Replacing a Bad Cam Angle Sensor
( If you haven’t yet, you will):

Introduction

The Cam Angle Sensor (CAS) as a unit consists of three parts. These are easily viewable on the car when removing the black dust cover. 1) the central spinning notched Reflector Wheel, 2) the Hall Effect sensor on the bottom which provides the timing reference for the injection sequence; and, 3) the magnetic pickup for rpm data. See Charlie’s writeup of repairing the Hall Effect sensor which has great pictures of these parts.

It is the Hall Effect sensor which causes the engine check light to come on and causes engine running problems. A Code 41 error is reported at the ALDL and turns on the engine check light when the ECM does not receive signal pulses for more than twenty engine revolutions or it does not receive signal pulses for more than 5 seconds. Read the Error code check write-up if you haven't already.

Below are four ways to repair this problem--listed from cheapest to most expensive. I recommend removing the CAS completely for each of these. Because in all cases (even if you only remove the Hall Effect sensor which has a stubborn right screw), you must still reset the basic ignition timing to ensure proper performance.

1. Read Charlie’s article on how to repair the Hall Effect sensor yourself. Cost is less than $10. However you should know what you are doing and if you screw it up your Elan may be down until you do 2, 3, or 4 below. (I have a bad one for sale; make me an offer--Carl)

2. Buy a repaired Hall Effect sensor from someone who is practiced on repairing one like Charlie. Cost should be less than $50. I will investigate a part number from Isuzu, but…

3. Find your nearby Isuzu dealer and buy the whole CAS for currently about $92 plus tax. This is by far the easiest method and will guarantee no Elan downtime.

4. Take your Elan to the nearest Lotus dealer and give them a blank check. A "genuine Lotus" (Isuzu) part will cost starting at $165 plus labor.

Here’s How You do it using the Number 3 choice above:

FIRST:

Find the Isuzu CAS part somewhere - Mail order it or drive to a dealer. The Isuzu part number is 8-01103-818-1 defined as from a "4XE1 DOHCTURBO (1.6L(1588cc)) 1991 Impulse RS, AWD" (From Vince’s Mar 26 message board posting- Thanks Vince)

If you are smart enough to get to this board then you are smart enough to jump to www.Partsvoice.com and do a parts search by manufacturer (Isuzu) and part number (above, but without the hyphens) using your state or zipcode to narrow down the search. I came up with 12 dealers all with one CAS on hand except for Cerritos Isuzu/Ford (in Southern California) which had 13 of the beasts - now 12! They can be reached at [Phone: (562) 865-1187]

Now that you have a new CAS - Prepare the old one for removal. Mark in your memory, or better yet on a stick, the approximate bolt position in the opening slot on the old CAS. Disconnect the two electrical connectors carefully lifting the locking clips; remove the one bolt and slowly twist and remove the old CAS. Now look at the offset slotted tongues position on the removed old sensor. Move the offset tongues on the new CAS to approximately the same position and install the CAS. It should fall into place. Reinstall the hold down bolt to the same position; connect the two cables and you will have a running Elan without check engine light! If the engine is really rough you can try moving the CAS up or down a few mm. Or in the worst case even put back the old one if you didn’t deep six it immediately.

SECOND:

It’s important to ensure that the BASIC engine timing is still set correctly because all parts and all changes are all just a little bit different no matter how you mark the old one. This can be done later at a more convenient time and place if you must. The ECU per the underhood placard will make all other necessary corrections for actual running conditions.

The tricks you need to know make it easy: It takes two people; you remove the passenger wheel and the inner rubber well cover and you can then easily see the engine timing marks; But you must put the ECM into the "Field Service Mode" either with the Tech-1 tool or via a paperclip shorting pins A and B of the ALDL (A is the corner black wire and B is the black/white wire next to it) with the engine running to lock out all the other sensor inputs. Then have your buddy set the CAS position while you use the timing light. Done easy!

Here are the same words from the service manual on setting timing--see the timing write-up for more details!

The base ignition timing is set by altering the position of the magnetic pickup relative to the reflector wheel, by rotating the cam angle sensor.

1. The engine-should be running at idle, at normal running temperature (cooling fans cycled on and off) with the air conditioning and all ancillary equipment (including cooling fans) switched off;

2. Fit the bridging plug TOOOT0909 {same as paperclip} into the ALDL connector ('Check Engine' light will flash), or use the 'Tech 1' tool to enter field service mode.

3. Slowly raise engine speed over 2,000 rpm, and return to idle slowly to reset the ~AC valve at the 20 count position.

4. Connect a stroboscopic timing light to the no. l spark plug lead, and using the timing marks on the front pulley, note the base ignition timing. Specification = 16 degrees BTDC (Before Top Dead Center). If necessary, slacken the cam angle sensor housing clamp bolt, and rotate the housing as required to achieve specification. Tighten the clamp bolt to 24 Nm (17 Ibf.ft).