1998 Vectra stalling, MIL light on, but no fault codes in ECU memory

You dont mention if the engine misfires or looses power whilst the tacho is jumping about, rather than just dying, but this definately sounds like the infamous CPS problem.

Tim..

Well, it's hard to say what's really happening, the engine might be still firing, I do see the power dropping, speed falling off.

As you probably know, when the engine dies, PAS dies too, so I have about 10 seconds to get the engine going again before the steering becomes very difficult. Yes, it's possible the engine is still running, but usually, when all of the dash lights are on, the engines stalled. Next time, I'll be able to make a better judgement, I'll just let it coast to a stop (assuming it's safe to do so).

What's the CPS, or is that a typo, should it be TPS?

If it is the TPS, why does it die, then recover when the engine is restarted & go on to work fine until the end of the journey?

Is there some way to fix it?

Gerry

Ok, replying again to myself ;)

Looked on net for CPS = Crankshaft Position Sensor AKA crankshaft sensor, Ok, I got it.

Yeah, I suspected this, was looking at it today, it looks to be a ba$tard to replace, have to take the PAS pump out first, although some web discussion seemed to say you could remove the exhaust heat sheild + dipstick & do it that way. Hmm, there's a few Torx headed bolts, have to buy a set of sockets.

I think you are correct Tim, it must be intermittent. It's strange how they fail, do you know if it's a passive (magnetic pickup) or active (hall effect) sensor?

Actually, this sounds like the exact same problem as on my wife's Hyundai coupe, the crank sensor used to go open circuit when it heated up. Used to work fine when it was cold or had time to cool, but if you stopped the car when it was hot, there was no way to get going again. Hard to believe such as simple failure could disable the car.

I bet the Vectra overheating episode caused it to begin the decent into premature aging. Damned tailbacks.

Guess I'd better buy a replacement

Gerry

Actually no, CPS is camshaft position sensor.

CAS is crank angle sensor.

Both fail with frightening regularity on the ecotecs, although check the CPS first.

Tim..

First, AFAIK you can't read Vauxhall fault codes without a proper fault code reader.

Having done this on my Omega ecotec, if you have aircon then the pump _must_ come off, as the sensor is behind the bracket. You may be able to get a finger to it, but you sure as hell can't undo the bolt. The pump isn't as bad a job as it sounds. The belt comes off quite easily with a

15mm socket on the tensioner, then you have three bolts on the front and four on the back. You should find that a normal 11mm socket will fit them (its a TX60). As regards buying sockets, TX sets are expensive, but you will only need a few sizes (50, 55, perhaps 60), so it's probably cheaper to buy those individually from Halfords. I replaced the rear bolts with normal 13mm head bolts! The pump can then be shifted aside - there's not much room but it can be done. You will then need to unbolt the aircon pump bracket, which IIRC is four 15mm head bolts, one of which is shared with the engine mounting which will also have to be slackened but not removed.

The cam sensor is more of a bitch if you ask me; I've only accessed mine through removing the head, but to do it without would mean removing the cambelt - in itself a doddle on the RWD Omega, but probably worse on the Vectra, and the backplate, which will mean removing the cambelt idlers. Once again, the sensor is attached by a small TX head bolt, but I found a hex socket which fitted.

Is there a simple test I can do, because there are no error codes stored, but I get the them if I turn on the ignition with the engine off?

Was going to purchase a new CAS, but if it might be the CPS, then I'd better be sure to buy the right part.

I can trace the CAS lead to a connector near the top right of the engine bay, but I can't seem to find the CPS connector, it runs down under the fuel injection.

I suppose I can start the engine, pull apart the CAS connector, see if the MIL comes on, or is this a bad adea?

Gerry

Take off the black plastic spark plug cover from the top of the engine, it lives under there.

If you do the engine will stop. No signal from the CAS is one fault the engine won't tolerate.

These sensors can be tested. It depends on the engine as to which sensor is fitted and how it is tested, and there are three variations according to Autodata. If it's an X18E1 or X18XE1, the sensor should read 500-560 ohms between pins 1 & 2 (look at the plug with the single lug to the top, 1&2 are left & centre) If it's an X18XE it's a bit more difficult as there are two types, email me describing the plug.

Likewise for the CPS, the X18XE has two types. For the others, read 0 ohms between 2 & earth, 5v between 3 and earth, and you should connect a LED between 1&2 at the back of the (connected) plug which should flash when the engine is cranked.

Note that both parts can be bought from a good spares shop for about half what Vauxhall will charge, but be careful to get the right one! I speak from bitter experience here... which is why there is a new CAS sitting on the desk next to me which is almost certainly the right one for your car.

Going back to your original post,

All these systems store fault codes in the management computer. If I were you I would get those fault codes read properly by a diagnostic computer, as the troubleshooter in Autodata lists the VAF, MAF and MAP sensors before the CAS and CPS for all the faults that are remotely like yours. Mobile guy near me charges about £35 for the job, you may be able to find one near you. Buying the wrong sensor will cost you that much.

Changed the crank angle sensor tonight, MIL light is still on. Tried resetting the ECU, MIL light still comes on.

The CAS was definitely on the way out, the insulation was frayed & missing from the leads at the point where it enters the sensor body.

However, a replacement does not appear to have fixed the problem.

During the week before I changed the CAS, the time to failure shortened each day, eventually it just failed (I assume) as the MIL came on permanently.

Plan to change the CPS tomorrow night, hope this fixes it for good.

Thing is, if the CAS was faulty, & the CPS was faulty at the same time, I would expect the engine to refuse to start, or else stop (inconveniently) every so often.

If I short ALDL pins 5 & 6, turn on the ignition, I get the flash codes for CAS + CPS + ignition coils, which is what I would expect if the engine is not running.

Get none of these when it does start, except the MIL illuminates after about 1 second.

The engine is definitely rev limited at about 4200.

Gerry

That's common, it gets hot down there.

How can you reset the ECU without diagnostic gear? All the info I have says you have to use a proper fault code reader, I couldn't get anything out of mine without it.

I still think you would be better off getting a proper computer connected to it instead of the guesswork, it will be cheaper in the long run.

Went to change the camshaft sensor tonight, using the procedure from the following site (appears to be offline ATM)

Took a bit more effort, my Vectra has 2 pipes running between the air filter box & the cambelt cover.Not sure if they are Air-con or PAS. Got the cambelt cover off, the belt seems slack. I remember someone posting previously that a slack cambelt can cause the MIL to illuminate.

I'm now concerned the belt has jumped a few teeth & the timing is out, causing the MIL to light up & the revs to be limited. With the cambelt cover off, the section of belt on the right is not really pressing against the roller with any great amount of tension. I can rotate the roller on the right side easily with just finger pressure, where as the one on the left is tensioned too tightly.

Is there some way to check the tensioner is set correctly?

The cambelt + rollers + water pump were all changed about 22K miles ago. Not sure if the tensioner was changed, I could go & ask.

I suppose I can go ahead & change the CAS sensor anyway, but I suspect htis won't fix the problem. Is it easy to check whether the belt has slipped?

Gerry

Ask in the forums at

there are some very knowledgabale people in there who know their Vauxhalls inside out - they've helped me a lot with my Omega. I was suspecting the TPS sensor on mine, but advice from those in the know for my uneven idling is to clean the throttle body!

Just above the crank pulley is the tensioner, which is set with an Allen key, and it has a pointer to indicate where it should be set. However I understand it's important to replace the tensioner assembly when the belt is changed.

my guess would be to get the slack sorted first, I would also surmise that 'if' the teeth had jump, you should be getting some additional problems as well, rather than just limited revs.

I'd go ask if the tensioners were changed if you can confirm this, if not change them and then restart your diagnostics,

slack will cause the cambelt sensor to give erratic readings.

mike

Job Done!! Was the camshaft sensor all the time, replacement cured it.

Chris, took your advice & signed up to

Loads of good info there.

mikeFNB, found a "how to" on cavweb, cambelt change.I read through this & found a section dealing with belt tension. My cambelt seems tensioned ok.

Chris, I manually lined up the timing points on the sprockets, all were in alignment, so no problem there. Also, checked with the guy who did the cambelt last time, the tensioner was changed, so no worries about it failing (touch wood).

So, everything back to normal again.

With regard to the ECU & failure codes, although my Vectra has an ECU that will flash fault codes (paper clip trick), it does not seem to do this when the engine is running. It will flash when the ignition is on, but the engine off. However, that's of limited use.

Only people with Tech 2's in my area are main dealers, they have long queues (2 week wait for testing is normal), so I won't be going near them anytime soon. I believe the ECU will reset the stored faults after

25~30 starts (or if I feel like it, I can switch the ignition on/off that many times).

The MIL is off, will do a proper run tomorrow, see if I can get above

4200 REVS.

Thanks for the help

Gerry