intermittiant starting issues

[beechey]

just recently say 5 times this month car just wont start leave it a hour its fine
and when running its fine
its doing all the correct noise etc trying to turn over ?
its just so random cars been isses free for 5-6 years

 

[sockpuppet]

Is it a hot start problem, where car turns over, fires up and then stalls after a second?

 

[Alexis27]

Battery and/or coilpacks would be my guess.

 

[mty12345]

I take it that it turns over on the starter motor, but just doesn't start?

If so and it only happens when it's hot, it could be a faulty coolant temp sensor.... If that fails then the ECU adds enough fuel to start the engine from cold. If it's a really hot day and the engine is still hot as well, then that can make the mixture so rich that it just won't start.

Note that the temp sensor has 2 parts, one part that supplies the dash gauge, one part that supplies the ECU, so the dash gauge can be fine but the ECU may well be getting the wrong signal.

Easy was to tell is to look at the temp on VCDS, The Torque app, or any OBD2 reader that does live data.

 

[beechey]

well it has not done it since,
when it starts its fine,
car has a recent new battery
I haven't got any of the vcds, the torque app, obd2
which do you recommend as I need to invest in one

 

[mty12345]

Vcds is by far the best, but your looking at about £225. That can read fault codes for every module in the car, including air-con, central locking etc etc etc. https://www.gendan.co.uk/product_VCV23.html

If you have an android phone, the the torque app plus a ELM327 adaptor from ebay will allow you to read fault codes from the engine and monitor a certain amount of basic live data such a temp and boost etc etc. The app and the adaptor cost less than £20 all in.

Ebay also has many cheap OBD2 readers that will allow reading of engine fault codes too. Again they are from about £20 upwards.

 

[beechey]

thanks ill purchase one today, hopefully fault was a sticky relay or summit