Porsche Enthusiasts Club Forum
https://forums.tipec.net/

No Start/No Tacho Bounce/Speed-Ref Sensors?
https://forums.tipec.net/viewtopic.php?f=25&t=23694		 Page 1 of 1
Author:  scam75 [ Thu Nov 22, 2018 9:21 am ]
Post subject:  No Start/No Tacho Bounce/Speed-Ref Sensors?
Morning All

Was greeted with a no start, no tacho bounce this morning in sub zero temps. Nice. Had noticed last week a no start incident, isolated, failed to notice tacho as it fired up next try. Anyway it wasn't having it this morning. So opened the bonnet to wiggle the speed/ref sensor bracket. Noticed bracket was loose, floating about, anyway starts first time after a wiggle. Noticed I needed a splash of oil, so switched off, topped up oil, secured and tightened 10mm bolt holding bracket, started first time, no dramas.

So firstly, does a turbo have a speed and a reference sensor, sure I read it just has one? The bracket seemed to have one plug going into it from O/S and then a couple leaving it from the N/S. Not really got a clue what they all are. Secondly, can this cause an engine cut-out whilst driving or will it just prevent a start when playing up? Thirdly, what advice? Obviously the bracket is no longer floating about so that will help. Is it worth unplugging it and spraying in some contact cleaner or is it likely to fall apart as I've read previously? The car had a new speed or ref sensor (not sure) about 10 years ago just before I bought it I noticed from the history.

Anyway, thanks all in advance!

Edit to add, I do have 2 sensors, and they are properly clipped together with metal clips in place, and the wiring and plugs all look in VG condition.

Also posted on PCGB.

Stuart
Author:  Prophead [ Thu Nov 22, 2018 8:21 pm ]
Post subject:  Re: No Start/No Tacho Bounce/Speed-Ref Sensors?
That's a bugger.

I have read on other forums / FB of issues with the wiring failing an inch or so from the plug, which might explain why it started after a wiggle. It could just be that with the bolt coming loose on the bracket the sensor moved enough so as not to produce a signal. And yes, dodgy ref sensor = no start (ask Roy :lol: ), might be worth having one in the draw next to the spare DME relay.
Author:  scam75 [ Thu Nov 22, 2018 9:14 pm ]
Post subject:  Re: No Start/No Tacho Bounce/Speed-Ref Sensors?
Yes Sean I'm hoping securing the bracket does the trick. Was fine to work and back so fingers crossed. The wiring does bend an inch or so before the plug so that could cause an issue after 30 years. Similar to the AFM connector on the loom on a turbo that has a similar bend. Anyway see how we go!

Stuart
Author:  ROY924GT [ Fri Nov 23, 2018 5:11 pm ]
Post subject:  Re: No Start/No Tacho Bounce/Speed-Ref Sensors?
aye I had one of the sensors go on my car and it has only done 95000 miles, way less than your car.
it turned out to be only one faulty sensor, I had both in stock so replaced both.
i know 2 other 944 that had those sensors go, so my be a good idea just to get 2 new ones in there.
good luck.
Author:  scam75 [ Sun Nov 25, 2018 10:52 am ]
Post subject:  Re: No Start/No Tacho Bounce/Speed-Ref Sensors?
Thanks Roy. At least one has been changed about 10 years ago. Saw that in the history file. Will double check to see if both were replaced. It's been fine since I tightened the bracket but tbh I expect it will re-occur at some point.

Stuart
Page 1 of 1 All times are UTC
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
http://www.phpbb.com/