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Faulty Boost gauge readings

g59tester

g59tester

PCGB Member
Member
I'm going to bite the bullet and remove the instrument cluster to repair my speedo. I also have an issue with the boost gauge. The needle rests on the bottom stop until i start the engine. The needle then registers '1' on the scale and then gradually sinks back to the bottom stop over a period of a minute or so. At no time does it react to engine revs despite the turbo clearly working. any ideas? Is it the instrument? connections electrical or pneumatic?

Any other issues likely to cause problems? I know getting the steering wheel off means slackening the nut but leaving it in place until the wheel is free. Is freeing the wheel likely to be an issue?
Is getting the multi-connectors off the cluster straight forward.... I dont feel too confident about doing this!

Eddie
Cayman S 2007
944 turbo 1988
 
Eddie,
Seemed a but quiet so I thought I better offer some comments!
I have done all this on my 86 turbo, replaced the little wheel inside the speedo, the original having been made of toffee or something like it, any way its all pretty straightforward and do-able I'd just advocate patience and avoid forcing anything because it will all be pretty brittle.
My very simple original steering wheel was easy, just ease the centre horn push gently off the 2 push fit clips and avoid stretching and breaking the electrical connection. You can get to the retention nut with an extension and the wheel loosened off easily in my case. Not sure if an '88 is any different.

Find all of the screws retaining the bezel and trim and dont drop anything! the instrument cluster is the most awkward to ease out and disconnect the ribbon connectors moving the clamp levers out and pulling the connector blocks off.

I was talking to my friendly independent Porsche specialist Friday and he reckoned when you put it back together at least two of the gauges will fail to work so there will be a bit of in and out and some contact cleaner to get it all up straight in his and my experience.

Main things, simple job just requires endless patience and a gentle touch.
 
Hi Thanks for your input... sorry not sure of your name

I've got it all dismantled down to removing the speedo from the cluster. I had to get someone to help me hold the wheel while I slackened the large nut in the column apart from that it was OK
the mechanism that resets the trip meter doesn't seem to be quite right... its flopping about.

Also any ideas how I can test the boost gauge?

Thanks Eddie
 
You did well by not punching yourself in the face with the horn pad!

I’ve had the instrument cluster in and out a fair few times and never had any issues with things not working afterwards- that said, don’t try and move the original wiring about too much and put it back in the position it came out in. The connectors on the back have an arm either side, you pinch these in and the connector springs out easily - you’ll be fine.


The boost gauge is electrically operated as there are all sorts of funny dividers used to get it going when using a standalone ECU - I haven’t got this quite cracked on mine yet but TBH once there is any boost to register on the gauge then my eyes are firmly on the road!
 
I follow your thinking but it would be nice for it to be working......
Should I take the opportunity to spray all the 'edge' connectors with contact cleaner?

I've got the drivers seat out also to get the bolster repaired so the car is really looking a bit stranded

thanks for your input

Eddie
 
Hi Eddie

yes to giving all contacts a good clean, you may find that the boost gauge will work again purely from being disconnected and then put back again. Most issues with cluster gauges are the result of corroded contacts which respond well to a good clean.
I can't recall where the wiring goes, I would assume to the KLR/DME (perhaps someone else can answer this?) but if so and still not working on reassembly then it may be worth taking a look at the multiblock connection in the DME/KLR units to check for any corrosion there.

Regards

Pete
 
Always worth getting a proper standalone boost gauge. Especially when your boost passes the end of the standard one....[8D]

Stuart
 
Hi Pete, can you just elaborate a bit further on the DME/ KLR issue. I've recently had some issues with the DME ignition/petrol pump relay it seems a bit intermittent. I bought a new relay and when i put it in it didn't workre-inserting it a few times and it seems ok but sometimes takes a bit longer to fire up. Is this the same relay you are talking about and where is the multiblock connection you are talking about? in the instrument cluster?

Eddie
 
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