Porsche 911 UK Enthusiasts Online Community Discussion Forum GB

Welcome to the @Porsche911UK website. Register a free account today to become a member! Sign up is quick and easy, then you can view, participate in topics and posts across the site that covers all things Porsche.

Already registered and looking to recovery your account, select 'login in' and then the 'forget your password' option.

Not starting when hot.

MMT

Monza
Joined
18 May 2011
Messages
166
1999 C4 3.4
A couple of times recently I've driven for about 30 minutes, stopped for about 30 minutes and when I've gone back it won't start. I fitted a new battery about 3 months ago, so it turns over really well and generally starts straight away. I've tried opening the doors and locking/unlocking to see if it's an immobiliser issue, but that doesn't seem to make any difference. Last time I was at home so left it about an hour and it started straight away. Today, after some messing about it suddenly started after about 10 seconds turning over.
Any ideas guys please.
 
Is it cranking quickly but not starting, or not cranking? If not cranking, are the lights staying on on the dashboard?

MC
 
A lot of the time this is down to the battery, starter or earth cables. They are fine when cold but once warm expand and cause continuity issues.

Cleaning up of all the cables, battery, engine to chassis and around the starter motor where they connect is a no cost fix... if this is the issue?
 
Yes it's turning the engine, just doesn't make any attempt to fire up. Leave it half an hour more and it fires up first time.
I had an Impreza that wouldn't start when hot and on them it's a common a common fault with the crank position sensor. Is that possible on these.
 
I have had this problem. It is the crank position sensor breaking down. When it is failing it works fine when cold, but when hot,it creates a lot of 'noise' meaning the crank position can't be heard. Position sensor failure has been discussed a lot on here.
 
Had this problem and was told it was a corroded Alternator / Starter cable.

The resistant was changing when HOT was what I was told
 
Thanks guys.
The symptoms are exactly the same as my Impreza was.
👍🏼😎🍻
 
infrasilver said:
Yes, could easily be the CPS too, I have had issues with mine previously. It should throw a code for the CPS.

In my case, no code was thrown up! I checked out all the other obvious culprits like Steve997's suggestion of corroded cables to no avail. The CPS Bosch part wasn't expensive, so was worth a punt!
 
For some strange reason you dont tend to get a fault code for this .

My best guess is there is a signal but its too weak for the car to understand it or that the spin over is too brief for a code to be generated .

Symptoms like this are classic CPS failure though .

Starter cable faults tend to give low battery charge or slow spin over of the engine when hot .
 
I've had the car about 3 years. For the first 2.5 years it was really slow when turning over. I got the garage to check out all the cables as suggested on here and they couldn't find anything. They even ran some jumper leads from some points to see if it improved. The battery was supposed to have checked out good as well. About 6 weeks ago it wouldn't start and flattened the battery quite quickly so I just went and bought a new battery and since then it's turned over really fast. So I don't think there are any earth or connection issues.
Does this look like the part.
https://www.eurocarparts.com/ecp/c/...4394fc74c14d76499abf50c897efc123e64e0b&000440
 

Attachments

  • a612c6f2_552d_4caa_9398_f59eec77b8c1_654.png
    a612c6f2_552d_4caa_9398_f59eec77b8c1_654.png
    316.6 KB · Views: 3,303
Hi MMT,

Looks like the part I bought, though at more than £100 it is about twice the price of what I paid about 3 years ago!! Inflation I suppose.
 

New Threads

Forum statistics

Threads
124,532
Messages
1,441,223
Members
48,943
Latest member
stevemias
Back
Top