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porscheguru
porscheguru, Porsche technician
Category: Porsche
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Experience:  Exclusive Porsche only technician for over 28 years
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Matt, The sensor readings from the oscilloscope that you

Customer Question

Hi Matt,The sensor readings from the oscilloscope that you requested are:DTC 1.54V and RPM 2.5VA picture of the stud is attached.What next?Many thanksSam
Submitted: 1 year ago.
Category: Porsche
Expert:  porscheguru replied 1 year ago.

Can you take a picture of the oscilloscope reading?

Expert:  porscheguru replied 1 year ago.

Without seeing the pic, it is too low. Has to be above 3 vojts. It is midnight in my location and I am going to bed now. I still have a fix if the ref sensor is truly 1.5 volts. Chat in the morning

Expert:  porscheguru replied 1 year ago.

I just wrote a ton of info and a refresh killed it! OK, adjust the gap to the speed sensor like I said previously. Make sure the reference sensor is not above the allen. Turn the engine to get the allen away from the sensors. Loosen the allen bolts, push down til the speed sensor hits the flywheel. Pick up ever so slightly just to put a tiny gap between the speed sensor and the flywhel. This will make the reference sensor correct. Rotate the engine by hand several times before cranking the engine to make sure nothing hits or scrapes. Either remeasure voltage or try to start the car. If the injectors start clicking your in good shape.

Customer: replied 1 year ago.
Hi Matt,
Thanks. Here are the oscilloscope photos.
The speed RPM sensor wave form looks nice. The DTC spiky wave form is a bit spiky.
Let me know what you think and I will then proceed to adjust the gap accordingly - unless you advise otherwise.
Many thanks
Sam
Customer: replied 1 year ago.
RPM sensor
Expert:  porscheguru replied 1 year ago.

Ok, adjust as I described and see if you can improve the signal. I like to see it stronger

Expert:  porscheguru replied 1 year ago.

OK look at this document

http://www.mediafire.com/download/uv71kwfq0bzh5o2/944speed_ref.pdf

Your ref sensor is not strong enough to start the engine. Your speed sensor is good. I like to see more than 3 volts for good starting in the winter. You are going to need to make my suggested adjustment if the basic adjustment does not work. That is the reason for my proposed phone conversation. It will be easier to describe it for you to do it properly.

Expert:  porscheguru replied 1 year ago.

Your reference sensor is less than 2 volts

Customer: replied 1 year ago.
Hi Matt,Thank you. All good and understood.A question: Does the Waveform picture for the reference sensor look like what you would expect, based on your experience with other vehicles?I am on the road until about 5 PM Eastern time and wilI contact you for next steps, as soon as I get back to the carWarmest regardsSam
Expert:  porscheguru replied 1 year ago.

You see, the scope patterns have subtle differences from scope to scope. I am not worried right now about the shape but the amplitutude or the amount of voltage created. Less than 2 volts is real hard to start the engine if not impossible. it is a sweet sound when you get the voltage adjustment correct and then crank it and hear the injectors clicking. After 5 is good for me

Customer: replied 1 year ago.
Hi Matt,
Thanks for the scope info.
I tried adjusting the bracket, but those two allen bolts are a PITA to access from up top, due to the tight spacing.
I will grind down some allen keys between 4, 5 and 6 to get them into the tight space, when I next work on the car. This will likely be in ten days, after a mini trip. I will revert to you then.
Best until then and many thanks for your hand-holding.
Warmest
Sam
p.s: You aren't perchance in the Atlanta GA area are you? About 20 years ago a friend from down there gave me a black hat with a yellow /white embroidery that had a Porsche 911 outline and read "Matt the mechanic". :-)
Expert:  porscheguru replied 1 year ago.

No not me. Matt is another expert that tries to answer question. I have a ton of real world experience and my name is ***** *****

I think you should close this chat if it is not going to be active for 10 days. I want to tell you how to adjust and not even touch the bracket but we need that phone call. So I guess initiate a phone call for me when you return.

Ok, if you ever need help in the future you can ask for me by request. I have a ton of

Porsche dealer experience.
Please remember to rate service using the rating page so that I may receive credit.

Thanks
If for any reason, you can't rate my answer OKAY, GOOD, or EXCELLENT today.
Please reply and let me know why, so I can help you more thoroughly.
Thank you! If you ever need addtl help, do not hesitate to request me. I have been a

professional Porsche ONLY technician for 30 years!
user name: porscheguru

Ok, if you ever need help in the future you can ask for me by request. I have a ton of

Porsche dealer experience.
Please remember to rate service using the rating page so that I may receive credit.

Thanks
If for any reason, you can't rate my answer OKAY, GOOD, or EXCELLENT today.
Please reply and let me know why, so I can help you more thoroughly.
Thank you! If you ever need addtl help, do not hesitate to request me. I have been a

professional Porsche ONLY technician for 30 years!
user name: porscheguru

Customer: replied 1 year ago.
Hi Frank,Firstly, sorry for calling you Frank.Can u write me to outline your solution and I can then call for details when I get backRegardsSam
Customer: replied 1 year ago.
Oops Matt
Expert:  porscheguru replied 1 year ago.

I will put it into a pdf file and send the link to you

Expert:  porscheguru replied 1 year ago.

Here you go Sam

https://www.mediafire.com/?np0qts2vkfs297f

Here is the info you reuquested

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