[Pams968]

4 years ago after some major work (I threw a rod - ugh), my "Check Engine" light was coming on sporadically, usually going off again.  Then on again.  Had the car checked, fault code showed #31 & #32 - Knock Sensors.  Had those replaced.  Car fine for a few months and then the engine light again, same knock sensor code. 

 

Here's the weird thing:  From a stop, if I rev the car over 3500RPM the engine light goes off immediately, usually doesn't come on again.  I did this for 3+ years, and then it was on all the time.



Had an oil change, a few fuses, and a new battery installed 3 months ago and while the engine light came on on the way home, it's been off since.  Until today.  Reset it manually (drives me crazy when that light is on) and we'll see what happens.

 

I did a lot of searching for similar issues - ignition switch?

 

Don't know if it's related, but my odometer and trip meter also don't work.  Had the instrument cluster rebuilt 4 years ago, but they stopped again last year.  The speedometer sticks and the temp gauge likes to point due north.  Until I tap it and then it comes back down.  Same with speedometer, a light tap and it bounces to speed.



Also have a weird thing going on with my A/C - sometimes turning it on causes the heat to come on.  I just keep switching it back and forth and eventually A/C works again.



My car has only been to a dealer, and specialists in the DFW area but they seem flummoxed as to what the issues are.  I've driven this car for 20 years so I know it's quirks.  I honestly don't think there's an engine issue and I've paid thousands of dollars in diagnostics....    Being a 968, there just aren't that many people familiar with it.



Any help y'all could provide from personal experience would be greatly appreciated!

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[Waylander]

Can you tell me about its living environment, does the air get damp at all,



These cars really do suffer with bad earths, I always start by cleaning every earth point



Then start working through the connectors for the odd behaving parts, I had a very similar thing with my knock sensors but we dont have a ECL in the U.K. cars



Kept seeing the fault in durametric, I bought new sensors but it was corroded plugs that was the issue, two new plugs fitted never had the issue again



The ignition switch can have some strange effects, but you can just wiggle that to test if it fixes anything



You only need the rear plastic part, about 90 dollars, and its a bit fiddly but no need for a specialist

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[Pams968]

I live in Fort Worth, Texas and it can get very humid here.  

 

By earths do you mean grounding points?  ECL - No Engine Coolant in UK?

 

Did some Googling - interesting on the ground wires, my 968 EATS batteries, like every 2-3 years.  And I've had some major electrical issues (see my post about the failed wire harness).  I wonder if that's it?

 

Will try wiggling - I seem to do alot of that with this car lol.  But I love her all the same.  I say she leaks and she creaks but I prefer her to my Cayman S, much more fun to drive.

 

I'll have to check the last time I had new spark plugs, don't think it was that long ago.  Unfortunately, I don't do the work on my car, it's hired out and I barely trust anyone at this point.  Sometimes I don't think they listen to me because I'm a woman.  But a woman who's driven the car for 20 years and knows EVERY sound it makes and when something's not right.

 

What part is the rear plastic part you mentioned?

 

Thanks for the input!

Pam

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[Waylander]

Ah ok



The brass and copper connections can corrode quite quickly in humid conditions



ECL engine check light in the early 90s was only required for sales of cars to the USA



To sort your questions and information in to positive answers



Your failed harness was possibly the alternator charging harness, very common fault



The earth points on the car are quite numerous

2 by the headlights

1 on the engine

4 under the dash

2 in the boot



They cause all sorts of weird issues when not making a good connection



The ignition switch is in two parts, the front part that has the key hole, the rear part which is a plastic switch, the rear part wears especially if you have a heavy bunch of keys



Batteries getting munched can be caused by a few things, over charging the battery, a big drain on the battery when the car is not in use



I am sure there is someone on here that can point you at a specialist in your neck of the woods that knows 944s the issues are just the same as the 968



I dont think the spark plugs will be having any effect on the knock sensors

But if they are not working correctly or if the engine computer thinks they are not working it will be reducing the engine power quite a bit

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[dlearl476]

Yall aught to do yourself a favor and buy yourself some Caig de-Oxit Gold and treat every connector you ever unmake/make when youre working on your cars. Starting with the grounds Waylander mentioned.



It comes with a variety of applicators. I find the pin oiler and the bottle/brush the handiest for automotive work.



   

https://www.markertek.com/product/g100l-...crEALw_wcB



Its expensive, but worth every penny. (Its GOLD Jerry!) And that bottle is a lifetime supply for a DIY guy.

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