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AndrewCologne AndrewCologne is offline
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Join Date: Aug 2015
Location: Cologne / Germany
Posts: 85
Thanks for all your input.
Yesterday the car was running a lot and I figured out that the stutter especially at high RPMs starts when the engine is hot/warm. The engine suddenly doesn't pull that strong as it was.
I stopped the car and the idle was normal. In my experience, if the Relay is the guilty then the idle should be rough or not normal as well. So I did pull the OSX-relay and yes, the idle drops and gets rough as it should be. So ... Im a bit confused.
Then at the evening also the idle sometimes gets rough as well ... in the same way like known from a bad OSX-relay. But suddenly .. as written above, the idle gets stabilized again.

Originally Posted by Sub8 View Post
If you have a suitable multimeter you can also log the dwell or duty cycle (depending on meter) at the connector under the passenger seat.
I thought that can be only done via the testing port in the engine compartment?
Where is that plug/contact/connetor under the passenger seat? I assume its somewhere at the ECU, right?

However, ... that diagnostic above tells me that there is somewhere an electrical circuit problem in the ECU/FV system. So now I've to figure out if the ECU is bad, the Frequency valve, the wiring loom or if the relay again is flawed.

As first step of the test I will do is to pull the relay and use my special y-wiring to bypass the relay via that kind of jumper so both 87 terminals of the OSX-relay socket will get terminal 30 current directly.

I hope it won't be a bad Frequency valve, as its quite expensive. Not mention the price of an ECU.

Best regards from Cologne!
911 SC 3.0, 1982, black, US model
Old 05-01-2018, 10:52 PM
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