How do i replace the hall sensor?

[Eric_Oz_S2]

I want to replace the hall sensor on my S2 as it is faulty.

There are 2 x 4mm allen key bolts attaching it to the back of the cam pully drive gear cover. There is only about 5mm between the bolt and the corner of the cam cover. How are you supposed to remove these bolts without removing the belts and pully. It is so close, but I just can't get an allen key to sit in the bolts.

arghhhhhhhh......

[bazar01]

I am planning on replacing the rear cam pulley cover and change the hall sensor at the same time. The cover is magnesium and is already disintegrating to a point some threaded holes are stripped already. This would mean replacing all the belts at the same time so I'll just wait to do all of them same time.
Is your car down due to a bad hall sensor which I don't think it is? If not, just drive it until it's due for timing belt replacement to replace the hall sensor at the same time.
You can try removing the 2 bolts that hold it in place and go from there. If it does not want to come out, then you have to remove the timing and balance belts and rotor to access the rear cover. Make sure you mark the rotor position before you take it out or your timing will be off.

[Eric_Oz_S2]

The car runs, but is down about 15 bhp. This reduces the 0-62 performance to 7.5s. I don't really want to have to take the camshaft pully off, as then I will have to remove the belts as well and re-tension etc (I don't have a tensioning checking tool). I also don't want to wait for a belt change - I only drive the car on the track so 15hp makes all the difference.

I might try and cut down an allen key so I can manouvre it into the bolt heads.

[bazar01]

The allen cap screw is too close to the head, there is just not enough space to get it out in my opinion.
Here are some pics of the rear cam pulley cover where the hall sensor is mounted.
You may need to pull the rear cover off to get to it.

[Eric_Oz_S2]

Maybe if I remove the cam cover I could get enough clearance?

Have you checked the condition of the hall sensor by removing it from the rear cover? I would be interested to know if the plastic components inside have disintegrated or the wires have frayed/disconnected

[bazar01]

You maybe right about taking off the camshaft/valve cover to get more space for the allen key. I don't have the car with me so I can't confirm that.
I am replacing the hall sensor because of the brittle plug. It just disintegrated with age and the exposure to engine heat. The magnesium cover is also disintegrating esp the threaded holes that's why I am replacing it. The hall sensor itself is robust. Did you check the output signal with a scope or resistance check it with a digital meter?

[bazar01]

Originally Posted by Eric_Oz_S2

I don't really want to have to take the camshaft pully off, as then I will have to remove the belts as well and re-tension etc (I don't have a tensioning checking tool). I also don't want to wait for a belt change - I only drive the car on the track so 15hp makes all the difference.

I might try and cut down an allen key so I can manouvre it into the bolt heads.

I don't have a tensioning tool. I just relied on the spring tensioner but I make sure I warm up the engine a little (not to operating temp) to retension the belt, because if I don't, the tension is too tight and the belt whines when I release the tensioner initially on a cold engine. The car has gone through 4 belt changes already without the belt tensioning tool.

[Eric_Oz_S2]

My plug is also disintegrating. I'm confident there is something retarding ignition, as when I disconnect the sensor there is no reduction in performance (checked using Dynolicious). I've heard these sensors are a problem on the 928's (944's use the same part) and there is a significant performance penalty if it is faulty.

[jannieh2]

The hall sensor isn't critical to the running of the engine but without it the engine will default to 6 degrees of advance rather than optimal timing. No need to remove any belts or pulleys. Only the camshaft cover which leaves better access to the 2 allen bolts. The cheap, shiny-metal allen keys are quite malleable and with a propane torch you can shape them as needed after cutting short the "L" to about 1/4" or less. Then you will have a positive grip on the bolts. Make sure your newly-created tool is fully seated in the bolt before you apply force. This should remove the bolt. When re-installing use a screwdriver, not an allen key. At tools-are-us you can buy a set of extra-long skinny screwdrivers for a few dollars. Use one that fits snugly into the bolt and then tighten. A hideous amount of torque is not needed to hold the sensor in place so the screwdriver will be adequate to facillitate re-installation and future removal of the bolt. Re-install the camshaft cover with a thin coating of Hylomar on both the head and the rubber gasket and you will have no leaks. Watch the torque on the camshaft cover bolts. They can cost $20-30 each from the dealer and can snap off in the head above 8nm. A scope will be able to show that the variable ignition timing has been restored rather than the default 6 degrees and full engine power will return. Hope this is helpful. John

[Panzer909]

I know this thread is older, but my Hall sensor just crumbled apart as well, and now I'm dealing with a really crappy idle & backfire under extreme load. COuld this be connected?

[Eric_Oz_S2]

The idle could be related, but the backfire wouldn't be caused by the retarded ignition.

[bazar01]

my idle was fine when the hall sensor was disconnected.
backfire could be caused by a leak in the exhaust allowing air to mix with unburned fuel in the cat.
check and clean your IACV for idle issue.

[Panzer909]

Hmm. Okay. Did a search on finding and cleaning the IACV for a 16v car and couldn't find anything. Anyone ever do this with some positive results?

[kolll]

Originally Posted by jannieh2

The hall sensor isn't critical to the running of the engine but without it the engine will default to 6 degrees of advance rather than optimal timing.

hi!
I know, that's an oooold topic but , will car run ''normal'' if the sensor is broken? I mean physically broken and stuck in the ring behind the cam gear
what is the part number for this ring?

[djnolan]

My hall sensor plug crumbled. I pushed the terminals into the harness plug and dabbed some liquid electrical tape around everything. The sensor itself seems like it is ok, just the connector was damaged.

That spot gets pretty hot since the exhaust, heater coolant pipe and head are all nearby so the plastic plug won't last forever but the sensor itself is in the distributor and doesn't get as hot, and seems fine.