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996 c4s would not start after 30 mile blast ?

Budgiec4s

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Joined
10 Apr 2016
Messages
101
So had a great drive out this morning 35 cars all pork. Weather was horendous but still had a great turn out.
Car hasn't been out for a good month or so and started on the button so was chuffed
Drove 15 miles and met the group no problems at all got in and started fine again after a 15 min break
Drove another 20 miles and stopped for brekkie. During this drive my wipers slowed and also windows slowed too.
After a 20 min stop car would not start ignition lights and crank just no go
Another owner lent me some jump leads and it fired up no problem
On returning home I left the car in the garage for a good half hour and then turned it over expecting it to be dead but it turned over and fired lovely
Anyone got any ideas why it let me down? And why the slow wipers?
I have put it on the c-tek now as I always do
Possible electrical fault?
Bad feed somewhere?
Thanks in advance guys
 
A bit of a needle in a haystack i feel .. cranking but not starting would kinda lead towards a CPS but that doesnt tie in with the other faults and also jump starting wouln,t make any difference to the car .

I have one idea and its this ..

http://911uk.com/viewtopic.php?t=118716&highlight=power+dist

Basically to check you remove the neg lead .. push the battery over then pull back the power pin lead .. if its rusty then it will need replacing .. if not then its something totally diferent .

A fault code read out of All the systems would be usefull here as it should show a few codes relateing to apower supply issue .
 
Without being able to see it and trouble shoot, but going by what you say - somethings stand out -

When hot it had problems, when cold it was fine.
There was a charging problem when you were driving as the wipers were slow.
Can you clarify if the engine was cranking but just didn't fire, or did it crank slow, or did it not crank at all before you tried the jump leads? I can't tell from what you have written.

There is a single connection between the alternator and the starter motor and the battery. This lead corrodes and when hot, has a high resistance so power from the alternator doesn't get to the battery and power from the battery (if there is any left) doesn't get to he starter and can make it sluggish.

A tired starter motor would only affect starting and not the wiper speed. Did you check your voltemeter at all? It should be reading 14v even with wipers and lights on. This would highlight a charging system problem. Monitor it.

A dodger alternator regulator (£25) can be affected by heat and the charging voltage drops as the engine gets hot and heats up the alternator. Charging voltage will drop to (in my case) 13v which can starve the battery.

Also, a dodgey battery can cause the same problem.

Best thing to do is to trouble shoot it - either yourself or a competent auto electrician- one that knows how to use and has an oscilloscope and not just a multi meter. Don't throw money at replacing the obvious things as it can be a waste.
 
Thanks a lot for the replies
To answer your questions
So the car when I tried to start just had a really sluggish turnover and nothing

I will have a good look through that thread thanks

I will also run the car into work one day this week hopefully and put the piwis on it see if it flagged anything up
 
Quick update
Ran a PIWIS test nothing to report
Also car started no problems at all yesterday morning no sluggish turnover

Could it just be the battery?
Does not make sense as it let me down after over an hour of driving and a half hour stop.

It's in my garage now so will strip out battery and check that pin at some point this week
 
It could be, but it might not be...

Heat seems to be an issue and that can affect all that I mentioned before. You could buy a new battery and it could solve the problem completely or just mask it for a while because it is fresh and strong.

A good auto electrician can disagnose battery health. A good auto electrician can used an oscilliscope to map the current and voltage during the starting phase and this can show up excessive current draw. An oscilloscope current graph can also be used to show the current draw changing as the starter motor turns - each compression is a spike in current - and as it is plotted over time you can determine how fast or slow the starter is spinning. This will indicate it's health.

The charging system can also be checked.

It would be easy for anyone to choose the alternator/ starter cable as this is a regular fault - but it might be that, and a weak alternator and and oldish battery.

Better to troubleshoot effectively and spend money wisely... that's just my thoughts.
 
Budgiec4s said:
Quick update
Ran a PIWIS test nothing to report
Also car started no problems at all yesterday morning no sluggish turnover

Could it just be the battery?
Does not make sense as it let me down after over an hour of driving and a half hour stop.

It's in my garage now so will strip out battery and check that pin at some point this week

You should test before you strip anything out.... looking At a cable will not tell you anything.

Go for a 30 min drive and get the car up to temp. . Watch if the alternator charge voltage drops off to less than 14v. Make sure lights and rear demos tee are on. After 30 min, turn of car and try to start it. If it is sluggish, the problem is probably heat related (but we think that already) and if the voltage had dropped off it is most likely charging system. But again, you need to test.
 
Budgiec4s said:
Quick update
Ran a PIWIS test nothing to report
Also car started no problems at all yesterday morning no sluggish turnover

Could it just be the battery?
Does not make sense as it let me down after over an hour of driving and a half hour stop.

It's in my garage now so will strip out battery and check that pin at some point this week

I made a mistake im afraid , i thought i was in the 997 forum when answering this post so you need to ignore what i wrote .. its only applicable to a 997 not a 996 :oops:
 

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