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[magnul]

A few questions from a newbie:

A few days ago I got fault code 92-camshaft sensor incorrect signal, and the car went into limp home mode. I ordered a replacement from ebay and changed it today.

1) The fault persists. EML lights up a few seconds after start, and the engine still has to be cranked longer than usual to fire. Any ways of testing sensor and/or wireing with a DMM? Can incorrect fitting of the timing belt cause cam sensor fault? The timing belt was of a couple of weeks ago when I had the HG replaced.

2) I have never removed the timing belt cover before, and never seen a cam belt. I was a bit surprised that it wasn't fully tensioned all the way around. There was quite some slack on the exhaust side. Is this normal?

3) After replacing the sensor and starting the engine I noticed a funky smell. Like hot (but not burning) rubber or plastic. Is it possible to do anything wrong when refitting the timing belt cover? I also imagine that I hear some noise from that area. I may just be hysteric, but I'm a bit concerned about that part of the engine :-/

The car is a -95 2L 16V

-Magnus-

[TheBoy]

How much slack?  Should have reasonable tension all way round. Do not use if it has more slack than this!

Incorrect timing can cause ecu to think cam sensor problem. When cambelt changed, was the tension also changed, or just the belt? If just the belt, do it again properly, with tensioners and rollers.

[magnul]

Tension didn't appear to be even all way around. Could probably push the belt 1cm without much force on the stretch below the exhaust cam.
Cam belt wasn't changed when HG was changed, since belt, tensioners and rollers were changed a few months ago.

-Magnus-

[magnul]

I just had another look, and I think that the smell is from the exhaust manifold (small experiment with exhaust repair tape on a small crack) and the noise appears to come from the PS pump.

Assuming that timing belt is OK, how do I test the sensor? Will the AC reference signal be on with just ignition on? Is it possible to remove the connector with the engine running?

I think I'll ask the mechanic who did the HG change if the timing belt has excessive slack. Forgot my Haynes manual while on holiday, so I can't really check anything myself.

-Magnus-

[magnul]

Nobody knows how to test the sensor and/or wiring?

Perhaps a dumb question; is it possible that a faulty crankshaft sensor cause discrepancy between cam- and crank signal and hence apparent cam sensor fault? The wiring on my crank sensor is in awful condition.

-Magnus-

[Grumpy]

Nobody knows how to test the sensor and/or wiring?

The only way to check the signal properly is to use an oscilloscope
to check the waveform it produces. Tech 2 boys will know more than
me, but I would imagine you would need to take it to someone
who owns the equipment as the cost of buying would be prohibitive.

As for the wiring, you'll need to identify the connections on the ECU and
do a continuity check between the Cam sensor and the ECU.
You can do this bit yourself with a conventional multimeter. They're
not expensive and worth their weight in Gold for checking out
electrical problems.

Sorry I couldn't be of more help.

[Grumpy]

The wiring on my crank sensor is in awful condition.

Change it now while you can do it at a time and place of your choosing.

It will fail if you leave it.

Not expensive and well within the scope of a 'do-it-yourselfer'.

[TheBoy]

If the wiring continuity is OK, sufficiently away from alternator, the cam timing is correct, then it will be the sensor.  It seems on of the capacitors fails inside the sensor itself...

[magnul]

Thanks. I didn't think of such simple things, as I'm not completely aware of the way the sensor works. I can cope with DC, but hate AC;) I have DMM, so I guess it's just a matter of disconnecting the big connector to the ECU and check continuity from pins 2, 4 and 22* to the plug.
I measured resistances in the old sensor (open circuit) and the new one (20ish ohm between left and right pin and short circuit to middle pin).

I ordered a new crank sensor yesterday and will change it when it arrives next week. Just wondered if it could be related, but obviously best to check the simple stuff first.

*According to: http://www.euroscan.hu/files/sim561.pdf

[magnul]

I've checked the continuity, and it's very good (actually read -0.5ohms, never seen that before).
What's the thing with the modded sensor I've read about? Is the sensor different or just the wiring?

[Grumpy]

I've not heard about an actual modded sensor, although that doesn't
mean there isn't one. Someone here will know.

What is important is the modded route of the wiring. 'Spikes' from the
alternator were damaging the the cam sensor, so the cable routing
was modified to route it away from the alternator and it's cabling.

The cable run from my cam sensor runs past the inlet manifold and
round the back of the cylinder head to join up with the ECU.

Don't know if that helps you?

[holey head]

i believe it is both the sensor and the wiring and connector that have been modded. thats why the new sensors come with a new wiring loom. as grumpy says it's to help protect against "spikes"!!!!! in my opinion get genuine sensor as i bought 2 and neither worked till i bought genuine one.
only bout £45 i can give part number if you want as well!

[magnul]

I guess your car had the modded sensor fittet from factory as yours is newer than mine? The sensor I bought from ebay has Vaux P/N 90458252. Came without new loom. Sensor looks identical to the old one. Do the P/N match the genuine you bought?

[holey head]

no mine had un-modded one fitted.i had to fit modded one. no the part number wrong, the genuine modded one p/n is 93171450

[magnul]

So it's basically a shielding problem then. Find it a bit puzzling, as the problem started as a temperature dependent one (fault only appeared at hot start). Think I should hook it up to a Tech2 and check some livedata before buying any more sensors...