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Friends of Warren
Join Date: Feb 2004
Location: Surrey, UK
Posts: 3,133
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3.6 timing sensor
I screwed up... Truing to fix the hesitation problem (at 2.8k and 3.5k... everytime... under load and under no load) this weekend I swapped the DME and the ignition switch with no luck.
So this afternoon I tackled the timing sensor.... Well now the car doesn't even start. And when I put the old one back on... same results.... Is there a particular way this this is supposed to be mounted? Is the little rubber lip (which wraps aound the metal sensor) supposed to touch the flywheel or not? I am exhausted as this timing sensor is placed in a very unaccessible place (at least if you dont have a lift)... I am ready to give up and have AAA take the car to the shop.... Any ideas? Thanks |
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08-21-2005, 03:24 PM
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The gap between the sensor and flywheel ring gear is 1.0 ± 0.2mm
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Bill Verburg '76 Carrera 3.6RS(nee C3/hotrod), '95 993RS/CS(clone) | Pelican Home |Rennlist Wheels |Rennlist Brakes | |
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08-21-2005, 03:51 PM
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Friends of Warren
Join Date: Feb 2004
Location: Surrey, UK
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Thanks Bill... I am going to give it one last shot....
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08-21-2005, 04:41 PM
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Make sure all the coinnections, both + and ground are as solid as possible. These systems are very sensitive to the quality of their connections to the world.
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Bill Verburg '76 Carrera 3.6RS(nee C3/hotrod), '95 993RS/CS(clone) | Pelican Home |Rennlist Wheels |Rennlist Brakes | |
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08-21-2005, 04:54 PM
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Friends of Warren
Join Date: Feb 2004
Location: Surrey, UK
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Not working still... I tried all the possible gaps...
As per connections... there is only one plug (female) that matches to the male in the engine compartment.. Am I missing something here? I am going to call it a day. Will call Timmins tomorrow... Thanks again for your help! |
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08-21-2005, 05:57 PM
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Matteo,
The sensor is a hall-sensor that reacts to the teeth on the flywheel. If you have access to a scope you should be able to see a sine wave of 3volts peak to peak once you crank the engine. Without a scope a good way to telll whether the DME and the reference sensor are working is to monitor the DME relay. It should be somewhere under your drivers seat. Once you switch the ignition to RUN you should be able to hear or feel a click (1st stage of DME relay turns on). Once you crank the engine you should hear the second click (2nd stage of DME relay turns the fuel pump on). You might place your hand on the relay while a helper does the cranking. If the DME releay does not turn on then you need to start to check signals at the 54 pin. BTW: Have you replaced the DME relay. I would start there. If you are good with a soldering iron you can fix them. They are notorious to fail. Ask me how I know. First they cause hesitation then complete malfunction. I don't know if the Timmens harness these days uses the period-correct square shaped DME relay (that fails) or the round style from a Carrera. I have seen a round style on one of his conversion harness but you never know. Good luck, Ingo
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1974 Targa 3.6, 2001 C4 (sold), 2019 GT3RS, 2000 ML430 I repair/rebuild Bosch CDI Boxes and Porsche Motronic DMEs Porsche "Hammer" or Porsche PST2, PIWIS III - I can help!! How about a NoBadDays DualChip for 964 or '95 993 |
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08-21-2005, 06:12 PM
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Friends of Warren
Join Date: Feb 2004
Location: Surrey, UK
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The problem was the connector in the engine bay. I must have pulled a wire out and could not see it.
I had the car towed to the P-shop... and they fixed the problem in 1h our... Thank you for your help and support! |
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09-19-2005, 12:12 PM
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I'm curious Matteo~
Now that you have the car started.... Is the hesitation problen gone? I've been chasing after the exact same problem for some time now.... I've replaced the DME relay, CHT sensor, and both sensors at the flywheel.... Also, plugs, wires, cap & rotor, new ground strap, battery, fuel pump, fuel regulator... swapped out air box, fuel rail, and computer from a perfect running car.... All to no avail!! Just curious if you found the definitive answer to the problem!!!
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'85 Carrera Coupe, Marble Grey #118 JP/R6 '93 Lexus SC400, '00 Ford F-150 '70 911T- 2.7 (SOLD) |
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09-19-2005, 02:50 PM
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Registered
Join Date: Dec 1999
Location: Novato, CA
Posts: 4,740
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Quote:
Joe |
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09-19-2005, 02:55 PM
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Large Registered Member
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Swapped the whole damn box! Meter and all!
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'85 Carrera Coupe, Marble Grey #118 JP/R6 '93 Lexus SC400, '00 Ford F-150 '70 911T- 2.7 (SOLD) |
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09-19-2005, 03:07 PM
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Registered
Join Date: May 2003
Location: Manhattan Beach, CA
Posts: 2,350
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"The sensor is a hall-sensor that reacts to the teeth on the flywheel." - Ischmitz -
The speed/ref sensor is a magnetic pickup (variable reluctance) and not a Hall sensor as used on the 964 for cylinder I.D. A Hall device is a semiconductor device whose conductance is affected by a magnetic field.
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Have Fun Loren Systems Consulting Automotive Electronics '88 911 3.2 '04 GSXR1000 '01 Ducati 996 '03 BMW BCR - Gone |
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09-19-2005, 03:23 PM
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Friends of Warren
Join Date: Feb 2004
Location: Surrey, UK
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Patrick
yes the stumble/hesitation problem is gone... The car is now incredibly responsive. Whilst I was in there I changed the DME, rotor caps, ignition coils, spark plugs etc but the problem was always there.... And as if by magic with the new timing sensor the car is perfect.... |
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09-20-2005, 03:27 AM
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Large Registered Member
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Matteo...
Can you clarify? When you say timing sensor, do you mean the reference sensor at the flywheel? And when you say you changed the DME, did you mean the DME relay, or the entire computer??? Thanks, and congrats for finding your fix!!!
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'85 Carrera Coupe, Marble Grey #118 JP/R6 '93 Lexus SC400, '00 Ford F-150 '70 911T- 2.7 (SOLD) |
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09-20-2005, 09:22 AM
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Friends of Warren
Join Date: Feb 2004
Location: Surrey, UK
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Patrick
By timing sensor I mean that reference magnetic sensor at the flywheel. And yes we changed the entire DME. I bought this engine (3.6 Vram) from Steve Timmins and he did everything he could to help me, including sending a new DME. |
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09-20-2005, 09:56 AM
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Large Registered Member
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Thanks for responding Matteo!
I was curious, as I replaced my flywheel sensor too, but problem is still there... I also swapped a DME unit from a perfect running Carrera, and still the problem exists... I'm left with the possibility now I suppose, that the harness might be bad, or perhaps a short in one of the 10 million wires.... Ugh...
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'85 Carrera Coupe, Marble Grey #118 JP/R6 '93 Lexus SC400, '00 Ford F-150 '70 911T- 2.7 (SOLD) |
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09-20-2005, 10:04 AM
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Irrationally exuberant
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Quote:
Are you running a 3.6 like 911teo's? A 3.2 and a 3.6L motors are going to have significant differences. Hesitation could be caused by running lean. Possibly causes are air leaks after the air meter, lazy O2 sensor, low fuel pressure, clogged injector(s), etc. I think it is time to stop replacing parts and start measuring things instead. -Chris
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'80 911 Nogaro blue Phoenix! '07 BMW 328i 245K miles! http://members.rennlist.org/messinwith911s/ |
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09-20-2005, 11:43 AM
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Large Registered Member
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That's just it Chris...
My Wrench and I have been running diagnostices with the $10k special tool designed specifically for the motronic system. Everything shows up as within parameters even while the problem is occurring... I'm running a 3.2, however the proiblem noted above is very similar to the problem I'm experiencing. Don't both motors run the similar 2 sensors at the flywhell anyway? I've also had the fuel rails swapped from a different Carrera, and had no affect. Fuel injectors were removed and flow tested... Air meter swapped from different car as well... When o2 sensor removed, the problem is less pronounced, but definitely still there.... I'm leaning more towards a bad wire in line with the DME?
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'85 Carrera Coupe, Marble Grey #118 JP/R6 '93 Lexus SC400, '00 Ford F-150 '70 911T- 2.7 (SOLD) |
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09-20-2005, 11:50 AM
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1976 Porsche Carrera 3.0
1995 Porsche 993 Carrera Coupe
1974 Porsche 911 Targa 3.6
The Blue Pheonix
