"German girlfriend" ill

[George Elliott]

For 4 years I have run a 944T, and I follow the theads here with inrerest. My 1989 car has 120k miles and all the running repairs that you know about, - my other half understands [] the wise investments necessary to keep my 951 happy, and so my 951 has become known as my German girlfriend [8D].

My most recent mod today was to fit an adjustable voltage regulator, and after refilling the coolant and a five mile drive she's taken ill. I had improved dash lighting, faster wipers, better lights, then at the change up point in 3rd gear when one is pressing on - the engine ceased to produce power and the electricals all slowed up, slow wipers, dim lights etc.[&:]. Hard shoulder....
The engine attempts to run, but falters and dies if the throttle is touched, or dies eventually if left at tick-over. The battery has also lost its belly, going flat very quickly. I have tried a new battery and DME relay, - without success.
I have a specialist to talk to about it tomorrow, but any thoughts would be appreciated.
The pre-mod dash volt meter typically read 11.5v to 12.5v. When I set the adjustable one it read 13v on the dash, but I did note that across the battery terminals the reading on a Test Meter was 16.3v. (All readings are at tick-over). I did not measure the battery reading pre fitting the adj regulator. The engine was noticably crisper while it lasted.

George

fyi she was previously reg'd as ALS 56Y, which some of you may recall from 911&PW running reports years back.
also, I hardly know how to use this forum but here goes.....

 

[Mark Elder]

I don't understand why you don't try removing the adjustable voltage regulator and going back to the good old 12 volts that you car was happy with? Seems that was the thing that introduced the problem.

 

[sawood12]

Now i'm no electrician but my rudamentary understanding of electricity is that if you change the voltage then the current is also affected, i.e. if you increase voltage you would also increase current as the resistance remains constatne and I don't think there is a current regulator anywhere in the car. So what is the affect of increasing both current and voltage on the cars electrical system, and i'm not takling about the affect on the ancilliaries like lights and windscreen wipers, but the effect on the ignition system? Are the symptoms of your engine running problems electrical? Maybe the higher voltage and current is playing havoc with the ECU or the coil.

 

[George Elliott]

Mark, I have a return to standard in mind but the symptoms lead me to believe it won't be that simple, we'll see.

Scott, I'm not a spark either, but I would agree the electrical side of the engine management is where my problem lies. I reckon the ignition circuit is the area where the problem and will try the coil & DME control box. The higher voltage is no longer present following the fault occurring. Wonder why the voltage readings before the fault were so different between the Dash & across the Battery. Is it just the long lead to the back of the car.

Thank you both for your comments, I'll keep you posted.

George

 

[Peter Empson]

Hi George,
The volt meters on our cars are generally pretty poor so I wouldn't trust them at all (I suspect its an earthing issue), its always best to use a meter if you're doing any kind of setup, so it sounds to me like you may have inadvertently run it all at too high a voltage.
I hate to say it but something sounds fried to me, but I wish you the best of luck when you have it checked over today and pray that it isn't the ECU.
Best regards,
Peter.

 

[George Elliott]

I agree with those comments, but what value should I be reading at what point in the circuit. Is across the battery relevant? I saw the 16.5v at the battery and thought it a high reading before the test drive when the fault occurred, but the dash reading was OK so I left it. A mistake on my part.
Any readings you folks can give me from your cars would be of interest. Just so they are consistently measured, if you do it, do it on a warm engine at tickover.

thanks George

 

[Fen]

I'd agree with Peter.

In all the time I've been around the 944 I have never heard of an adjustable voltage regulator mod, which leads me to suggest there is nothing wrong with the voltage regulator the cars have as standard. I think you addressed an under-reading voltmeter by turning the electrics up to 11 rather than fixing the meter. I hope I'm wrong, but I imagine you fried at least one component from a longish list including alternator, battery, ECU, loom, relays etc. etc.

 

[George Elliott]

Hi Fen, I'm 95% sure I actually came across the idea of the volt reg from a thread here 2 or 3 years back. I can look up the name of the guy in the US who supplied the kit - not that anyone will want it now.

But it turns out I've been lucky. She's fixed [] [] [].

The Car has or until an hour ago had a Sci-vision kit which I found improved response,(crisper not faster) also rich running at start-up, and general drivability.
After i left a message last night, Promax called me back a couple of times this am with detail questions to help. Their suggestion was, "on the basis that some elec' spike protection exists in the cars elec system, (some spike[&:]) and bearing in mind the car still attempts to run, refit the old AFM". So, after turning down the adj volt reg' - i did the AFM refit, and it worked.
Only problem is the engine now runs like it did last time the AFM was on it. Not a problem but I need to get the Sci-vis fixed.
The Sci-vision is a 2 component kit, a Bosch Mass flow Sensor (MFS) and a circuit which translates the MFS signal for the ECU, (as I have no doubt you will know, and in greater detail than me!) but, I have opened the circiut enclosure and found no obvious elec damage (burnt chip/resistors etc) then I slotted the Bosch tamper proof screws on the MFS, to see if there is any damage there, once in there I cannot see a fine wire like i expect in the MFS. - but as they say here in Ireland, - I may as well be looking in the hedge, because i don't know what I'm looking for!
Promax have offered to investigate a repair.
So, in summary, I feel fortunate because the Sci-vision kit acted as a "fuse" in an overvoltage circuit and protected the other components.
I still have the adj reg on the car. I have been advised an upper limit of 13.8v at the Battery, and have set it to 13.3v at 2000rpm. At the fuse-box I also have 13.3v. On the dash display I have 12.1.[8|]

I'm still interested in the values of a standard car.

Thanks for your response, - i hope you won't mind me saying that i particularly value your input to this forum on 951 matters, and hope you will revive yours ( I don't expect you'll get fed up of the squashed beetle, but I think you'll miss the balance and stability of the 44? )

Finally, Andrew, Roger at Promax - thanks for your guidance.

George

1989 944T, 250[] hp (fit horses)
1991 RSsquashed beetle, std, rhd.

 

[Diver944]

Glad to see you've got to the bottom of it George. I've never heard of an adjustable voltage regulator either and I can't see what any advantage would be to our cars. Is your original voltage regulator broken or can you refit that also to save the risk of burning anything else out?

 

[Fen]

Well, I always like to be wrong when it means someone has avoided a big bill.

My '44 will be back sometime, somehow. I'm not actually missing it all that much (I'd all but stopped driving it during this sort of weather last year), but the squashed Beetle is all but finished in terms of rectifying niggles so next big expenditure can be on major engine work for one of them. Not entirely sure which yet though...

 

[George Elliott]

Hi Paul, needless to say I would'nt fit it again, but why did I fit it? Its because I was fed up with poor elec performance despite new Batteries, earth contact cleaning, New Porsche Starter motor, dim lights, slow elec windows even after new motors, blown taillight bulbs. All the time I was looking at a voltmeter on the dash saying 11.5v . The alternator tested as OK. ( Its not the adj regs fault its mine - I set it too high [&:] .)
Then I picked up on a Co in the US who claimed the Bosch units made low outputs as standard and it made perfect sense.
Now, I don't know what to do.
For 5 miles i enjoyed motronic like it was 15 generations newer. The car was so crisp. The windows were approx 50% quicker. You should have heard the starter motor..incredible - especially as when its turning the engine is not feeding a supply to the Battery.
I know what I want, - give me 12v on the engine management low volt circuits, and 15v everywhere else (especially the Coil).
Its a few hours work to refit my original regulator, so given that the adj version is capable of supplying the correct voltage I will likely leave it and keep an eye on the under-reading dash volt meter.
Your 3.2 development work has made fascinating reading, - the sky's the limit - you must have a cracking view from up there?? Well done and good luck with it.

Fen, I was with your opinion but got lucky.
Difficult choice on the mods, I'd observe the '44 is the most acceptable package out of the box or mildly modded. The '64 has a heavy flywheel and the std ECU needs it that way, - but then it has a good old chat with you when you steer it [] and you realise its irreplacable. GOOD to hear the '44 is'nt going away.

On another subject, I got a "page" earlier to allow me to add a picture of my car but its gone, anyone know how i do that pls?

George

 

[944turboS]

George,
re the picture posting either check the box just beneath where you type a reply & load from your PC or click the postage stamp type icon at the top of the text box to put in a link to a picture on the web.

 

[Fen]

If you go to the profile link under the club logo you can add an avatar and also a pic to your profile.

 

[944Turbo]

Hasn't Rick got an iceshark adj. voltage reg? Anyway dont trust the in dash guage.

Fen do the 944 - you dont want to end up with 2 broken Porsches [] You could take the flat 6 option and have more parts commonality []
Tony

 

[Fen]

If I do the 964 it'll be a "simple" take one engine out and put another one in then make custom exhausts and wiring loom to run it from the Autronic.

The '44 may end up being done something similar just for the sake of getting it going.

 

[sawood12]

The Iceshark kit does have an umproved voltage regulator but it also has other components that obviously make the kit work. I believe the guy who put the kit together was an electrical engineer so knew what he was doing.

When the voltage regulator fails it tends to suddenly increase the output. This is what happened to mine - i'd be driving along then all of a sudden the in-dash volt meter would go off the scale, the lights would go really bright and other electrical things would go into hyperdrive. If you drive the car in this state for too long then damage to the battery can result. You should be getting about 14v across the battery terminals if your voltage regulator is working.