Torx size for Crank Sensor screw?

[bordonbert]

Hi, newbie to the forum. I have to change the crankshaft position sensor on my 106 Zest3. It's the thin curved plastic moulding which sits on the top edge of the clutch housing at the front of the engine. Should be an easy job other than the access. The locating screw which holds it in place just above its wiring socket is a torx type but from my set, a T25 is too small and a T30 is too big. Is it really something like a T27? If not can anyone tell me what it is? If it is can anyone tell me why?

Then can you tell me is there also a larger allen screw which needs to be removed at the top end of the sensor? I seem to be able to see one up there but I'm not sure if it is part of the assembly.

[davidireland]

It definitely not t27. T30 as far as i remember.

[bordonbert]

Thanks for the response David, that's what I would have imagined.

The T25 is so small that it turns under pressure without even apparently damaging the screw, it is small enough so I wouldn't imagine a T27 would make enough difference. Trouble is I can't get a T30 in for love nor money, it lines up well so isn't too over the top, but it just doesn't even start to go in. The screw looks untouched too, it isn't chewed up in any way. I guess I'll just have to try to tap a T30 home with the "Fitter's Friend".

Can anyone confirm a T30 for certain? Also, is there only the 1 screw to remove to get the sensor unit out?

[bordonbert]

Ok, problem solved. For the record it IS a T30 screw and it is the only one holding the sensor in place. The T30 driver slotted in as soon as I clouted it (lightly) with a hammer. The access is difficult so I was wary of trying this before and a short T30 from a socket set doesn't go in there at all if the holder has any meat to it. I had to use a very slim longish 10mm socket out of a 1/4" set to hold the short T30 head and it worked fine.

Not convinced the sensor is the problem however, both the old and new ones gave identical 450ohm readings. I suppose it could be intermittent though so glad a new one is in.

Thanks for the advice David it gave me just enough determination to go ahead and whack it in.

[davidireland]

Originally Posted by bordonbert

Ok, problem solved. For the record it IS a T30 screw and it is the only one holding the sensor in place. The T30 driver slotted in as soon as I clouted it (lightly) with a hammer. The access is difficult so I was wary of trying this before and a short T30 from a socket set doesn't go in there at all if the holder has any meat to it. I had to use a very slim longish 10mm socket out of a 1/4" set to hold the short T30 head and it worked fine.

Not convinced the sensor is the problem however, both the old and new ones gave identical 450ohm readings. I suppose it could be intermittent though so glad a new one is in.

Thanks for the advice David it gave me just enough determination to go ahead and whack it in.

Whats up with your car?

[bordonbert]

We have a rotten intermittent. The car runs for weeks without missing a beat. It starts first time 2nd or 3rd turn and has never shown any problem while running. Then out of nowhere it will suddenly refuse to start. It isn't always when it is cold or damp, you can turn it off, wait just a few minutes and go back to it and nothing. No amount of cranking will make it go, it turns fine but will not start under any circumstances. It always then seems to need a long random wait before it will restart, not just till it is cold, sometimes a couple of days pass. Of course this never happens when you have the time to diagnose it when it is in a fault situation.

We have changed the ignition coil pack as the old one was coming away from its potting case but no difference. We were advised by a friend to try putting it in gear, turning it on and rocking it to move the flywheel and register a pulse from the sensor. Hard to say, but sometimes this seemed to work but other times no difference. As the crankshaft sensor was so cheap I changed it as a matter of course. As the 2 sensors had the same resistance reading I am now waiting to see if this makes any difference. If you can suggest any other things to try I would welcome it.

I started chasing wiring through based on the Haynes (Heiney?) manual and found some strange things. It is a '98 1.1i Zest3 with a HDZ engine and Bosch single point injection. The way I read it, for my chassis number, (after 50 191 756) with TU1ML/Z engine, the manual shows this should have a Bosch A2.2 injection setup. Mine has an ECU on the right wing which is labelled MA3.1. I think that must have been a "any model will do" exchange before my time. The Haynes only lists other models as having MA3.0 or MP3.1 and mine is clearly labelled MA3.1, is this maybe a typo in the manual as I can't find a reference to a MP3.1 online anywhere? Mind you this is listed in Haynes for the TU3 anyway so is not really relevant.

Another oddity, all of the Haynes schematics show the injection relay as having pins 8 and 15 bridged internally, my relay has this verified with a meter. 8 is fed with permanent live (BB13) while 15 feeds permanent live from the relay to the injection ECU (BB12). In mine the relay is correct, (the internal schematic is moulded on the top and matches the book exactly), but the socket has no pin 15! I mean the tiny clip inside to accept the relay pin is just plain not there. All others show as they should, for example 3 is also missing but is an unused connection on the schematic. Also pin 18 on the ECU shows no sign of a permanent 12V from another source as it should, (according to Haynes). Yet it runs (sometimes).

I'm a bit mystified by the symptoms and what I have found so any ideas and info would be warmly received.

(EDIT: Oops i'm wrong, the MP3.1 ECU does exist. It seems to be for the larger more sporting engines. Anyway, mine is still a MA3.1, clear as day no chance of reading it wrongly. I'll post a pic if it is needed.)

[davidireland]

Post last eight of chassis. i'll send you a wiring diagram.

[bordonbert]

Thanks for the help David. The VIN is HDZE52282174. Should be for a '98 Zest3 as I said.

[davidireland]

Ok. Cannot get a diagram off servicebox as your car is an oldish one. Will have to go to the books.
Just a thing to check. Your car has an inlet manifild heater with a relay that operates it underneath the engine ecu.
Faulty operation of the inlet heater will cause your problem. Thats the first place id check and go from there.

[bordonbert]

Thanks David. I think I know the relay you are talking about, it's alongside the injection relay. I wondered what it was for. I'll look into that in the meantime.