964 DME fault code - help needed
06-26-2003, 04:16 PM
#1
Instructor
Thread Starter
964 DME fault code - help needed
First of all my engine is running fine from what I can tell. When I flash out my DME fault memory I get a 1-1-3-4 fault. According to the factory WS manual this is the hall sensor at the dual dizzy. My questions are:
1. Does this error get deleted when I disconnect the DME from B+ or could it be something from way earlier?
2. What is this signal needed for in the grand scheme of the DME engine management? Is it to decode the 720 degrees vs. 360 degrees of the flywheel sensor? But then why does the DME need to know?
3. What happenes if the hall sensor is bad? Would the engine still run at all? Is there some sort of emergency program in the DME that does something funny or potentially damaging when running with a broken hall sensor?
4. The factory WS manual simply says: "replace when bad". Where do I get a replacement part. PET does not show anyhting. Please don't tell me I have to spring for a replacement dual dizzy.
Thanks,
Ingo
1. Does this error get deleted when I disconnect the DME from B+ or could it be something from way earlier?
2. What is this signal needed for in the grand scheme of the DME engine management? Is it to decode the 720 degrees vs. 360 degrees of the flywheel sensor? But then why does the DME need to know?
3. What happenes if the hall sensor is bad? Would the engine still run at all? Is there some sort of emergency program in the DME that does something funny or potentially damaging when running with a broken hall sensor?
4. The factory WS manual simply says: "replace when bad". Where do I get a replacement part. PET does not show anyhting. Please don't tell me I have to spring for a replacement dual dizzy.
Thanks,
Ingo
06-26-2003, 04:43 PM
#2
The hall sensor fault code often comes up, even with the hammer (Bosch tester). It doesn't mean the sensor is faulty, other components can trigger that fault code.
Unless you have the system diagnosed with the Bosch tester and confirm the actual fault, replacing the hall sensor won't necessarily fix the problem. Never replace parts without confirming the actual fault.
Unless you have the system diagnosed with the Bosch tester and confirm the actual fault, replacing the hall sensor won't necessarily fix the problem. Never replace parts without confirming the actual fault.
06-27-2003, 02:52 AM
#4
Ingo:
I have a write up on my site (see below my signature for the link) about using the diagnostics.
As far as your problem goes, I would first do as "wrencher" suggested and reset the DME to see if it comes back on. If it does, then you likely have some type of problem, if not it may have just been a signal that the system picked up erroneously.
In the event that the problem does re-occur after a DME reset, I would first look at cables and connections rather than assume the sensor is bad. The faults indicated by the DME mean that a fault is detected in the signal path between the DME and the sensor, and this includes not only the sensor but the cables and connectors as well.
As far as to why the car seems to be running OK, it's in "limp home" mode. This mode is HARDLY limp, but the DME is just ignoring as many sensors as possible instead of running in an optimized, high-performance mode.
Hope this helps,
<img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />
I have a write up on my site (see below my signature for the link) about using the diagnostics.
As far as your problem goes, I would first do as "wrencher" suggested and reset the DME to see if it comes back on. If it does, then you likely have some type of problem, if not it may have just been a signal that the system picked up erroneously.
In the event that the problem does re-occur after a DME reset, I would first look at cables and connections rather than assume the sensor is bad. The faults indicated by the DME mean that a fault is detected in the signal path between the DME and the sensor, and this includes not only the sensor but the cables and connectors as well.
As far as to why the car seems to be running OK, it's in "limp home" mode. This mode is HARDLY limp, but the DME is just ignoring as many sensors as possible instead of running in an optimized, high-performance mode.
Hope this helps,
<img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />
06-27-2003, 03:04 AM
#5
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Dear Ingo,
If the hall sensor has failed and I do not believe this for a moment that it has you have to replace the whole distributor assembly.
In your post you neglect to give some important information. Model year of your 964 and the version of 964. That is ROW (rest of the world) or USA. This infomration is critical in answering your questions. Many owners have hooked up the check engine light system DIY. However it does not always work correctly depending upon the part number of DME installed. Most of the time this particular indicated fault turns out to be the result of trying to use the check engine light with the wrong DME.
Ciao,
Adrian
911C4
If the hall sensor has failed and I do not believe this for a moment that it has you have to replace the whole distributor assembly.
In your post you neglect to give some important information. Model year of your 964 and the version of 964. That is ROW (rest of the world) or USA. This infomration is critical in answering your questions. Many owners have hooked up the check engine light system DIY. However it does not always work correctly depending upon the part number of DME installed. Most of the time this particular indicated fault turns out to be the result of trying to use the check engine light with the wrong DME.
Ciao,
Adrian
911C4
06-27-2003, 02:28 PM
#6
Instructor
Thread Starter
Adrian,
good point. I think the early 3.6 DME's had 911.618.124.00 or 02. Those did not have the check engine light function. In ROW the check engine light was not wired in from stock. Still the DME's had the function, if I am not wrong.
My engine is a 91. My DME is part is #964.618.124.03 Even though it came from Europe both PET and the factory WS manual identify the DME as the one used for US spec cars from 92- amongst others.
The check engine light works fine in all other respects. It comes on during starting the engine and goes off about 5 seconds after the engine start. If I switch over to a custom-made RUF chip it stays on.
Flashing out fault codes by depressing the accelerator works and gives the fault code.
Do you know what the hall sensor is needed for?
ingo
good point. I think the early 3.6 DME's had 911.618.124.00 or 02. Those did not have the check engine light function. In ROW the check engine light was not wired in from stock. Still the DME's had the function, if I am not wrong.
My engine is a 91. My DME is part is #964.618.124.03 Even though it came from Europe both PET and the factory WS manual identify the DME as the one used for US spec cars from 92- amongst others.
The check engine light works fine in all other respects. It comes on during starting the engine and goes off about 5 seconds after the engine start. If I switch over to a custom-made RUF chip it stays on.
Flashing out fault codes by depressing the accelerator works and gives the fault code.
Do you know what the hall sensor is needed for?
ingo
06-28-2003, 03:32 AM
#7
A 3.6 in a'74? Did I mis-read the car type?
Hardly your typical 964 to evaluate with a CEL.
Real 964s are bad enough with random CELs because
of electrical RF noise.
Where did this engine come from, U.S. or ROW,
or who knows? With your '74, why would you care
about the CEL?
Loren
'88 3.2
Hardly your typical 964 to evaluate with a CEL.
Real 964s are bad enough with random CELs because
of electrical RF noise.
Where did this engine come from, U.S. or ROW,
or who knows? With your '74, why would you care
about the CEL?
Loren
'88 3.2
Trending Topics
06-28-2003, 04:39 AM
#8
Additional Post:
I can't believe you guys are providing all
sorts of "answers/fixes", when who knows
what kind of installation was made with
this 3.6 in an old '74.
The grounding and shielding of all the DME wiring
is very critcal on 964 DME. The 3.2 DME is
less critical/not at all. Try focusing how
the installation was done. I've seen a lot
of crude installations over the last 15 years
working with Porsches.
Don't throw darts at the problem!
Good Luck
Loren
'88 3.2
I can't believe you guys are providing all
sorts of "answers/fixes", when who knows
what kind of installation was made with
this 3.6 in an old '74.
The grounding and shielding of all the DME wiring
is very critcal on 964 DME. The 3.2 DME is
less critical/not at all. Try focusing how
the installation was done. I've seen a lot
of crude installations over the last 15 years
working with Porsches.
Don't throw darts at the problem!
Good Luck
Loren
'88 3.2
06-28-2003, 12:02 PM
#9
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Dear Loren,
How about kooling yourself down a bit. This is a 964 forum and I missed the sign off of the car not being a 964. I do not know who you are but you are very aggressive and I do not find this helpful. If you wish to point something out that is fine but you are very new here and please show a little respect for those who have been trying to help people for years on the rennlist forums.
Ciao,
Adrian
911C4
How about kooling yourself down a bit. This is a 964 forum and I missed the sign off of the car not being a 964. I do not know who you are but you are very aggressive and I do not find this helpful. If you wish to point something out that is fine but you are very new here and please show a little respect for those who have been trying to help people for years on the rennlist forums.
Ciao,
Adrian
911C4
06-28-2003, 01:08 PM
#10
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Dear Ingo,
The code you will get when you plug in the RUF chip is 1141. This is quite normal because the later model DMEs have a foreign chip set detect system.
Based on the fact that your installation is in an older model 911 I would advise you just to forget about such things. The shielding is not a problem because I have seen the same issue on 964s on installations that were not originally installed. There is no difference between a ROW and USA M64/01 engine and nor is there is a difference in the DMEs. Only the jumper leads for variants tell the DME where the 964 engine is located.
There are different gearboxes by the way but all fit and can be used.
Ciao,
Adrian
911C4
PS: Please remember we are talking 964 engines here. There is a difference between the 993 ROW and US engines.
The code you will get when you plug in the RUF chip is 1141. This is quite normal because the later model DMEs have a foreign chip set detect system.
Based on the fact that your installation is in an older model 911 I would advise you just to forget about such things. The shielding is not a problem because I have seen the same issue on 964s on installations that were not originally installed. There is no difference between a ROW and USA M64/01 engine and nor is there is a difference in the DMEs. Only the jumper leads for variants tell the DME where the 964 engine is located.
There are different gearboxes by the way but all fit and can be used.
Ciao,
Adrian
911C4
PS: Please remember we are talking 964 engines here. There is a difference between the 993 ROW and US engines.
06-28-2003, 08:38 PM
#11
As usual, you guys always have the answers,
right Adrian?
Do I need to own a 964 to provide info which
I've complied over 15 years working with
Porsches (early 911s thru 996s), BMWs & Mercedes
as an electronics consultant to dealers and
independent shops?
I'm also an electronics engineer who has designed
many chips, and systems for aerospace & the automotive industry.
What other qualifications do I need?
And what qualifies you to post?
Your background, please!
Loren
'88 3.2, a marginal Porsche compared to 964
right Adrian?
Do I need to own a 964 to provide info which
I've complied over 15 years working with
Porsches (early 911s thru 996s), BMWs & Mercedes
as an electronics consultant to dealers and
independent shops?
I'm also an electronics engineer who has designed
many chips, and systems for aerospace & the automotive industry.
What other qualifications do I need?
And what qualifies you to post?
Your background, please!
Loren
'88 3.2, a marginal Porsche compared to 964
06-29-2003, 03:20 AM
#12
Loren:
Since I'm one of the "dart throwers", what exactly is wrong with my advice (I'm an EE too, and I used to program engine electronics, FWIW)?
Although I have to admit I missed the part about the car being a 3.6 transplant, I suggested he reset the DME in case it picked up a transient signal. These things happen. I also stated if it occurs, then he should consider it a real problem. I also suggested that he check cables and connections first, which to me includes grounds. I don't understand how this qualifies as "throwing darts" at a problem.
Just looking for clarification (and a good fight!! <img border="0" title="" alt="[Wink]" src="wink.gif" /> )
<img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />
Since I'm one of the "dart throwers", what exactly is wrong with my advice (I'm an EE too, and I used to program engine electronics, FWIW)?
Although I have to admit I missed the part about the car being a 3.6 transplant, I suggested he reset the DME in case it picked up a transient signal. These things happen. I also stated if it occurs, then he should consider it a real problem. I also suggested that he check cables and connections first, which to me includes grounds. I don't understand how this qualifies as "throwing darts" at a problem.
Just looking for clarification (and a good fight!! <img border="0" title="" alt="[Wink]" src="wink.gif" /> )
<img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />
06-29-2003, 04:27 AM
#13
Let's re-state all posts:
1. owner indicates a hall sensor fault
2. next post indicates this is a common problem
3. next post suggests reseting fault
4. next post suggests clean conn. & check cables
5. mine - possible RF noise
6. mine - check installation and shielding
7. next suggests a DME problem
8. next the owner says the problem re-occurs
9. next suggests ignore code & shielding not
the problem
What is really known about this problem:
1. a 964 motor was installed in an old Porsche
2. the owner gets re-occuring hall sensor faults
What is known about previous 964 random/hall
sensor faults;
Many of my shops and I have found that the
ignition plug connectors not fully pushed
on plugs, bad ignition wires, or oil on
the plug wires causes random faults. I've
seen this where the hall fault come up because
of these. Customers have replaced the hall
w/o luck until ignition wiring checked/fixed.
I've also tried changing the DMEs w/o luck.
Possible conclusion:
The 964 DME system is very sensitive to RF noise
because of the dual ignition and the wiring
layout in the engine compartment. The installation
may not be done correctly. The ignition system
may be causing random faults.
Possible solution:
Check all the grounds and ignition wiring
shielding and all the upper and lower spark
plug connections/connectors and ignition wires.
The troubleshooting process should be done
carefully one step at a time. Check my web site
Systemsc.com under Diagnostics - General for
a guideline.
Working on problems like this are sometimes very
time consuming and not my favorite. If this were
a real 964 the problem would be much easier. The
3.2 retro is somtimes a problem, but the 964
retro is a much greater problem.
Without any additional owner feedback, not much
more can be said. We need more info!
Loren
'88 3.2
1. owner indicates a hall sensor fault
2. next post indicates this is a common problem
3. next post suggests reseting fault
4. next post suggests clean conn. & check cables
5. mine - possible RF noise
6. mine - check installation and shielding
7. next suggests a DME problem
8. next the owner says the problem re-occurs
9. next suggests ignore code & shielding not
the problem
What is really known about this problem:
1. a 964 motor was installed in an old Porsche
2. the owner gets re-occuring hall sensor faults
What is known about previous 964 random/hall
sensor faults;
Many of my shops and I have found that the
ignition plug connectors not fully pushed
on plugs, bad ignition wires, or oil on
the plug wires causes random faults. I've
seen this where the hall fault come up because
of these. Customers have replaced the hall
w/o luck until ignition wiring checked/fixed.
I've also tried changing the DMEs w/o luck.
Possible conclusion:
The 964 DME system is very sensitive to RF noise
because of the dual ignition and the wiring
layout in the engine compartment. The installation
may not be done correctly. The ignition system
may be causing random faults.
Possible solution:
Check all the grounds and ignition wiring
shielding and all the upper and lower spark
plug connections/connectors and ignition wires.
The troubleshooting process should be done
carefully one step at a time. Check my web site
Systemsc.com under Diagnostics - General for
a guideline.
Working on problems like this are sometimes very
time consuming and not my favorite. If this were
a real 964 the problem would be much easier. The
3.2 retro is somtimes a problem, but the 964
retro is a much greater problem.
Without any additional owner feedback, not much
more can be said. We need more info!
Loren
'88 3.2
06-29-2003, 12:25 PM
#14
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Dear Loren,
If you want to check my qualifications to post here I suggest a visit to <a href="http://www.bentleypublishers.com" target="_blank">www.bentleypublishers.com</a> would be your first step. I would possibly advise that you check the rennlist archives back to 1999. Plus a few other sources around the world including well let us leave it there.
If you require my CV, jump on a plane to Switzerland and I shall let you read it.
You are far too aggressive and rude. As a moderator I can delete your rudeness but I prefer to ask you to tone down your posts to the helpful level. We have seen a lot of people claiming this that and the other come and go from these forums. Your help is welcome, your attitude is not. This forum is set up to help people not to insult them. Please re-read your posts before sending them. I really do not have the time to moderate your posts but if you force me to I will.
Maybe you should also consider sponsoring Rennlist. I hope you are not here trawling for commercial business. That is not allowed either.
Ciao,
Adrian
911C4
If you want to check my qualifications to post here I suggest a visit to <a href="http://www.bentleypublishers.com" target="_blank">www.bentleypublishers.com</a> would be your first step. I would possibly advise that you check the rennlist archives back to 1999. Plus a few other sources around the world including well let us leave it there.
If you require my CV, jump on a plane to Switzerland and I shall let you read it.
You are far too aggressive and rude. As a moderator I can delete your rudeness but I prefer to ask you to tone down your posts to the helpful level. We have seen a lot of people claiming this that and the other come and go from these forums. Your help is welcome, your attitude is not. This forum is set up to help people not to insult them. Please re-read your posts before sending them. I really do not have the time to moderate your posts but if you force me to I will.
Maybe you should also consider sponsoring Rennlist. I hope you are not here trawling for commercial business. That is not allowed either.
Ciao,
Adrian
911C4
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grantvs911 (08-02-2022)
06-29-2003, 07:55 PM
#15
Instructor
Thread Starter
Gosh, it seems like I kicked an avalanche loose here. Let's clear a couple of things up here real quick:
- Yes this is a 74 Targa with a 3.6. I did the installation myself. I also installed 993/964 gauges myself. I made the conversion harness (DME to car) myself from stock Porsche parts. A couple of month ago I did the electrical installation of a 993 VarioRAM into a 74 couple. So I do know how to work electronics. You can take a look on my website if you are interested or check out the car when you are in the area.
- I appreciate Adrian's comments and I also understand Loren's comment that an electronic device such as a DME (a SBC with a 8051-derivate microcontroller) is sensitive to transients.
The sensors use shielded wires. However, this shielding is wrapped in plastic and won't go bad unless the entire harness got chopped up at some point. There is also shielding inside the DME box. This is to prevent the computer to transmit radio frequencies (FCC compliance) as well a to shield it from outside RF interference.
Bill, you were nuts on. I was just too lazy to check on the obvious things first. Didn't even bother to get my Multimeter out. Duuh:
The reason for the 1134 fault is/was that the wires to the 3pin connector where busted inside the rubber boot of the connector. I should have checked that first, especially since the connector for the fan belt minder was ripped off of the DME harness completely when I got the engine. Might have happened during the deinstallation of that engine. Or maybe the donor car the got hit in the rear.
- There is no need to start slashing each other. I just wanted to get some feedback on a couple of questions:
*What is the hall sensor signal used for in the DME? (no answer yet)
*How is a bad hall sensor affecting engine performance? My ran fine without it, obviously (limp mode, O.K. that makes sense. How would that get indicated on a stock 964. Is it the central informer throwing up the red ! sign?).
*Why does PET not list this sensor as a replaceable part (no answer yet)?
*where would I get one in case (no answer yet)?
Could a Bosch motronic DME specialist chime in here please. I know there is a guy who completely reverse-engineered a 944 Motronic complete with schematics somewhere.
Ingo
- Yes this is a 74 Targa with a 3.6. I did the installation myself. I also installed 993/964 gauges myself. I made the conversion harness (DME to car) myself from stock Porsche parts. A couple of month ago I did the electrical installation of a 993 VarioRAM into a 74 couple. So I do know how to work electronics. You can take a look on my website if you are interested or check out the car when you are in the area.
- I appreciate Adrian's comments and I also understand Loren's comment that an electronic device such as a DME (a SBC with a 8051-derivate microcontroller) is sensitive to transients.
The sensors use shielded wires. However, this shielding is wrapped in plastic and won't go bad unless the entire harness got chopped up at some point. There is also shielding inside the DME box. This is to prevent the computer to transmit radio frequencies (FCC compliance) as well a to shield it from outside RF interference.
Bill, you were nuts on. I was just too lazy to check on the obvious things first. Didn't even bother to get my Multimeter out. Duuh:
The reason for the 1134 fault is/was that the wires to the 3pin connector where busted inside the rubber boot of the connector. I should have checked that first, especially since the connector for the fan belt minder was ripped off of the DME harness completely when I got the engine. Might have happened during the deinstallation of that engine. Or maybe the donor car the got hit in the rear.
- There is no need to start slashing each other. I just wanted to get some feedback on a couple of questions:
*What is the hall sensor signal used for in the DME? (no answer yet)
*How is a bad hall sensor affecting engine performance? My ran fine without it, obviously (limp mode, O.K. that makes sense. How would that get indicated on a stock 964. Is it the central informer throwing up the red ! sign?).
*Why does PET not list this sensor as a replaceable part (no answer yet)?
*where would I get one in case (no answer yet)?
Could a Bosch motronic DME specialist chime in here please. I know there is a guy who completely reverse-engineered a 944 Motronic complete with schematics somewhere.
Ingo