that has to pass through the top slot, so what you have to do (when you're reasonably sure its in the right place) is first make sure you're not on a hill, put the handbrake on ( if you're American, you probably haven't got it on already ;-) ) put the engine in gear (1rst) and take the brake off, again make sure the car is on a flat surface before doing this, its wise to have someone else around who isn't involved to call 911 if you let the car run over you..

Watch where the metal flange is. Rock the car gently forward, don't let it roll back otherwise the cam will move forward then back, the idea is to get it to go forward very slowly, its quite heavy, do it gently though, small steps, get the metal flange as close to the sensor as possible make sure its going to be able to pass through the top slot, not the bottom one as this does nothing.. when you're sure roll the car forward an inch or so, the metal flange should go into the slot, if there's a scraping noise and little bits of plastic, call your local lotus dealer, ok check the clearance between the slot and the flange, it should be even on both sides, if so, roll the car forward again and check the clearance as it leaves the slot, not the car the flange) if its not clear adjust the sensor so that it is,,

Ok now when you're completely happy with the position of the sensor , you may want to push the car around a bit before this, tighten up the bolts on the sensor so they're nice and snug not to much or you'll distort the sensor and/or crack it. Make sure the sensor doesn't shift position, check the clearance again...

If alls ok, put the brake on, take the car out of gear into neutral, and give the starter a quick turn, don't let the engine start just give it a quick twist and let go, If you lean through the window you can keep an eye on the sensor, for gods sake make sure the car is out of gear and the brake is on before you do this...

Ok check the flange , is there any plastic bits on it, no ,  then good, if there are and its just a little chances are the clearance is slightly off, adjust as before.

Ok start the engine, go round the front and  watch the cam with your eyes and not your hands , stay away from it, its metal, sharp and spins fast, you need those fingers!. There shouldn't be any scraping or other noises.. Go check the instrument panel , the engine warning light ought to be on, if it isn't you either jumped ahead or you're doing the wrong sensor.. Turn the engine off, be careful of the EGR again, even a short engine run will heat it up..

Connect the sensor plug again, its dangling below the sensor hopefully, unless you  wrapped it round the cam wheel for safe keeping (don`t do that). Its tough to get in tight, make sure it mates correctly and the little notch gets seated it should be a snug fit. You will have to push it quite a bit to get it in.

Ok again, take the usual precautions , switch on the engine, hopefully the engine warning light won't come on, if it does you've either got something else wrong with the car, check the code, or the connector isn't plugged in correctly, or you botched the soldering job 8-) . Take it off again and check the soldering, get someone who knows how to solder this time.. or maybe the sensor is frizzed take it to the dealer and get another (unlikely), make sure the engine is off...
 

Remove the sensor again , what!, get the rubber compound and cover the circuit, (after you've checked it all works of course), use a piece of card to make a nice flat surface, let the compound cure, usually touch dry within 15 minutes, 1 hour till its set enough to replace the sensor and 24 hours to completely dry.

After the compound is applied, like the gloves?

Replace the sensor as before, taking time to make sure its seated correctly and the metal flange goes through the air between the slot and not the slot itself.

Reconnect the sensor plug, start the engine, if the light doesn't come on hurrah that's it , well done... Switch off the engine, replace the plastic cover with all the bolts!!, nice and tight and that's it. you've hopefully saved a few hundred greenbacks. I know I did...

if things aren't going well , backtrack, take your time check everything, aligning the sensor isn't that difficult just check and recheck, time spent now will save money later.

Remember: Check, Check agan and Recheck.. Engines and Camshafts spin at very high speeds, they`re metal if they hit other surfaces you could be showered with little metal shards, not fun.

if you're stuck, don't understand this gibberish, drop me a line charlie@charliex.net i`ll be happy to help, unless you're asking me to pay for the damages you just caused or medical bills etc ....

You might want to clean these pins too, use the cleaner from before and the brush take care not to bend them.. cleaning them won't hurt, its a good practice.

Have fun, mine worked great, saved $ 350 bucks, drove to the service center and said hey Ted cancel that part! I fixed it myself 8-) and with that I lowered the hood and drove off into the sunset with my dog molly, of course five minutes later we stopped and put the hood back up coz its freezing !!!

Did I forget anything, screws left over, unclear instructions then mail me -> charlie@charliex.net

. Charlie .