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Discussion Starter #1
Hi folks,

Just wanted to give everyone who is/has/had or will be changing the timing belt to check the condition of the exhaust cam sensor ring and its clearance to the position sensor!

Take special care when removing the exhaust cam with a cam tool lever, as to not make contact with the sensor ring as it is easy to bend and distort.

Isn't it wonderful being a owner of a second-hand car that has been worked on by careless and lazy mechanics...

My GTV experienced a sudden and complete engine halt on the road, lucky near home and in a spot down hill where i could roll to a unlimited parking spot. She held out till the best moment i guess.

After going through the typical "engine no start" diagnosis, i tested the camshaft position sensor/switch and it failed. On further inspection after removal of the exhaust cam gear and the sensor itself i could see that the sensor ring on the gear had been bent and was rubbing on the hall effect side of the device.

Breakdown to likely cause of failure:

1. Dodgy and lazy mechanic failed to take care when installing or removing the cam gear during timing belt replacement.. I suppose this is in character as he decided to also use gasket sealant on the camcover and the EGR port! Far out man! like the gasket costs a song to buy new! and for F*&^k sake you couldn't find an o-ring for the ERG port????

2. The now bent sensor ring starts rubbing on the camshaft sensor housing and the engine runs... for now.

3. After some time the plastic housing has rubbed clear and the sensor ceramic substrate is exposed, the metal on the sensor ring has been abraded off so (see attached image), i imagine there is little contact now, but perhaps varying friction based on temperature

4. New owner takes the car for a free way drive, and the additional friction causes the sensor temp to increase and seal the fate of the camshaft position sensor.

Anyhow if hope this prevents other GTV owners from having to buy and replace a camshaft sensor with its life cut short.

Cheers.
 

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Yap, in my case straight after engine swap it wouldn't start because of that damn fragile sensor. Guys at the service workshop had to work overtime.
 

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Discussion Starter #3
DIscovered that I could of replaced just the hall effect sensor by itself for a fraction of the price, with some plug changes! (Jaycar part zd1900 $25AUD) The specs on their website are incorrect and the device datasheet (HKZ-101) shows that it should be compatible . Think I'll do this just for fun aswell. Looks like it could be more durable than the OEM part too.

If it all comes together well I'll put up a post with details and send my prototype to any willing alfa owner.

What do you guys think?
 

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DIscovered that I could of replaced just the hall effect sensor by itself for a fraction of the price, with some plug changes! (Jaycar part zd1900 $25AUD) The specs on their website are incorrect and the device datasheet (HKZ-101) shows that it should be compatible . Think I'll do this just for fun aswell. Looks like it could be more durable than the OEM part too.

If it all comes together well I'll put up a post with details and send my prototype to any willing alfa owner.

What do you guys think?
Mine is now from 146 I believe.
 

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The specs on their website are incorrect and the device datasheet (HKZ-101) shows that it should be compatible .
Fantastic bit of info. Googling the number shows some alternatives -

SIEMENS HKZ101 HKZ101E HKZ101S HKZ121

VOLVO 1346792-3

Hüco 138152

FACET 8.2722

BREMI 16522

INTERMOTOR 14011

as it is used by various other manufacturers.

The connector is a Junior Power Timer ( although probably difficult to find in blue ) which uses the same named crimp terminals. Full kits ( connector, crimps and wire seals ) available from places like Aliexpress.
 

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Discussion Starter #6
Well as it turns out my ebay replacement from micksgarage_australia is cactus!, unfortunately for me i didn't test it before installation. Discovered that only after hooking up a automotive scope i noticed the waveform from the sensor looking irregular. Engine didn't start up initially, but after disconnecting the ECU and reconnecting it, the engine did turn. It looks like the signal was acceptable enough for the ECU to determine ignition, but after the sensor failing it appears it has gone into some kind of limp mode.. I didn't think this was possible with the motronic M2.10.4 units! I know this is the case because while i was doing some testing on the car to check the compatibility of the HKZ-101 hall effect sensor, the engine started WITHOUT the cam position sensor connected!! WTF??

So it would seem that the ECU keeps a record of the last know timing signal position in relation to the crank sensor and must use this as redundancy. Which explains all the "strange" idle behavior ive been getting since the installation of my "New" sensor. I'm kicking myself for not bench testing it before installation - a "trust-no-one" approach would of saved me heaps of frustration in this case!

So it looks like ill be rebuilding my cam position sensor as my working replacement after all.

Ill make an effort to document this and post a detailed how-to so others can use this as an alternative. I paid $75AUD plus $30 for express shipping to my dodgy ebay seller, and this sensor can sell for $290AUD to $60 from my last search on the net. So i guess a $25 + fittings and time, could be an attractive solution for some. Plus don't forget the intimate knowledge of this sensor and ECU function that you will gain from going through this exercise... trying to see the glass half full here as you might guess. But still ****ed off at getting "had" by ebay..

Time for a beer i guess.
 

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I know this is the case because while i was doing some testing on the car to check the compatibility of the HKZ-101 hall effect sensor, the engine started WITHOUT the cam position sensor connected!! WTF??
That's normal. You'll get a check engine light with a faulty cam phase sensor, but the engine will run. I recall reading somewhere that it then uses the crank sensor and has to learn where the engine is in the cycle ( but it won't run optimally ).
 

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Discussion Starter #8
hummm, interesting. I haven't had a check engine light present, and come to think about it.. like NEVER. I smell a rat, maybe my instrument cluster has been tampered with.??.. Wouldn't surprise me as the km's were too good to be true. But i never pay any attention to the "displayed" odometer value anyhow and look at the car it self to tell me the truth..

Thanks for the info.
 

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Yup, tested the signal for "Check Engine light" at the ECU and its present, but not lighting up the LED on the instrument cluster. Seems as though the wire could be intentionally cut to hide this! mother *******s!

Well at least now i know.
 

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Discussion Starter #10
*An update*

I've been running my alfa with my "rebuilt" cam position sensor for a while now, and its running much smoother as expected. Took many photos while doing this repair so i can complete my "how-to" doc to post. So far I am pleased at the ease of this repair and its reward. So i do hope that it would benefit other owners out there when i finish writing it.

Attached is a scope capture of the installed sensor signal with the crank sensor and it nice square wave output..
..wish i got a capture of my dud sensor so everyone can see the difference lol
 

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