New owner, now 172 won't start once warm???

[doilum]

Hi all, been skulking for around 10 days since I picked up my 52 plate 172. Been really happy with it so far, little pocket rocket!

This afternoon however it's decided to not start! Was fine when I started from cold ,and nipped to the shop, fine from the shop but after I'd parked at my next location (longer journey) and car was warmed up it just would not start. Engine was cranking but not firing up. Left it for 20 minutes or so and it fired up and ran fine.

Began to limp home and as I was driving it just cut out and stalled. At that time I was travelling along normally at around 30mph. Pulled in to the side of the road and again it was just turning over but not firing. Called the AA.

when they arrived 40 minutes later it started first turn of the key. Drove home no problem, power as usual, no funny noises etc, but once I switched the engine off it wouldn't start again, same as before just turning over but not firing.

I suspect some sort of sensor or electrical fault due to it starting cold but not warm but not sure what. Any one any ideas? I would appreciate any help!!!!!

 

[MicKPM]

Faulty crank position sensor... Classic symptoms

Mick

 

[doilum]

Thanks very much. Was thinking cam or crank. Easy fix or garage job?

 

[MicKPM]

Easy DIY but I'd consider fitting the updated blue sensor and fitting the new loom section. It's pricey but will stop it from happening again.

 

[doilum]

Cheers mick. Do you know of any 'how to' instructions anywhere? Bit of a novice engine for me having come from 6 pot BMW's!!!!

 

[MicKPM]

They're easy... Just two 10mm bolts on the gearbox and a single multi plug chap.

Mick

 

[Adam G]

Then fire over some beer money to Mick for his advice.:approve:

 

[doilum]

Top banana Mick, thanks very much! I shall have a delve on Monday providing I can get hold of one off the shelf from the stealer!

 

[doilum]

Replaced the part today, along with the updated wiring loom, and it seems to be sorted. Starts fine cold or warm now. The old part had a blue plug too but it wasn't marked as Renault so I imagine it was an eBay special!

Fingers crossed now!

 

[JoshOm3]

I had exact problems on my 19. As mick said, classic problems.

 

[gothy]

Would this sensor cause the same trouble when the engine is cold?
Mine is doing the opposite, all the above symptoms but when cold, yet fine when hot.

 

[MicKPM]

It's not "normal" for the CPS to fail at cold no. It is possible that the ECU isn't seeing engine rotation (due to a wiring fault maybe?) but to be sure you should get it plugged in and have the live data looks at.

Specifically you need to look at the engine speed line whilst cranking. If it stays at flatline then that's your issue but if it registers a speed then it's not and further investigation will be needed. It's also worth noting that a CPS fault will not alway declare a fault code! Sometimes if its unplugged it will but when they're just playing silly buggers they won't so don't pay for someone to plug in and read the codes off as it might be nothing more than a waste of cash.

Does the car make any coughing or spluttering noises wen you attempt to start it in the morning? If so its deffo not the CPS and more likely to be a CTS fault (again, live data will confirm or deny this).

Mick
Diamond Motors

 

[gothy]

Cts?
yes it does splutter when.cold.
my mechanic has replaced the plugs and the temp sensor to correct it, and now I've got a misfire too. But the real test shall come tomorrow morning, to see if it has cured it.

 

[daveypower]

great thread, some great advice.

 

[MicKPM]

Cts?
yes it does splutter when.cold.
my mechanic has replaced the plugs and the temp sensor to correct it

That's not CPS then and more likely to be CTS which if you've had changed should have sorted you out... Let us know.

Mick
Diamond Motors

 

[gothy]

Ive still got stalling, non starting, also a terrible misfire when cold.
I rang my mechanic who replaced the CTS, cleaned the TB, put new HT leads and plugs in.
Im thinking the crank sensor and a new coil...
OR should I try something else.

Also yesterday after it kept non starting then stalling, the car revved itself to 3000 rpm by itself, it slowed to 2500 but kept there.
So i turned her back off, and it hasnt done that since.

Im getting really annoyed with it now, Any ideas before I get a corsa VXR?

 

[MicKPM]

Take it somewhere that knows what they're doing... Guessing will get expensive and is unlikely to fix it.

Mick

 

[the_jons]

My 172 cup has a problem where it starts fine from stone cold, but won't crank if it's warm? I get a click from the solenoid but no cranking... I guess it's something up with the starter as it will bump start, but it's a pain to get to... A new one is £140 from Euro car parts, so I don't want to buy a replacement unless I have to, plus with it being fairly inaccessible I don't want to have to take it off to find out it's fine... Is there anything else I should check before getting it out? And what's the easiest way to get it out?
exhaust manifold off and out the top,
driveshaft out and out the bottom,
or a third way from the wheelarch out the side?

 

[chris blue]

looks my crankshaft centre needs replacing, doesnt always start when hot, just keep turning over

Was fine before i emptied all coolant and flushed out, then replaced coolant. (3 weeks ago tho) Vented at the bleed screw ok, but could the starting problem be thermostat related, and do you have to drain whole system when replacing thermostat?