25 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHIntermittent Non-Start
Leading reported evidence
Check battery earth strap
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
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0
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1
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Leading evidence: 'Check battery earth strap' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check battery earth strap' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion
I'd be checking voltage drop at the starter trying to crank from cold and also the starter signal wire if you are getting no click.
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Suggestion
Check battery terminals, starter motor connections and earth straps are all tight and clean of corrosion.
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Suggestion
Does yours have the correct cranking Amps (74 to 95Ah) as it sounds like it is struggling without you using a booster.
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So.... got rid of my C4 Cab and now got an early 996.1 manual C2 Coupe. Love it. But...
It has an intermittent starting issue where sometimes it won't start. Lights on dash, hvac and radio come on but no crank. The frustrating thing is there doesn't seem to be any rhyme or reason as to why. The only pattern seems to be the longer it is left without starting, the more likely it is to not start (hot starts aren't an issue). Sometimes it starts first time, sometimes takes two or three goes, sometimes doesn't want to play ball at all.
Luckily there is a good stack of invoices so I can see any work that has been done that might be relevant.
Work by previous owners:
New starter
New ECU (for non-start issue)
Work done by me:
New engine earth strap
Checked battery earth strap
Changed ignition switch
"Black box" under passenger seat seems fine
Minor electrical gremlins:
Xenon retrofit kit on headlights - NS light flickers and when it does get some audible crackling feedback through speakers (I'm going to put it back to standard)
Stereo sometimes goes unresponsive
Remote locking works fine
Unsure if it really does help but jumping with a booster when it's not starting seems to increase chances of it starting (simply putting charger on overnight doesn't make any difference)
Battery health is at 92%
I love a challenge but after seemingly trying every other option I've found on t'internet, bit stumped.
Does the starter click or no noise at all?
I'd be checking voltage drop at the starter trying to crank from cold and also the starter signal wire if you are getting no click.
Good luck.
You seem to have done all the essential stuff and I would only try another new battery as a last resort. Does yours have the correct cranking Amps (74 to 95Ah) as it sounds like it is struggling without you using a booster. Maybe you need a higher CCA because of the retro fit xenons. Was it starting okay before the xenon fit??
Other than that one of the connectors to the starter motor must be rusty/greasy or poor (my guess)
Pip
Grief new ECU ! That can’t of been cheap ! Who ever did that must of exhausted all avenues surely ?!
Batteries can read good volts but collapse under cranking load, you can drop test them, not sure many people do it nowadays
If you’re at all unsure I’d want a brand new Battery on it.
As Hooner said if you bridge out the starter it’ll soon tell you if you’re chasing a Gremlin.
Does it have an alarm ? Immobiliser ?
Does it have a battery drain ? If it’s only doing it once it’s been sitting for a period ?
I've got one - no fault codes
I recently put a new battery in my 944 so might swap that and see. Took the 996 down to my local auto supplies store who health checked it for me at 92% which I would have thought would be ok?
Not sure about the xenons - I didn't fit them and keen to put them back to stock bulbs, even if they are rubbish (just need to work out how to do it)
This might be worth a shot too...
£650
Alarm works. As I understand it, there's a transponder for the immobiliser in the key that talks to the car. That could be on the blink. I only have one key so might need another one programming? Not sure there's drain. I didn't drive it for three weeks while I was away recently - that time it fired up first time when I got back....
Just the US ones I think - mine will start without clutch being depressed.
Only other thing I can think of is maybe water is getting in somewhere.....? Took about ten goes to get it started today and it rained last night but when I left it for three weeks it was inside....
I have a similar problem with my 997.2 C2S. SOMETIMES all the lights will come on but it will not turn over when the key is turned....... BUT if I get out, lock the car, unlock the car and get in again IT STARTS !???
So I am thinking it is something related to the immobiliser time-out or some such like. Any thoughts?
If it always starts when it's hot start? then heat expands metal and thus connection/switch is better somewhere so yes starter relay worth switching or looking at the starter wires.
Crank Sensor would likely show no movement on tacho, but you say it cranks just doesn't fire? Tachno move? If there is no history of a crank sensor then being a .1 and if it's original then pretty old.
Yeah, not that then.
iCarsoft. Was fine when I had my C4 Cab - helped me diagnose and fix all my faults (and there were lots)
Interesting - yes, this could be something to look into more....
No crank at all so think that rules out position sensor but will try the relay, thanks
What is the Amperage of your current battery though and its CCA?
Poor starting after being out in the rain for a while could point to moisture on a connector somewhere.
Pip
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