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964/993 Hall Sensor Supplier Needed

My 1991 964 is broken down with a defective Hall Sensor in my twin plug distributor. I have tried unsuccessfuly to find a supplier that can repair the hall sensor in my distributor or a supplier that is able to sell me the hall sensor. I have checked with various Bosch Services but was not successful.
Would be great is somebody could provide me with an address.
Thanks
Old 11-15-2008, 05:53 PM
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Where are you located? I have a spare used on still in the assembly you are welcomed to it, gratis Just cover shipping.

Old 11-17-2008, 02:45 PM
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Hall sensor needed

Thank you very much. I greatly appreciate the help. I am living in Auburn Hills, Michigan, 48326. Please let me know your address and the shipping cost and I will send you a check today.

My email is smhorneck@comcast.net.
Old 11-17-2008, 07:17 PM
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Hi,

I am currently having trouble with a 91 C4, it stalled while driving and wonät start now. It sort of tries to start, and after fiddling with it and doing a basic tuneup, it sometimes starts with great hesitation and idles real lumpy at 600 rpms. If I touch the throttle pedal, it dies.

The engine trouble codes were read with a bosch "hammer" and initially there were two codes: one for the Hall sensor and one for a "control unit" which after surfing online seems to point towards the knock sensors...?

I wonder what led you to believe your Hall sensor is defective?

Anyway, I too learned that it is hard to find Hall sensors separate, you'd need to buy the whole distributor. However, after several more hours of fiddling, I discovered that if I pull the multi-pin connector from the coil that sits closer to the firewall, the engine starts up and runs fine!!

This leads me to believe that the Hall sensor is not defective on my car, despite the error code. (The slave distributor doesn't even have a hall).

I am not done troubleshooting, I just thought you might want to try disabling one coil/distributor like I did, and see if you get the same result.

This one has me stumped, I thought I was pretty good with this stuff

Oh I also replaced the flat black transistor/whatever component that the multi-pin connector connects to. No effect.

I pulled all lower plug wires off the distributor cap to eliminate the possibility of crossfire or incorrect timing on the lower plugs. No effect.

Jan
Orlando, FL
Old 11-18-2008, 07:44 PM
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I could be completely wrong but did you check you distributer belt recently? If you unplug one of your coils and the engine runs fine, is it possible your secondary distributor is not working correctly? Just a guess .
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Old 11-20-2008, 12:51 PM
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Jan,

A missing or defect hall sensor alone doesn't cause much trouble. It results in the DME retarding timing for all cylinders since it doesn't know which caused the ping. It won't throw up a CEL but will give you a fault code "1_34 Hall Signal" on the Hammer. I had this condition for a long time and didn't even notice it until I hooked up the hammer one day.

The fault code "1_33 Control unit" means that the knock computer (second MCU in the DME) is bad and ignition is retarded by 6 degrees. You need a new DME to fix this one.

The fault code "1_41 Control unit faulty" indicates that the checksum of the EPROM in your DME is incorrect - most likely because you have an aftermarket chip installed. Again, by itself it should not cause what you observe. This error will throw up the CEL (if installed) but not cause any additional issues. If you are sure you have the original chip and still get that error than you have a bad EPROM. While these have a data retention of more than 20 years they can start to loose their stored information. I simple replacment with another stock chip and you are good to go.

If your car doesn't idle properly I would check if both coils fire. To do that simply unplug one of the ignitors (black box in front of the coils) at a time and try to start. The car should start with one of them unplugged. If not you could have a snapped belt in your distributor.

Next on the list are vacuum leaks, fuel pressure regulator, O2-sensor, AFM connector. All these if not working properly would cause poor idle.

Cheers,
Ingo
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How about a NoBadDays DualChip for 964 or '95 993
Old 11-20-2008, 03:30 PM
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Thank you guys for your replies.

The belt must be ok since the slave rotor turns with the master and both are pointed at the #1 mark at the same time.



>A missing or defect hall sensor alone doesn't cause much trouble. It results in the
>DME retarding timing for all cylinders since it doesn't know which caused the
>ping. It won't throw up a CEL but will give you a fault code "1_34 Hall Signal" on
>the Hammer. I had this condition for a long time and didn't even notice it until I
>hooked up the hammer one day.


well I eliminated this possibility by swapping out the distributor, took it from a running car. No change.


>The fault code "1_33 Control unit" means that the knock computer (second MCU
>in the DME) is bad and ignition is retarded by 6 degrees. You need a new DME to
>fix this one.

Swapped out the control box under the driver's seat, used another one from a running car.. no change.
Even 6 degrees retarded, it should still run and respond to throttle. This one doesn't tolerate any throttle at all. It sounds like it's firing on 3, then missing the next 3, then firing on 3 again, then missing 3.... very lumpy.



>The fault code "1_41 Control unit faulty" indicates that the checksum of the
>EPROM in your DME is incorrect - most likely because you have an aftermarket
>chip installed. Again, by itself it should not cause what you observe. This error
>will throw up the CEL (if installed) but not cause any additional issues. If you are
>sure you have the original chip and still get that error than you have a bad
>EPROM. While these have a data retention of more than 20 years they can start
>to loose their stored information. I simple replacment with another stock chip and
>you are good to go.

As above, another main unit did not fix the problem.

>If your car doesn't idle properly I would check if both coils fire. To do that simply
>unplug one of the ignitors (black box in front of the coils) at a time and try to
>start. The car should start with one of them unplugged. If not you could have a
>snapped belt in your distributor.

The car indeed starts with one ignitor disconnected, seems to run fine with just one coil, the one closer to the rear of the car. I unplugged the coil closer to the firewall. This looks like it would be running the lower sparkplugs.

What does that mean? How can connecting the second coil make the car NOT run, while it runs ok with just one coil? I get no backfiring or exhaust popping at all, just feels like something is preventing it from firing except for a few runaway sparks every revolution. Rotor and cap are new on both distributors.

Even if I have no high voltage leads going to the "disabled" distributor, the same problem persists until I also disconnect the ignitor wires from near the coil.

I could maybe try replacing the coil?? Maybe it's internally shorted and is messing up the whole system?

I replaced the black ignitor on the unplugged coil and plugged it in again, still won't run. So it's not the ignitor. What else is there in the circuit that could go bad or short, and prevent the engine from running? The best I can get it to do is very rough idle at 600rpms. So there's SOME fire in the hole, but it won't tolerate any throttle, it would just die instantly. During that bad idle, the air flow meter door flops around open/closed and the intake air bypass solenoid clicks repeatedly. If I pinch off the idle air bypass hose, the engine dies instantly, which is normal I think.

The Idle switch works, as does the WOT switch.


>Next on the list are vacuum leaks,

Can't find any

> fuel pressure regulator,

I get 4bar of pressure. Spec says 3.8 or thereabouts, so that's pretty much in the ballpark. Besides, it runs GREAT with just one coil, so I doubt it´'s fuel related or a vacuum leak.


> O2-sensor, AFM connector. All these if not working properly would cause poor
>idle.

Again, it starts, idles and responds to throttle just perfect, if I unplug one particular coil.


Sorry for the long story. Hopefully this will one day help someone else, it's a real head scratcher.

Thanks again for your suggestions.

Jan
Old 11-20-2008, 07:43 PM
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Jan, do I understand correctly that the car runs better with one of two spark trees disabled. In other words once you disconnect one particular ignitor the car runs and idles but with both connected you have issues?

If that is the case this sounds like you have bad spark plug wires. The 964 DME is VERY sensitive to any sort of electromagnetic interference. A bad leaking spark plug wire (or coil) can disable the Motronic like you see and cause all sorts of issues. The electric noise causes the DME to frequently reset and that is why you get these funny 3 sparks 3 nothing patterns. And a DME reset also causes the resonance flap to actuate.

Have an assistant try to start the car in the dark while you watch the engine. Make sure yours eyes adapt to the dark. If you see some arcing in the engine bay you found your issue. If that doesn't work disconnect (one at a time) the high-volage wires at the cap that causes the issue. That way you can isolate which wire is causing the issue.

If none of the above helps I bet your coil is bad (insulation between the HV side and the low voltage side). Swap it and you should be fine. Also check the ground wires of the DME harness. I think there is one ground point close to the coils. Make sure everything is nice and clean.

Cheers,
Ingo
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I repair/rebuild Bosch CDI Boxes and Porsche Motronic DMEs
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How about a NoBadDays DualChip for 964 or '95 993

Last edited by ischmitz; 11-20-2008 at 08:43 PM..
Old 11-20-2008, 08:39 PM
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Had the bad plug wires blow my DME on my '90 years ago. Had it rebuilt and it came back with a strongly worded note: "Change your plug wires before you start it up with this unit in place." Talked to the rebuilder previously and he asserted the wires caused the unit to fry. Sounds like you are half way there to a real problem. Change the wires.
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Old 11-21-2008, 05:15 AM
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>Jan, do I understand correctly that the car runs better with one of two
>spark trees disabled. In other words once you disconnect one particular ignitor
>the car runs and idles but with both connected you have issues?

That's it.

>If that is the case this sounds like you have bad spark plug wires. The 964 DME
>is VERY sensitive to any sort of electromagnetic interference. A bad leaking spark
>plug wire (or coil) can disable the Motronic like you see and cause all sorts of
>issues. The electric noise causes the DME to frequently reset and that is why
>you get these funny 3 sparks 3 nothing patterns. And a DME reset also causes
>the resonance flap to actuate.


I pulled first the coil high voltage wire from the distributor cap, but it had no effect. I then pulled ALL plug wires from the same cap, still no effect, it still barely idled.


>Have an assistant try to start the car in the dark while you watch the engine.
>Make sure yours eyes adapt to the dark. If you see some arcing in the engine
>bay you found your issue.

I'll do that, thanks.


>If that doesn't work disconnect (one at a time) the high-volage wires at the cap
>that causes the issue. That way you can isolate which wire is causing the issue.

Has to be something else, since I did that already and saw no change.


>If none of the above helps I bet your coil is bad (insulation between the HV side
>and the low voltage side). Swap it and you should be fine.

I'll do that next.

I have a running donor car until maybe Thursday next week.
Of course, if I break something on that, I'm screwed

>Also check the ground wires of the DME harness. I think there is one ground
>point close to the coils. Make sure everything is nice and clean.


Ok, will do.

Jan
Old 11-21-2008, 07:34 PM
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Swap the coil pack from the good running car into yours and see if that makes a difference. Should only take 30 minutes
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How about a NoBadDays DualChip for 964 or '95 993
Old 11-21-2008, 10:01 PM
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Hall Sensor Problems

Jan,

my car has very similar problems as your car. My engine didn't run properly and the Durametric software indicated me a hall sensor problem. I thought that the problem must be related to the wiring and disconnected and tried to clean the pins from the hall sensor and the DME. I also measure the connection between the hall sensor and the DME and found out that the ground cable from the distributor was grounded to the car but the ground didn't arrive at the correct pin of the DME.
After all attempts from me to fix the car the problem has gotten worse. The engine has no idle anymore and stops firing every couple of seconds when I drop below 2500 rpm. I can only keep the car going by reving it up to 6K the slip the clutch, drive a few yards and then the engine dies. I can restart the engine right after that again.
I have to admit that I am at the end of my knowledge and have dragged the car to a Bosch service that told me I need a new hall sensor. The Bosch service has no other better idea.
Reading all comments I am sure the hall sensor is not my only problem.
Any idea what can cause my engine to stall below 2500 rmp?
I have changed all my spark plug wires and the car was running fine after that. My problems have started as I tried to work the connectors of the DME and the hall sensor on the distributor. I have used WD 40 to improve the connection. Might this have caused a problem?
Any recommendation of a company in the Detroit aera that might be able to fix my electrical problems?
Old 11-22-2008, 06:01 PM
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Jaggi,

your symptoms do sound like they could be a result of a bad Hall sensor.

have you noticed if there is a difference between a cold engine and a fully warmed up engine? Sometimes heat expansion affects Hall sensors that are going bad.

Jan
Old 11-23-2008, 09:25 AM
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As said before: a bad or missing hall sensor doesn't cause problems you describe. I ran my 3.6 engine that way for more than 3 month without even knowing something was wrong. I only found out about it when I hooked up the Hammer one day.....
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How about a NoBadDays DualChip for 964 or '95 993
Old 11-23-2008, 05:57 PM
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Engine Problems

If my hall sensor is not the problem what is cutting out my engine ? I never had a problem like that before that the car has no idle and also is cutting out when I rev it up.
Any ideas what to check next? The problems have started after I worked on the hall sensor connector on the distributor and also on the connector to the control unit under the seat. I have sprayed WD40 into the connectors. Can this have anything to do with the problem.
As the engine cut out while running at 2.500 and higher all control lights n my instruments started to flash. I hope my control unit is OK. Any way to check the DME? I get no failure code with my Durametric tool for the DME.
Thanks for your feedback.
Old 11-24-2008, 06:09 PM
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Jaggi,

Is is difficult to keep track of what is going on here. There seem to be two different guys reporting their problems. So excuse me if I address the wrong guy:

What you report sounds like the DME might be re-setting periodically. This can be caused by excessive electromagnetic interference or poor power supply. Have you checked and eliminnated the DME relay? Next you need to check your GND points. Then check the spark plug wires.

Why are you using WD-40? WD-40 is a highly volatile penetrating oil mixture designed to clean and coat metal parts. It is certainly not designed for any sort of contact cleaning or electrical applications. There are products that can be used to clean electrical contacts. Do a search on Google.

Ingo
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I repair/rebuild Bosch CDI Boxes and Porsche Motronic DMEs
Porsche "Hammer" or Porsche PST2 - I can help!!
How about a NoBadDays DualChip for 964 or '95 993
Old 11-24-2008, 07:52 PM
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Cutting out 964

We had similar problem ran better with 1 ign disconnected and cutt out sometimes..i replace both ign modules and coils..seems that bad coil will send secondary voltage thru primary wiring and will reboot dme.cutting out engine till restarted...both looked and checked fine but problem solved.. Eventually problem will unsolder dme!!
Old 11-25-2008, 07:59 AM
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Engine is ctting out

Thanks for your feedback. After I had changed the spark plug wiring of my car I realized at night that sparks between one coil and the spark plug wiring going the the distributor are visible. Can this cause my DME to reset? Is there a way to check it the DME is damaged?
Old 11-25-2008, 06:03 PM
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Engine Problems

I forgot to ask what the GMD points are and how I can check these and where I can find and check the DME relay. How can I check if my DME has poor power supply and how can I check the ignition modules and the coils?
Thanks for your help
Old 11-25-2008, 06:13 PM
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Quote:
Originally Posted by Jaggi View Post
Thanks for your feedback. After I had changed the spark plug wiring of my car I realized at night that sparks between one coil and the spark plug wiring going the the distributor are visible. Can this cause my DME to reset? Is there a way to check it the DME is damaged?
YES - leaking spark plug wires will cause the DME to reset. Fix this issue before trying anything else. As others said prolonged exposure of the DME to these conditions can lead to permanent damage. Get new wires.

Cheers,
Ingo
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'74 Targa 3.6 (not stock ) - '01 C4 (almost stock) - '00 ML430 (stock)

I repair/rebuild Bosch CDI Boxes and Porsche Motronic DMEs
Porsche "Hammer" or Porsche PST2 - I can help!!
How about a NoBadDays DualChip for 964 or '95 993
Old 11-25-2008, 06:23 PM
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Old 11-25-2008, 06:23 PM
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