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The strangest thing...
i have a 1974 and the PO put in a 1977 2,7 engine. All works no problem... Except the tach which have been dead since I bought the car...
So here is the puzzle... When i get to really low rpm's for example when stalling, the tach will bounce a couple of times... Nothing crazy... Just above 1000 rpm's ... Anyone seen/experienced this??? Has it something to do with a problematic signal? These old cars sure can act weird...:-) Best from Søren
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My 69E project ... http://www.youtube.com/user/ditster666 |
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05-31-2015, 12:28 PM
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Registered
Join Date: Jun 2009
Location: Manhattan Beach, California. Factory Delivery-Original owner-Retired engineer
Posts: 5,238
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Tach.
Quote:
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1986 911 Targa. Per Road and Track magazine: Only in L.A.: In the window of a bar in Hermosa Beach, California. "Happy Hour prices during all car chases." |
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05-31-2015, 12:41 PM
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76 911S Targa
Join Date: Oct 2010
Location: Idaho
Posts: 1,150
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I think you have a mismatched signal from the 77 engine to the 74 tach. I don't remember when the sender/tach changed but I think it was during this period. That is where I would look. I vaguely recall something about the number of pulses per second being different. Someone on this board makes an adapter.
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76 911S, 2.7, Bursch Thermal Reactor Replacements, Smog Pump Removed, Magnecors, Silicone Valve Cover Gaskets, 11 Blade Fan, Carrera Oil Cooler, Turbo Tie Rods. |
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05-31-2015, 01:38 PM
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Join Date: May 2014
Location: NW
Posts: 21
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I had something similar with a 2.7 replaced with 3.0...Tach was working but when slowing down at stoplight, every once in awhile the tach would bounce. Thought it might be VR and messed around with troubleshooting (monitored voltage, connections, looking at all grounds, etc, etc)...in process, wiggled some wires in engine compartment on left side and made it worse. Traced it down to a bad electrical connection in the engine compartment.
In your case could also be at back of tach connections. |
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05-31-2015, 01:41 PM
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I have heard about bad regulators, but everything else seems to be working.
Mismatched signal.... Hmmm... What kind of signal should i be looking for at the tach end? What instrument to use to check... I dont have an oscilloscope...:-) Søren
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My 69E project ... http://www.youtube.com/user/ditster666 |
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06-01-2015, 10:34 AM
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I have one. Ship your car to me and I'll test it. Be sure to include return postage. I'll get it back to you, I promise.
 Is this the guy who makes adapters?
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72 911T 2.4 MFI 2017 Escape SE 2.0 turbo 2020 Honda Civic Touring Sport 1.6 turbo 10' Madone 5.2/17' Lynskey ProCross |
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06-01-2015, 10:57 AM
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Yep tach signal will be wrong,Tach- Adapt is sold by are host,the appear to work very well.
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1985 944 2.7 motor,1989 VW Corrado 16v,57 project plastic speedster t4 power,1992 mk3 Golf,2005 a4 b7 qt avant 3.0 tdi,1987 mk2 Golf GTI,1973 914,2.2t to go in. Past cars, 17 aircooled VW's and lots of BMW's KP 13/3/1959-21/11/2014 RIP my best friend. |
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06-01-2015, 11:56 AM
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Porsche
Rust Rocket
Madone
Porsche 914
The tractor
